JP2021189036A - Electron beam irradiation apparatus and method for manufacturing electron beam irradiation apparatus - Google Patents

Abstract

To provide an electron beam irradiation apparatus capable of achieving the longer life of a window foil member, and a method for manufacturing the same.SOLUTION: An electron beam irradiation apparatus 1 comprises: a filament unit 2 for generating an electron beam, a vacuum vessel 3 having an opening 3a for passing the electron beam generated from the filament unit 2; a window member 9 arranged in the opening 3a and including window foil 9a transmitting the electron beam EB passing through the opening 3a; and a control part 50 for controlling the filament unit 2. The window foil 9a is a foil member including titanium as a main component; the thickness of the window foil 9a is 2×10-3 mm or more and 1x10-2 mm or less; and the control part 50 sets the drive voltage of the filament unit 2 so that the tube voltage of the filament unit 2 is 40 kV or more and 150 kV or less and sets the drive current of the filament unit 2 so that a current area density in the window foil 9a is 5.3 mA/mm2 or less.SELECTED DRAWING: Figure 3

Description

The present invention relates to an electron beam irradiator and a method for manufacturing an electron beam irradiator.

As a conventional electron beam irradiation device, an electron beam generating portion for generating an electron beam, a housing provided with an opening for passing an electron beam generated from the electron beam generating portion, and an opening arranged in the opening are provided. It is known that an electron beam irradiation window portion having a window foil member that allows the passed electron beam to pass through is provided (see Patent Document 1).

In the electron beam irradiation device described in Patent Document 1, a current of several amperes is applied to the filament from the power supply device, and a power supply voltage of several tens of kV to several hundred kV is applied to the filament from another power supply device, and electrons are emitted from the filament. The electrons emitted from the filament are accelerated by the grid portion to become electron beams and reach the window unit. The electron beam passes through the window material of the window unit having a long or rectangular shape, for example, and is emitted to the outside of the electron beam generator in a line shape or a spot shape, respectively.

Japanese Unexamined Patent Publication No. 2007-240454

In the electron beam irradiation device as described above, improvement in operation stability is required so that the electron beam can be stably emitted for a longer period of time. For that purpose, for example, it is conceivable to set the drive current of the electron beam generating portion so that the temperature of the window foil member becomes appropriate to extend the life of the window foil member.

Therefore, an object of the present invention is to provide an electron beam irradiating device and a method for manufacturing an electron beam irradiating device capable of extending the life of the window foil member.

The electron beam irradiating device according to the present invention is arranged in an electron beam generating portion for generating an electron beam, a housing portion provided with an opening for passing an electron beam generated from the electron beam generating portion, and an opening. The window foil member includes an electron beam irradiation window portion having a window foil member that allows an electron beam that has passed through the opening to pass through, and a control unit that controls an electron beam generating portion. The window foil member is a foil member containing titanium as a main component. Yes, the thickness of the window foil member is 2 × 10 ^-3 mm or more and 1 × 10 ^-2 mm or less, and the control unit is charged with electrons so that the tube voltage of the electron beam generating unit is 40 kV or more and 150 kV or less. The drive voltage of the wire generator is set, and the drive current of the electron beam generator is set so that the current surface density of the window foil member is 5.3 mA / mm ^{2 or less.}

In this electron beam irradiation device, the drive voltage and drive current of the electron beam generation unit by the control unit are set so that the ^{current surface density in the window foil member is suppressed to 5.3 mA / mm 2 or less.} As a result, for example, the temperature rise of the window foil member is suppressed within an appropriate range as compared with the case where the drive voltage and the drive current are set without such limitation of the current surface density. Therefore, the life of the window foil member can be extended.

The current surface density may be a value obtained by dividing the tube current of the electron beam generating portion by the area of the incident region of the electron beam in the window foil member. In this case, since the current surface density using the area value of the incident region of the electron beam in the window foil member is used, the incident of the electron beam is compared with the case of using the current density using the value of the distance in one direction in the incident region. The life of the window foil member can be effectively extended for the entire area.

The control unit may control the drive current so that the current surface density decreases as the drive voltage decreases for the window foil member having one type of thickness. In this case, when the drive voltage becomes small, it becomes difficult for the electron beam to pass through the electron beam irradiation window portion, so that the current surface density tends to increase. Therefore, by controlling the drive current so that the current surface density becomes small, it is possible to suppress the temperature rise of the window foil member within an appropriate range.

The control unit calculates and calculates the approximate value of the critical current surface density approximated by a quadratic function with the drive voltage of the electron beam generator as a variable, based on the drive voltage of the electron beam generator and the thickness of the window foil member. The drive current of the electron beam generator may be set so as to be equal to or less than the approximate value of the critical current surface density. In this case, even if the drive voltage of the electron beam generator changes with the thickness of the window foil member determined, the drive current of the electron beam generator is calculated using the approximate value of the critical current surface density approximated by the quadratic function. It can be set easily.

The control unit calculated and calculated the approximate value of the critical current surface density approximated by a linear function with the thickness of the window foil member as a variable, based on the drive voltage of the electron beam generating unit and the thickness of the window foil member. The drive current of the electron beam generator may be set so as to be equal to or less than the approximate value of the critical current surface density. In this case, even if the thickness of the window foil member changes at the drive voltage of the electron beam generator, the drive current of the electron beam generator is calculated using the approximate value of the critical current surface density approximated by the linear function. It can be set easily.

Specifically, the thickness of the window foil member is 3 × 10 ^-3 mm or more and 5 × 10 ^-3 mm or less, and the control unit is the tube of the electron beam generation unit. Even if the drive voltage of the electron beam generator is set so that the voltage is 130 kV or less and the drive current of the electron beam generator is set so that the current surface density in the window foil member is 5.3 mA / mm ² or less. good.

Specifically, the thickness of the window foil member is 4 × 10 ^-3 mm or more and 5 × 10 ^-3 mm or less, and the control unit is the tube of the electron beam generation unit. Even if the drive voltage of the electron beam generator is set so that the voltage is 130 kV or less and the drive current of the electron beam generator is set so that the current surface density in the window foil member is 4.7 mA / mm ² or less. good.

Specifically, the thickness of the window foil member is 5 × 10 ^-3 mm, and the control unit is set so that the tube voltage of the electron beam generating unit is 130 kV or less. The drive voltage of the electron beam generator may be set, and the drive current of the electron beam generator may be set so that the current surface density in the window foil member is 4.0 mA / mm ^{2 or less.}

The method for manufacturing an electron beam irradiating device according to the present invention includes an electron beam generating portion for generating an electron beam, a housing portion provided with an opening for passing an electron beam generated from the electron beam generating portion, and an opening. It is a manufacturing method of an electron beam irradiation apparatus including an electron beam irradiation window portion which is arranged and has a window foil member for transmitting an electron beam passing through an opening, and a control unit for controlling an electron beam generating portion. In the window foil member, based on the first step of setting the range of the drive voltage of the electron beam generating portion by the unit, the second step of specifying the area of the incident region of the electron beam in the window foil member, and the area of the incident region. A third step of setting the range of the drive current of the electron beam generating unit so that the current surface density becomes equal to or less than a predetermined limit current surface density is provided.

In this method of manufacturing an electron beam irradiation device, the drive voltage and drive current of the electron beam generation unit by the control unit are set so that the current surface density in the window foil member is suppressed to be equal to or lower than the limit current surface density. As a result, for example, the temperature rise of the window foil member is suppressed within an appropriate range as compared with the case where the drive voltage and the drive current are set without such limitation of the current surface density. Therefore, the life of the window foil member can be extended.

The second step is a step of arranging a fluorescent member in place of the window foil member, a step of acquiring the area of the light emitting region emitted by the incident of the electron beam in the fluorescent member as the area of the incident region, and the acquisition of the area of the light emitting region. It may also include a step of later removing the fluorescent member and arranging the window foil member. In this case, since the current surface density using the area value of the incident region of the electron beam in the window foil member is used, the incident of the electron beam is compared with the case of using the current density using the value of the distance in one direction in the incident region. The life of the window foil member can be effectively extended for the entire area. In addition, the incident region can be easily specified by using the light emitting region of the fluorescent member.

The method for manufacturing the electron beam irradiation device ^{includes a fourth step of preparing a window foil member having a thickness of 2 × 10 -3} mm or more and 1 × 10 ⁻² mm or less, and in the third step, one type is provided. The upper limit of the drive current range may be set smaller as the upper limit of the drive voltage range set in the first step becomes smaller for the window foil member having a thickness. In this case, when the drive voltage becomes small, it becomes difficult for the electron beam to pass through the electron beam irradiation window portion, so that the current surface density tends to increase. Therefore, by setting the upper limit of the drive current range to a small value, it is possible to suppress an increase in the current surface density and suppress a temperature rise of the window foil member within an appropriate range.

In the third step, based on the drive voltage of the electron beam generator and the thickness of the window foil member, the approximate value of the critical current surface density approximated by the quadratic function with the drive voltage of the electron beam generator as a variable is calculated. The drive current of the electron beam generator may be set so as to be equal to or less than the calculated limit current surface density approximation value. In this case, even if the drive voltage of the electron beam generator changes with the thickness of the window foil member determined, the drive current of the electron beam generator is calculated using the approximate value of the critical current surface density approximated by the quadratic function. It can be set easily.

In the third step, based on the drive voltage of the electron beam generator and the thickness of the window foil member, the approximate value of the critical current surface density approximated by the linear function with the thickness of the window foil member as a variable is calculated and calculated. The drive current of the electron beam generating unit may be set so as to be equal to or less than the approximate value of the critical current surface density. In this case, even if the thickness of the window foil member changes at the drive voltage of the electron beam generator, the drive current of the electron beam generator is calculated using the approximate value of the critical current surface density approximated by the linear function. It can be set easily.

As a configuration that preferably exerts the above-mentioned action and effect, specifically, in the method for manufacturing the above-mentioned electron beam irradiation device, a window foil member having ^{a thickness of 3 × 10 -3} mm or more and 5 × 10 ^{-3 mm or less is prepared.} A fourth step is provided. In the first step, the range of the drive voltage of the electron beam generator by the control unit is set so that the tube voltage of the electron beam generator is 130 kV or less, and in the third step, the window foil member is used. The range of the drive current may be set so that the current surface density is 5.3 mA / mm ^{2 or less.}

As a configuration that preferably exerts the above-mentioned action and effect, specifically, in the method for manufacturing the above-mentioned electron beam irradiation device, a window foil member having ^{a thickness of 4 × 10 -3} mm or more and 5 × 10 ^{-3 mm or less is prepared.} A fourth step is provided. In the first step, the range of the drive voltage of the electron beam generator by the control unit is set so that the tube voltage of the electron beam generator is 130 kV or less, and in the third step, the window foil member is used. The drive current range may be set so that the current surface density is 4.7 mA / mm ^{2 or less.}

Specifically, the method for manufacturing the electron beam irradiation device includes a fourth step of preparing a window foil member having ^{a thickness of 5 × 10 -3} mm, and the first step, as a configuration that preferably exerts the above-mentioned action and effect. In the step, the range of the drive voltage of the electron beam generator by the control unit is set so that the tube voltage of the electron beam generator is 130 kV or less, and in the third step, the current surface density in the window foil member is 4.0 mA /. The range of the drive current may be set so as to be mm ^{2 or less.}

According to the present invention, the life of the window foil member can be extended.

FIG. 1 is a perspective view of the electron beam irradiation device according to the first embodiment. FIG. 2 is a partial cross-sectional view showing the internal structure of the electron beam irradiation device of FIG. FIG. 3 is a cross-sectional view taken along the line III-III of FIG. FIG. 4 is an exploded perspective view of the window member. FIG. 5 is an exploded cross-sectional view of the window member and the cooling unit along the YZ plane. FIG. 6 is a perspective view of the cooling unit of FIG. FIG. 7 is an exploded cross-sectional view of the window member and the cooling unit along the ZX plane. FIG. 8 is a diagram showing actual measured values of the current surface density of the electron beam irradiator of FIG. 1. FIG. 9 is a diagram showing simulated values of the current surface density of the electron beam irradiator of FIG. 1. FIG. 10 is a diagram showing the relationship between the critical current surface density of FIGS. 8 and 9 and the tube voltage. FIG. 11 is a diagram showing the relationship between the critical current surface density of FIGS. 8 and 9 and the thickness of the window foil member. FIG. 12 is a flowchart showing a method of manufacturing an electron beam irradiation device. FIG. 13 is a flowchart showing the area specifying process of FIG. FIG. 14 is a side sectional view of the electron beam irradiation device according to the second embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each figure, the same or corresponding elements are designated by the same reference numerals, and duplicate description will be omitted.

[First Embodiment]
The electron beam irradiation device 1 shown in FIG. 1 is used to cure, sterilize, or modify the surface of the ink of the irradiation target by irradiating the irradiation target with the electron beam EB. Hereinafter, the electron beam emitting side (window member 9 side), which is the side on which the electron beam EB is irradiated by the electron beam irradiating device 1, will be described as the “front side”.

As shown in FIGS. 1 to 3, the electron beam irradiating device 1 includes a filament unit 2 (electron beam generating portion), a vacuum container (housing portion) 3, a cathode holding member 4, a cathode holding member 5, and a surrounding electrode 6. , A high voltage introduction insulating member 7, an insulating support member 8, and a window member (electron beam irradiation window portion) 9 are provided. The filament unit 2 is an electron beam generating unit that generates an electron beam EB. Further, the filament unit 2 is a long unit.

The vacuum container 3 is made of a conductive material such as metal. The vacuum container 3 has a substantially cylindrical shape. The vacuum vessel 3 forms a substantially columnar vacuum space R inside. The filament unit 2 is arranged inside the vacuum vessel 3 along the axial direction of the substantially cylindrical vacuum space R. An opening 3a connecting the vacuum space R and the external space is provided at a position on the front side of the filament unit 2 in the vacuum container 3. The opening 3a is an opening through which the electron beam EB generated from the filament unit 2 passes. The window member 9 is fixed to the opening 3a so as to cover the entire opening 3a and be vacuum-sealed. The details of the window member 9 will be described later.

An exhaust port 3b for exhausting the air in the vacuum vessel 3 is provided at a position on the rear side of the filament unit 2 in the vacuum vessel 3. A vacuum pump (not shown) is connected to the exhaust port 3b, and the air in the vacuum container 3 is discharged by the vacuum pump. As a result, the inside of the vacuum container 3 becomes a vacuum space R. The openings 3c and 3d (see FIG. 2) at both ends of the vacuum vessel 3 having a substantially cylindrical shape are closed by the flange portion 7a and the lid portion 3e of the high voltage introduction insulating member 7, respectively.

The pair of cathode holding members 4 and 5 that serve as the cathode potential are arranged in the vacuum vessel 3, respectively. A part of the filament unit 2 is formed between the cathode holding member 4 and the cathode holding member 5, and a surrounding electrode 6 which is a cathode potential is provided. The surrounding electrode 6 is a conductive and long member having a substantially C-shaped cross section. The surrounding electrode 6 is arranged so that the opening having a substantially C-shaped cross section faces the front side (window member 9 side). The surrounding electrode 6 houses the filament 10 (see FIG. 3) in the inner portion. For example, the filament unit 2 is inserted into the surrounding electrode 6 through the insertion holes provided in the cathode holding member 5 and the insulating support member 8 in a state where the lid portion 3e of the vacuum container 3 is removed. It is held by the surrounding electrode 6.

The high voltage introduction insulating member 7 is provided at the end of the vacuum vessel 3 on the opening 3c side. One end of the high voltage introduction insulating member 7 projects to the outside of the vacuum vessel 3 through the opening 3c. The high voltage introduction insulating member 7 has a flange portion 7a overhanging to the outside, and seals the opening portion 3c of the vacuum vessel 3. The high voltage introduction insulating member 7 is formed of an insulating material (for example, an insulating resin such as an epoxy resin, ceramic, or the like). The cathode holding member 4 holds the other end of the high voltage introduction insulating member 7 in a state of being electrically insulated from the vacuum vessel 3 which is the ground potential.

Further, the high voltage introduction insulating member 7 is a high withstand voltage type connector for receiving a high voltage supply from an external power supply device of the electron beam irradiation device 1. A high voltage supply plug is inserted into the high voltage introduction insulating member 7 from a power supply device (not shown). Inside the high voltage introduction insulating member 7, an internal wiring for supplying a high voltage supplied from the outside to the filament unit 2 is provided. This internal wiring is covered with an insulating material constituting the high voltage introduction insulating member 7, and insulation with the vacuum container 3 is ensured.

The insulating support member 8 is provided at the end portion of the vacuum vessel 3 on the opening 3d side (the end portion on the lid portion 3e side). The insulating support member 8 is formed of an insulating material (for example, an insulating resin such as an epoxy resin, ceramic, or the like). The cathode holding member 5 holds the insulating support member 8 in a state of being electrically insulated from the vacuum container 3.

As shown in FIG. 3, the filament unit 2 includes a surrounding electrode 6, a filament 10, and a grid electrode 12.

The filament 10 is an electron emitting unit that emits an electron that becomes an electron beam EB when heated by energization. The filament 10 is a linear member and extends along a desired axis extending along the long axis direction of the vacuum vessel 3 (the axis direction of the vacuum space VR). The filament 10 is formed of a refractory metal material, for example, a material containing tungsten as a main component.

The grid electrode 12 is arranged on the front side of the filament 10 so as to cover the opening of the surrounding electrode 6. A plurality of holes are formed in the grid electrode 12.

The filament 10 emits electrons when a high negative voltage such as minus several tens of kV to minus several 100 kV is applied in a state of being heated by energization. A predetermined voltage is applied to the grid electrode 12. For example, a voltage on the positive side of about 100V to 150V may be applied to the grid electrode 12 with respect to the negative voltage applied to the filament 10. The grid electrode 12 forms an electric field for drawing out electrons and suppressing diffusion. As a result, the electrons emitted from the filament 10 are emitted forward as electron beams EB from the holes provided in the grid electrode 12.

Next, the details of the window member 9 will be described. FIG. 4 is an exploded perspective view of the window member. As shown in FIG. 4, the window member 9 has a window foil (window foil member) 9a, a support 9b, a window flange 9c, a sealing material 9d, and a holding flange 9e.

In the window member 9, the window flange 9c is attached so as to cover the opening 3a of the vacuum container 3. A window foil 9a, a support 9b, and a sealing material 9d are arranged in the inner region of the window member 9 (that is, so as to fit inside the window member 9 when the window member 9 is viewed from the front side). The window flange 9c and the holding flange 9e are made of, for example, oxygen-free copper (material containing copper), and have a rectangular frame-shaped outer shape with the axial direction of the vacuum space R as the longitudinal direction.

A groove extending so as to surround the support 9b is provided on the outside of the region where the support 9b is arranged on the front surface of the window flange 9c, and a sealing member which is an airtight sealing member is provided in the groove. The material 9d is arranged. As the sealing material 9d, for example, a resin O-ring can be used.

The window foil 9a is a metal film formed in the form of a thin film. The window foil 9a allows the electron beam EB that has passed through the opening 3a to pass through. As the material of the window foil 9a, a material having excellent transparency of the electron beam EB (for example, beryllium, titanium, aluminum, etc.) is used. The window foil 9a here is a foil member containing titanium as a main component, and is, for example, a pure titanium foil. The window foil 9a is arranged on the mesh portion so as to be in contact with the mesh portion of the support 9b. The window foil 9a extends in the axial direction (predetermined direction) of the vacuum space R as the longitudinal direction. The thickness of the window foil 9a is 2 × 10 ^-3 mm or more and 1 × 10 ^-2 mm or less. The thickness of the window foil 9a may be, for example, 3 × 10 ^-3 mm, 4 × 10 ^-3 mm, or 5 × 10 ^-3 mm. The thickness of the window foil 9a does not necessarily have to be an actually measured value, and may be a nominal value as a specification of the window foil 9a.

The support 9b is a flat plate-shaped member arranged on the vacuum space R side of the window foil 9a and supporting the window foil 9a. The support 9b is a mesh-shaped member, and extends in the axial direction (predetermined direction) of the vacuum space R as the longitudinal direction. As the material of the support 9b, for example, copper, titanium, or aluminum can be used. The support 9b has a mesh portion that covers the opening 3a. The mesh portion is composed of, for example, a plurality of through holes. The through hole is a hole for passing the electron beam EB from the inside to the outside of the vacuum container 3.

In the window member 9 having the above configuration, the window flange 9a, the support 9b, and the sealing material 9d are pressed against the window flange 9c, and are airtightly fixed to the window flange 9c by, for example, a plurality of bolts. ing.

During the operation of the electron beam irradiating device 1, the electron beam transmitting region 9f in the window foil 9a becomes particularly hot. The electron beam transmission region 9f is an incident region of the electron beam EB in the window foil 9a. When the thickness of the window foil 9a is reduced, the heat of the window foil 9a is less likely to be transmitted to the window flange 9c and the holding flange 9e side, so that the electron beam transmission region 9f of the window foil 9a tends to become high in temperature. The electron beam irradiation device 1 here includes a cooling unit 100 for cooling the window foil 9a.

FIG. 5 is an exploded cross-sectional view of the window member and the cooling unit along the YZ plane. FIG. 6 is a perspective view of the cooling unit of FIG. FIG. 7 is an exploded cross-sectional view of the window member and the cooling unit along the ZX plane. As shown in FIGS. 5 to 7, a cooling unit 100 is provided on the electron beam transmitting side of the window member 9. The cooling unit 100 cools the window foil 9a by spraying a gas (for example, an inert gas such as nitrogen) on the window foil 9a. The cooling unit 100 includes a tubular member 101 through which gas flows, and a fixed frame body 110 to which the tubular member 101 is fixed.

The fixed frame 110 has a substantially rectangular frame-like outer shape with the Y-axis direction as the longitudinal direction by a pair of long side portions 111 extending in the Y-axis direction and a pair of short side portions 112 extending in the X-axis direction. Is doing. The fixed frame body 110 can be covered so as to accommodate the window member 9 inside the fixed frame body 110. The fixed frame body 110 is fixed to the electron beam irradiation device 1 in a state of covering the window member 9.

The tubular member 101 is a member made of a metal material having a hollow long cylindrical shape, and gas can flow through an internal space as a flow path. The tubular member 101 is arranged along the longitudinal direction of the fixed frame 110. An air supply nozzle 103 provided with an air supply port 103a is connected to one side of the tubular member 101, and the other end side of the tubular member 101 is sealed by a sealing material 104.

The side wall 101c of the tubular member 101 is provided with a plurality of small-diameter through holes 101d having a circular cross section penetrating the inside and the outside of the tubular member 101 at a predetermined pitch. The plurality of through holes 101d are arranged linearly in the longitudinal direction with respect to the side wall 101c. The plurality of through holes 101d are located so as to face the window foil 9a. Therefore, the gas supplied from the air supply port 103a is ejected from the through hole 101d. The window foil 9a is cooled by blowing gas as cooling air from the cooling unit 100. As the cooling unit for cooling the window foil 9a, for example, a structure for blowing gas may be provided on the flange 9e, a water cooling structure may be provided on the window flange 9c, or they may be used in combination.

Even if the cooling unit 100 as described above is provided, for example, if the drive current of the filament unit 2 becomes excessive, the temperature of the window foil 9a may exceed the allowable temperature, and the window foil 9a may be damaged by heat. There is. Therefore, the electron beam irradiation device 1 includes a control unit 50 that controls the filament unit 2 so that the temperature rise of the window foil 9a is within an appropriate range.

The control unit 50 is configured as a computer device including a processor, a memory, a storage, and the like. In the control unit 50, the function of the control unit 50 is realized by the processor executing predetermined software (program) read into the memory or the like and controlling the reading and writing of data in the memory and the storage. The control unit 50 may be configured as hardware using an electronic circuit or the like.

The control unit 50 sets the drive voltage of the filament unit 2 so that the tube voltage of the filament unit 2 is 40 kV or more and 150 kV or less. The tube voltage of the filament unit 2 is an acceleration voltage of the electron beam EB corresponding to the difference between the voltage of the window member 9 and the voltage of the filament 10. The drive voltage of the filament unit 2 means a voltage applied to the filament unit 2.

The control unit 50 has a filament unit 2 having a tube voltage range of 40 kV to 100 kV, 40 kV to 110 kV, 40 kV to 120 kV, 40 kV to 130 kV, 40 kV to 140 kV, and 40 kV to 150 kV. The drive voltage of the unit 2 may be set. The control unit 50 has a filament unit 2 having a tube voltage range of 50 kV to 100 kV, 50 kV to 110 kV, 50 kV to 120 kV, 50 kV to 130 kV, 50 kV to 140 kV, and 50 kV to 150 kV. The drive voltage of the unit 2 may be set. The control unit 50 may set the drive voltage of the filament unit 2 so that the lower limit of the tube voltage range of the filament unit 2 is any of 60 kV, 70 kV, 80 kV, 90 kV, and 100 kV.

The control unit 50 sets the drive current of the filament unit 2 so that the current surface density in the window foil 9a is equal to or less than a predetermined limit current surface density. The drive current of the filament unit 2 corresponds to the tube current of the filament unit 2 and corresponds to the current (beam current) of the electron beam EB from the filament 10 to the window member 9. The tube current of the filament unit 2 can be obtained by measuring the current of the electron beam EB from the filament 10 to the window member 9 by a known method.

The current surface density is a value obtained by dividing the tube current of the filament unit 2 by the area of the electron beam transmission region 9f (incident region of the electron beam EB) in the window foil 9a. The unit of the current surface density is, for example, (mA / mm ² ). The critical current surface density means a current surface density with a high probability that even if the window foil 9a is cooled by the cooling unit 100, the temperature of the window foil 9a exceeds the allowable temperature and the window foil 9a is damaged by heat.

The area of the electron beam transmission region 9f can be obtained in advance as follows, for example. First, in the window member 9, a fluorescent member is arranged in place of the window foil 9a. The fluorescent member is a member that emits fluorescence when an electron beam EB is incident, and has an outer shape similar to that of, for example, a window foil 9a. The thickness of the fluorescent member may be equal to or different from the thickness of the window foil 9a. Subsequently, the electron beam EB is incident on the fluorescent member in a state where the fluorescent member is arranged. As a result, the region where the electron beam EB is incident on the fluorescent member emits light. Subsequently, the area of the light emitting region that emits light due to the incident of the electron beam EB is acquired as the area of the electron beam transmission region 9f. The light emitting region has a shape corresponding to the configuration of the filament 10 and the grid electrode 12. In the electron beam irradiation device 1, the fluorescent member emits light with a light emission intensity in a rectangular range facing the filament 10 and the grid electrode 12, for example, corresponding to the extending range of the long filament 10 and the grid electrode 12. .. The area of the light emitting region can be the area of the region where the fluorescent member emits light with a light emitting intensity equal to or higher than a predetermined intensity. The area of the light emitting region may be acquired by, for example, a binarization method. In acquiring the area, the emission intensity may be substantially uniform, or the central portion may be stronger than the peripheral portion. After that, the fluorescent member is removed and the window foil 9a is placed.

The area of the electron beam transmission region 9f may be acquired by using an object that emits light due to the incident of the electron beam EB without removing the window foil 9a. For example, ceramics for electron beam measurement such as alumina, commercially available fluorescent powder, or glass can be used.

In calculating the critical current surface density, the temperature of the window foil 9a exceeds the allowable temperature when the window foil 9a is cooled by the cooling unit 100 as the tube current of the filament unit 2, and the window foil 9a is damaged by heat. The tube current of the filament unit 2 at that time can be used. When the window foil 9a is cooled by the cooling unit 100 by setting the drive current of the filament unit 2 so that the control unit 50 is equal to or less than the limit current surface density using such a limit current surface density. It is suppressed that the temperature of the window foil 9a exceeds the allowable temperature, and the possibility that the window foil 9a is damaged by heat is reduced.

FIG. 8 is a diagram showing actual measured values of the current surface density of the electron beam irradiator of FIG. 1. FIG. 8 shows the critical current surface density obtained by the experiment using the electron beam irradiation device 1 for each the thickness of the window foil 9a and the tube voltage of the filament unit 2.

As shown in FIG. 8, ^{when the window foil 9a having a thickness of 3 × 10 -3} mm was used, the critical current surface density at a tube voltage of 130 kV was 5.26 mA / mm ² . When the window foil 9a having a thickness of 3 × 10 ^-3 mm was used, the critical current surface density at a tube voltage of 90 kV was 2.38 mA / mm ² . When the window foil 9a having a thickness of 3 × 10 ^-3 mm was used, the critical current surface density at a tube voltage of 70 kV was 1.27 mA / mm ² . When the window foil 9a having a thickness of 3 × 10 ^-3 mm was used, the critical current surface density at a tube voltage of 50 kV was 0.51 mA / mm ² .

Further, when the window foil 9a having a thickness of 5 × 10 ^-3 mm was used, the critical current surface density at a tube voltage of 130 kV was 3.68 mA / mm ² . When the window foil 9a having a thickness of 5 × 10 ^-3 mm was used, the critical current surface density at a tube voltage of 90 kV was 0.98 mA / mm ² . When the window foil 9a having a thickness of 5 × 10 ^-3 mm was used, the critical current surface density at a tube voltage of 70 kV was 0.56 mA / mm ² . When the window foil 9a having a thickness of 5 × 10 ^-3 mm was used, the critical current surface density at a tube voltage of 50 kV was 0.26 mA / mm ² .

FIG. 9 is a diagram showing simulated values of the current surface density of the electron beam irradiator of FIG. 1. FIG. 9 shows the critical current surface density calculated by simulation using a model simulating the electron beam irradiation device 1 for each thickness of the window foil 9a and the tube voltage of the filament unit 2.

As shown in FIG. 9, ^{when the window foil 9a having a thickness of 3 × 10 -3} mm is used, the critical current surface density at a tube voltage of 130 kV is calculated to be ^{5.3 mA / mm 2.} When a window foil 9a having a thickness of 3 × 10 ^-3 mm is used, the critical current surface density at a tube voltage of 120 kV is calculated to be ^{4.9 mA / mm 2.} When a window foil 9a having a thickness of 3 × 10 ^-3 mm is used, the critical current surface density at a tube voltage of 110 kV is calculated to be ^{4.0 mA / mm 2.} When a window foil 9a having a thickness of 3 × 10 ^-3 mm is used, the critical current surface density at a tube voltage of 100 kV is calculated to be ^{3.3 mA / mm 2.} When a window foil 9a having a thickness of 3 × 10 ^-3 mm is used, the critical current surface density at a tube voltage of 90 kV is calculated to be ^{2.6 mA / mm 2.} When a window foil 9a having a thickness of 3 × 10 ^-3 mm is used, the critical current surface density at a tube voltage of 70 kV is calculated to be ^{1.4 mA / mm 2.} When a window foil 9a having a thickness of 3 × 10 ^-3 mm is used, the critical current surface density at a tube voltage of 50 kV is calculated to be ^{0.6 mA / mm 2.}

Further, when the window foil 9a having a thickness of 4 × 10 ^-3 mm is used, the critical current surface density at a tube voltage of 130 kV is calculated to be ^{4.7 mA / mm 2.} When a window foil 9a having a thickness of 4 × 10 ^-3 mm is used, the critical current surface density at a tube voltage of 120 kV is calculated to be ^{3.8 mA / mm 2.} When a window foil 9a having a thickness of 4 × 10 ^-3 mm is used, the critical current surface density at a tube voltage of 110 kV is calculated to be ^{3.1 mA / mm 2.} When a window foil 9a having a thickness of 4 × 10 ^-3 mm is used, the critical current surface density at a tube voltage of 100 kV is calculated to be ^{2.5 mA / mm 2.} When a window foil 9a having a thickness of 4 × 10 ^-3 mm is used, the critical current surface density at a tube voltage of 90 kV is calculated to be ^{1.9 mA / mm 2.} When a window foil 9a having a thickness of 4 × 10 ^-3 mm is used, the critical current surface density at a tube voltage of 70 kV is calculated to be ^{1.0 mA / mm 2.} When a window foil 9a having a thickness of 4 × 10 ^-3 mm is used, the critical current surface density at a tube voltage of 50 kV is calculated to be ^{0.5 mA / mm 2.}

Further, when the window foil 9a having a thickness of 5 × 10 ^-3 mm is used, the critical current surface density at a tube voltage of 130 kV is calculated to be ^{4.0 mA / mm 2.} When a window foil 9a having a thickness of 5 × 10 ^-3 mm is used, the critical current surface density at a tube voltage of 120 kV is calculated to be ^{2.4 mA / mm 2.} When a window foil 9a having a thickness of 5 × 10 ^-3 mm is used, the critical current surface density at a tube voltage of 110 kV is calculated to be ^{2.0 mA / mm 2.} When a window foil 9a having a thickness of 5 × 10 ^-3 mm is used, the critical current surface density at a tube voltage of 100 kV is calculated to be ^{1.6 mA / mm 2.} When a window foil 9a having a thickness of 5 × 10 ^-3 mm is used, the critical current surface density at a tube voltage of 90 kV is calculated to be ^{1.1 mA / mm 2.} When a window foil 9a having a thickness of 5 × 10 ^-3 mm is used, the critical current surface density at a tube voltage of 70 kV is calculated to be ^{0.6 mA / mm 2.} When a window foil 9a having a thickness of 5 × 10 ^-3 mm is used, the critical current surface density at a tube voltage of 50 kV is calculated to be ^{0.3 mA / mm 2.}

FIG. 10 is a diagram showing the relationship between the critical current surface density of FIGS. 8 and 9 and the tube voltage. The horizontal axis of FIG. 10 is the tube voltage (kV) of the filament unit 2, and the vertical axis is the critical current surface density (mA / mm ² ). In FIG. 10, the experimental values of FIG. 8 are shown by solid lines, and the simulation values of FIG. 9 are shown by broken lines. In FIG. 10, the white triangular plot corresponds to the experimental value of the critical current surface density when a window foil 9a having ^{a thickness of 5 × 10 -3 mm is used.} The plot of the filled triangle corresponds to the simulated value of the critical current surface density when the window foil 9a having ^{a thickness of 5 × 10 -3 mm is used.} The white upright square plot corresponds to the simulated value of the critical current surface density when a window foil 9a having a thickness of 4 × 10 ^{-3 mm is used.} The white inclined square plot corresponds to the experimental value of the critical current surface density when the window foil 9a having a thickness of 3 × 10 ^{-3 mm is used.} The sloping square plot of the fill corresponds to the simulated value of the critical current surface density when using a window foil 9a with ^{a thickness of 3 × 10 -3 mm.}

As shown in FIG. 10, the critical current surface density as a whole is about the same as the experimental value and the simulated value with respect to the increase in the tube voltage of the filament unit 2 for each thickness of the window foil 9a. It shows a tendency to increase monotonically. For example, when a window foil 9a having a thickness of 3 × 10 ^-3 mm is used, the experimental value (plot of a white sloping square) and the simulation value (plot of a filled sloping square) of the critical current surface density are obtained. It shows a tendency to monotonically increase with each other in the same tendency as the tube voltage of the filament unit 2 increases. When a window foil 9a having a thickness of 5 × 10 ^-3 mm is used, the experimental value (plot of the white triangle) and the simulation value (plot of the filled triangle) of the critical current surface density are also the filament unit 2. It shows a tendency to increase monotonically with the same tendency as each other with respect to the increase of the tube voltage. From these facts, when a window foil 9a having a thickness of 4 × 10 ^-3 mm is used, the simulated value of the critical current surface density (plot of an upright square in white) has a thickness of 4 × 10 ^-3. It can be considered that the same tendency as the measured value (not shown) of the critical current surface density when the window foil 9a of mm is used is shown.

According to the tendency of the critical current surface density in FIG. 10, if the drive current of the filament unit 2 is set so as to be the current surface density belonging to the lower region of each curve for each thickness of the window foil 9a, the thickness is the same. With respect to the window foil 9a, it can be said that the temperature of the window foil 9a is suppressed from exceeding the allowable temperature, and the possibility that the window foil 9a is damaged by heat is reduced. Therefore, the control unit 50 may control the drive current of the filament unit 2 so that the current surface density decreases as the drive voltage of the filament unit 2 decreases with respect to the window foil 9a having one type of thickness. .. In this case, the window foil 9a may be cooled by the cooling unit 100.

The tendency of monotonous increase in the critical current surface density with respect to the tube voltage of the filament unit 2 can be considered to correspond to, for example, a part of the quadratic function. Therefore, the filament unit is based on ^{the critical current surface density approximation value (mA / mm 2} ) approximated by a quadratic function having a predetermined coefficient according to the thickness of the window foil 9a, with the tube voltage of the filament unit 2 as a variable. The drive current of 2 may be set. The control unit 50 calculates a critical current surface density approximated value approximated by a quadratic function based on the tube voltage of the filament unit 2 (driving voltage of the electron beam generating portion) and the thickness of the window foil 9a, and the calculated critical current. The drive current of the filament unit 2 may be set so as to be equal to or less than the approximate surface density value. The predetermined coefficient can be set so as to be a locus of a downwardly convex quadratic function along a plurality of plots when the thickness of the window foil 9a is uniformly determined in FIG. As a result, even if the drive voltage of the filament unit 2 changes with the thickness of the window foil 9a determined, the drive current of the filament unit 2 can be easily increased by using the approximate value of the critical current surface density approximated by the quadratic function. Can be set.

As a specific example, the control unit 50 sets the drive voltage of the filament unit 2 so that the tube voltage of the filament unit 2 is 130 kV or less when the thickness of the window foil 9a is 3 × 10 ^{-3 mm.} The drive current of the filament unit 2 may be set so that the current surface density in the window foil 9a is 5.3 mA / mm ^{2 or less.} Alternatively, when the thickness of the window foil 9a is 4 × 10 ^-3 mm, the control unit 50 sets the drive voltage of the filament unit 2 so that the tube voltage of the filament unit 2 is 130 kV or less, and the window foil 9a The drive current of the filament unit 2 may be set so that the current surface density in the above is 4.7 mA / mm ^{2 or less.} Alternatively, when the thickness of the window foil 9a is 5 × 10 ^-3 mm, the control unit 50 sets the drive voltage of the filament unit 2 so that the tube voltage of the filament unit 2 is 130 kV or less, and the window foil 9a The drive current of the filament unit 2 may be set so that the current surface density in the above is 4.0 mA / mm ^{2 or less.} In other words, when the thickness of the window foil 9a is 3 × 10 ^-3 mm or more and 5 × 10 ^-3 mm or less, the control unit 50 makes the filament unit 2 so that the tube voltage of the filament unit 2 becomes 130 kV or less. The drive voltage of the filament unit 2 may be set so that the current surface density in the window foil 9a is 5.3 mA / mm ^{2 or less.} When the thickness of the window foil 9a is 4 × 10 ^-3 mm or more and 5 × 10 ^-3 mm or less, the control unit 50 sets the drive voltage of the filament unit 2 so that the tube voltage of the filament unit 2 becomes 130 kV or less. The drive current of the filament unit 2 may be set so that the current surface density in the window foil 9a is 4.7 mA / mm ^{2 or less.}

Alternatively, when the thickness of the window foil 9a is 3 × 10 ^-3 mm, the control unit 50 sets the drive voltage of the filament unit 2 so that the tube voltage of the filament unit 2 is 120 kV or less, and the window foil 9a The drive current of the filament unit 2 may be set so that the current surface density in the above is 4.9 mA / mm ^{2 or less.} Alternatively, when the thickness of the window foil 9a is 4 × 10 ^-3 mm, the control unit 50 sets the drive voltage of the filament unit 2 so that the tube voltage of the filament unit 2 is 120 kV or less, and the window foil 9a The drive current of the filament unit 2 may be set so that the current surface density in the above is 3.8 mA / mm ^{2 or less.} Alternatively, when the thickness of the window foil 9a is 5 × 10 ^-3 mm, the control unit 50 sets the drive voltage of the filament unit 2 so that the tube voltage of the filament unit 2 is 120 kV or less, and the window foil 9a The drive current of the filament unit 2 may be set so that the current surface density in the above is 2.4 mA / mm ^{2 or less.} In other words, when the thickness of the window foil 9a is 3 × 10 ^-3 mm or more and 5 × 10 ^-3 mm or less, the control unit 50 makes the filament unit 2 so that the tube voltage of the filament unit 2 becomes 120 kV or less. The drive voltage of the filament unit 2 may be set so that the current surface density in the window foil 9a is 4.9 mA / mm ^{2 or less.} When the thickness of the window foil 9a is 4 × 10 ^-3 mm or more and 5 × 10 ^-3 mm or less, the control unit 50 sets the drive voltage of the filament unit 2 so that the tube voltage of the filament unit 2 becomes 120 kV or less. The drive current of the filament unit 2 may be set so that the current surface density in the window foil 9a is 3.8 mA / mm ^{2 or less.}

Alternatively, when the thickness of the window foil 9a is 3 × 10 ^-3 mm, the control unit 50 sets the drive voltage of the filament unit 2 so that the tube voltage of the filament unit 2 is 110 kV or less, and the window foil 9a The drive current of the filament unit 2 may be set so that the current surface density in the above is 4.0 mA / mm ^{2 or less.} Alternatively, when the thickness of the window foil 9a is 4 × 10 ^-3 mm, the control unit 50 sets the drive voltage of the filament unit 2 so that the tube voltage of the filament unit 2 is 110 kV or less, and the window foil 9a The drive current of the filament unit 2 may be set so that the current surface density in the above is 3.1 mA / mm ^{2 or less.} Alternatively, when the thickness of the window foil 9a is 5 × 10 ^-3 mm, the control unit 50 sets the drive voltage of the filament unit 2 so that the tube voltage of the filament unit 2 is 110 kV or less, and the window foil 9a The drive current of the filament unit 2 may be set so that the current surface density in the above is 2.0 mA / mm ^{2 or less.} In other words, when the thickness of the window foil 9a is 3 × 10 ^-3 mm or more and 5 × 10 ^-3 mm or less, the control unit 50 makes the filament unit 2 so that the tube voltage of the filament unit 2 becomes 110 kV or less. The drive voltage of the filament unit 2 may be set so that the current surface density in the window foil 9a is 4.0 mA / mm ^{2 or less.} When the thickness of the window foil 9a is 4 × 10 ^-3 mm or more and 5 × 10 ^-3 mm or less, the control unit 50 sets the drive voltage of the filament unit 2 so that the tube voltage of the filament unit 2 becomes 110 kV or less. The drive current of the filament unit 2 may be set so that the current surface density in the window foil 9a is 3.1 mA / mm ^{2 or less.}

Alternatively, when the thickness of the window foil 9a is 3 × 10 ^-3 mm, the control unit 50 sets the drive voltage of the filament unit 2 so that the tube voltage of the filament unit 2 is 100 kV or less, and the window foil 9a The drive current of the filament unit 2 may be set so that the current surface density in the above is 3.3 mA / mm ^{2 or less.} Alternatively, when the thickness of the window foil 9a is 4 × 10 ^-3 mm, the control unit 50 sets the drive voltage of the filament unit 2 so that the tube voltage of the filament unit 2 is 100 kV or less, and the window foil 9a The drive current of the filament unit 2 may be set so that the current surface density in the above is ^{2.5 mA / mm 2 or less.} Alternatively, when the thickness of the window foil 9a is 5 × 10 ^-3 mm, the control unit 50 sets the drive voltage of the filament unit 2 so that the tube voltage of the filament unit 2 is 100 kV or less, and the window foil 9a The drive current of the filament unit 2 may be set so that the current surface density in the above is 1.6 mA / mm ^{2 or less.} In other words, when the thickness of the window foil 9a is 3 × 10 ^-3 mm or more and 5 × 10 ^-3 mm or less, the control unit 50 makes the filament unit 2 so that the tube voltage of the filament unit 2 becomes 100 kV or less. The drive voltage of the filament unit 2 may be set so that the current surface density in the window foil 9a is 3.3 mA / mm ^{2 or less.} When the thickness of the window foil 9a is 4 × 10 ^-3 mm or more and 5 × 10 ^-3 mm or less, the control unit 50 sets the drive voltage of the filament unit 2 so that the tube voltage of the filament unit 2 becomes 100 kV or less. The drive current of the filament unit 2 may be set so that the current surface density in the window foil 9a is 2.5 mA / mm ^{2 or less.}

Alternatively, when the thickness of the window foil 9a is 3 × 10 ^-3 mm, the control unit 50 sets the drive voltage of the filament unit 2 so that the tube voltage of the filament unit 2 is 90 kV or less, and the window foil 9a The drive current of the filament unit 2 may be set so that the current surface density in the above is 2.6 mA / mm ^{2 or less.} Alternatively, when the thickness of the window foil 9a is 4 × 10 ^-3 mm, the control unit 50 sets the drive voltage of the filament unit 2 so that the tube voltage of the filament unit 2 is 90 kV or less, and the window foil 9a The drive current of the filament unit 2 may be set so that the current surface density in the above is 1.9 mA / mm ^{2 or less.} Alternatively, when the thickness of the window foil 9a is 5 × 10 ^-3 mm, the control unit 50 sets the drive voltage of the filament unit 2 so that the tube voltage of the filament unit 2 is 90 kV or less, and the window foil 9a The drive current of the filament unit 2 may be set so that the current surface density in the above is 1.1 mA / mm ^{2 or less.} In other words, when the thickness of the window foil 9a is 3 × 10 ^-3 mm or more and 5 × 10 ^-3 mm or less, the control unit 50 makes the filament unit 2 so that the tube voltage of the filament unit 2 becomes 90 kV or less. The drive voltage of the filament unit 2 may be set so that the current surface density in the window foil 9a is 2.6 mA / mm ^{2 or less.} When the thickness of the window foil 9a is 4 × 10 ^-3 mm or more and 5 × 10 ^-3 mm or less, the control unit 50 sets the drive voltage of the filament unit 2 so that the tube voltage of the filament unit 2 becomes 90 kV or less. The drive current of the filament unit 2 may be set so that the current surface density in the window foil 9a is 1.9 mA / mm ^{2 or less.}

Alternatively, when the thickness of the window foil 9a is 3 × 10 ^-3 mm, the control unit 50 sets the drive voltage of the filament unit 2 so that the tube voltage of the filament unit 2 is 70 kV or less, and the window foil 9a The drive current of the filament unit 2 may be set so that the current surface density in the above is 1.4 mA / mm ^{2 or less.} Alternatively, when the thickness of the window foil 9a is 4 × 10 ^-3 mm, the control unit 50 sets the drive voltage of the filament unit 2 so that the tube voltage of the filament unit 2 is 70 kV or less, and the window foil 9a The drive current of the filament unit 2 may be set so that the current surface density in the above is 1.0 mA / mm ^{2 or less.} Alternatively, when the thickness of the window foil 9a is 5 × 10 ^-3 mm, the control unit 50 sets the drive voltage of the filament unit 2 so that the tube voltage of the filament unit 2 is 70 kV or less, and the window foil 9a The drive current of the filament unit 2 may be set so that the current surface density in the above is 0.6 mA / mm ^{2 or less.} In other words, when the thickness of the window foil 9a is 3 × 10 ^-3 mm or more and 5 × 10 ^-3 mm or less, the control unit 50 makes the filament unit 2 so that the tube voltage of the filament unit 2 becomes 70 kV or less. The drive voltage of the filament unit 2 may be set so that the current surface density of the window foil 9a is 1.4 mA / mm ^{2 or less.} When the thickness of the window foil 9a is 4 × 10 ^-3 mm or more and 5 × 10 ^-3 mm or less, the control unit 50 sets the drive voltage of the filament unit 2 so that the tube voltage of the filament unit 2 becomes 70 kV or less. The drive current of the filament unit 2 may be set so that the current surface density in the window foil 9a is 1.0 mA / mm ^{2 or less.}

Alternatively, when the thickness of the window foil 9a is 3 × 10 ^-3 mm, the control unit 50 sets the drive voltage of the filament unit 2 so that the tube voltage of the filament unit 2 is 50 kV or less, and the window foil 9a The drive current of the filament unit 2 may be set so that the current surface density in the above is 0.6 mA / mm ^{2 or less.} Alternatively, when the thickness of the window foil 9a is 4 × 10 ^-3 mm, the control unit 50 sets the drive voltage of the filament unit 2 so that the tube voltage of the filament unit 2 is 50 kV or less, and the window foil 9a The drive current of the filament unit 2 may be set so that the current surface density in the above is 0.5 mA / mm ^{2 or less.} Alternatively, when the thickness of the window foil 9a is 5 × 10 ^-3 mm, the control unit 50 sets the drive voltage of the filament unit 2 so that the tube voltage of the filament unit 2 is 50 kV or less, and the window foil 9a The drive current of the filament unit 2 may be set so that the current surface density in the above is 0.3 mA / mm ^{2 or less.} In other words, when the thickness of the window foil 9a is 3 × 10 ^-3 mm or more and 5 × 10 ^-3 mm or less, the control unit 50 makes the filament unit 2 so that the tube voltage of the filament unit 2 becomes 50 kV or less. The drive voltage of the filament unit 2 may be set so that the current surface density of the window foil 9a is 0.6 mA / mm ^{2 or less.} When the thickness of the window foil 9a is 4 × 10 ^-3 mm or more and 5 × 10 ^-3 mm or less, the control unit 50 sets the drive voltage of the filament unit 2 so that the tube voltage of the filament unit 2 becomes 50 kV or less. The drive current of the filament unit 2 may be set so that the current surface density in the window foil 9a is 0.5 mA / mm ^{2 or less.}

FIG. 11 is a diagram showing the relationship between the critical current surface density of FIGS. 8 and 9 and the thickness of the window foil 9a. The horizontal axis of FIG. 11 is the thickness of the window foil 9a (10 ^-3 mm), and the vertical axis is the critical current surface density (mA / mm ² ). In FIG. 11, the experimental values of FIG. 8 are shown by solid lines, and the simulation values of FIG. 9 are shown by broken lines. In FIG. 11, the white circle plot corresponds to the experimental value of the critical current surface density when the tube voltage of the filament unit 2 is 130 kV. The filled circle plot corresponds to the simulated value of the critical current surface density when the tube voltage of the filament unit 2 is 130 kV. The plot of "+" corresponds to the simulated value of the critical current surface density when the tube voltage of the filament unit 2 is 120 kV. The plot of "x" corresponds to the simulated value of the critical current surface density when the tube voltage of the filament unit 2 is 1100 kV. The plot of "-mark" corresponds to the simulated value of the critical current surface density when the tube voltage of the filament unit 2 is 100 kV. The filled triangle plot corresponds to the experimental value of the critical current surface density when the tube voltage of the filament unit 2 is 90 kV. The white triangular plot corresponds to the simulated value of the critical current surface density when the tube voltage of the filament unit 2 is 90 kV. The upright square plot of the fill corresponds to the experimental value of the critical current surface density when the tube voltage of the filament unit 2 is 70 kV. The white upright square plot corresponds to the simulated value of the critical current surface density when the tube voltage of the filament unit 2 is 70 kV. The sloping square plot of the fill corresponds to the experimental value of the critical current surface density when the tube voltage of the filament unit 2 is 50 kV. The white slanted square plot corresponds to the simulated value of the critical current surface density when the tube voltage of the filament unit 2 is 50 kV.

As shown in FIG. 11, the critical current surface density as a whole is about the same as the experimental value and the simulated value with respect to the increase in the thickness of the window foil 9a for each tube voltage of the filament unit 2. It shows a tendency to decrease monotonically. For example, when the tube voltage of the filament unit 2 is 130 kV, the experimental value of the critical current surface density (plot of white circles) and the simulated value of the simulated limit current surface density (plot of filled circles) are the window foil 9a. It shows a tendency to decrease monotonically with the same tendency as the increase in thickness. When the tube voltage of the filament unit 2 is 90 kV, the experimental value of the critical current surface density (plot of the filled triangle) and the simulated value of the simulated limit current surface density (plot of the white triangle) are the window foil 9a. It shows a tendency to decrease monotonically with the same tendency as the increase in thickness. When the tube voltage of the filament unit 2 is 70 kV, the experimental value of the critical current surface density (filled upright square) and the simulated value of the critical current surface density (white upright square) are window foils. It shows a tendency to monotonically decrease with the same tendency as each other with respect to the increase in the thickness of 9a. When the tube voltage of the filament unit 2 is 50 kV, the experimental value of the critical current surface density (filled inclined square) and the simulated value of the critical current surface density (plot of the white inclined square) are the window foil. It shows a tendency to monotonically decrease with the same tendency as each other with respect to the increase in the thickness of 9a.

The tendency of the monotonous decrease in the critical current surface density with respect to the thickness of the window foil 9a can be considered to correspond to, for example, a part of a linear function having a negative slope with respect to the increase in the thickness of the window foil 9a. Therefore, the thickness of the window foil 9a is used as a variable, and the critical current surface density approximation value (mA / mm ² ) approximated by a linear function having a negative slope of the magnitude corresponding to the tube voltage of the filament unit 2 is used. , The drive current of the filament unit 2 may be set. In this case, the control unit 50 calculates and calculates a critical current surface density approximated value approximated by a linear function based on the tube voltage of the filament unit 2 (driving voltage of the electron beam generating unit) and the thickness of the window foil 9a. The drive current of the filament unit 2 may be set so as to be equal to or less than the approximate value of the critical current surface density. The slope and intercept can be set so as to be a locus of a linear function that follows a plurality of plots when the tube voltage of the filament unit 2 is defined in the same manner in FIG. For example, in the range where the tube voltage of the filament unit 2 is 120 kV or less, the higher the tube voltage of the filament unit 2, the larger the magnitude of the negative slope may be. As a result, even if the thickness of the window foil 9a changes at the drive voltage of the filament unit 2 that has been determined, the drive current of the filament unit 2 can be easily increased by using the approximate value of the critical current surface density approximated by the linear function. Can be set.

Subsequently, the manufacturing method of the electron beam irradiation device 1 will be described. FIG. 12 is a flowchart showing a method of manufacturing an electron beam irradiation device. Each step shown in FIG. 12 is executed as a part of a step of determining a controllable range of the control unit 50, for example, when manufacturing the electron beam irradiation device 1 shown in FIG.

As shown in FIG. 12, in the manufacturing method of the electron beam irradiating device 1, for example, a step S01 (fourth step) in which a window foil 9a having a predetermined thickness is prepared and a range of a driving voltage of the filament unit 2 are set. Step S02 (first step), step S03 (second step) for specifying the area of the incident region (electron beam transmission region 9f) of the electron beam EB in the window foil 9a, and the current surface density in the window foil 9a are predetermined. The step S04 (third step) of setting the range of the drive current of the filament unit 2 so as to be equal to or less than the limit current surface density of is provided.

In step S01, for example, ^{a window foil 9a having a thickness of 2 × 10 -3} mm or more and 1 × 10 ⁻² mm or less is prepared. In step S01, the operator may prepare a window foil 9a having ^{a thickness of 4 × 10 -3} mm or more and 5 × 10 ^{-3 mm or less cut into the shape of the window foil 9a.} In step S01 here, the operator prepares, for example, a titanium foil having ^{a thickness of 3 × 10 -3} mm, 4 × 10 ^-3 mm, or 5 × 10 ^{-3 mm.}

In step S02, the operator sets the range of the drive voltage of the filament unit 2 by the control unit 50. The range of the drive voltage of the filament unit 2 means the range of the voltage that can be applied to the filament unit 2 when the electron beam irradiation device 1 is used. The operator sets the range of the drive voltage of the filament unit 2 so as to realize the intensity of the electron beam EB required according to the application of the electron beam irradiation device 1.

In step S03, more specifically, the area specifying process shown in FIG. 13 may be performed. FIG. 13 is a flowchart showing the area specifying process of FIG. As shown in FIG. 13, in the area specifying process, as an example, the step S11 in which the fluorescent member is arranged instead of the window foil 9a and the area of the light emitting region that emits light due to the incident of the electron beam EB in the fluorescent member are set as the incident region. The step S12 to acquire the area and the step S13 to remove the fluorescent member and arrange the window foil 9a after acquiring the area of the light emitting region are included.

In step S11, the operator arranges the fluorescent member in place of the window foil 9a in the window member 9. In step S12, the operator causes the electron beam EB to be incident on the fluorescent member in a state where the fluorescent member is arranged. As a result, the region where the electron beam EB is incident on the fluorescent member emits light. The operator acquires the area of the light emitting region that emits light due to the incident of the electron beam EB as the area of the incident region (the area of the electron beam transmitting region 9f). After acquiring the area in step S12, the predetermined critical current surface density is obtained by removing the fluorescent member and arranging the window foil 9a to gradually increase the drive current of the filament unit 2, and the window foil 9a is heated by heat. It can be obtained as the current surface density when it is damaged. The operator may omit the step S11 and acquire the area of the incident region by using an object that emits light due to the incident of the electron beam EB without removing the window foil 9a.

In step S13, the operator removes the fluorescent member and arranges the window foil 9a. When the step S11 is omitted, instead of removing the fluorescent member and arranging the window foil 9a, an object that emits light due to the incident of the electron beam EB is removed. After that, the operator exhausts the air from the vacuum container 3 so that the inside of the vacuum container 3 becomes a vacuum.

Returning to FIG. 12, in step S04, the operator sets the range of the drive current of the filament unit 2 so that the current surface density in the window foil 9a is equal to or less than the predetermined limit current surface density. The range of the drive current of the filament unit 2 means the range of the drive current that can be applied to the filament unit 2 under the condition of the drive voltage of the filament unit 2 that belongs to the range set in step S02. For example, the operator selects the drive voltage of the filament unit 2 to a predetermined tube voltage so as to belong to the range set in step S02, and sets the critical current surface density according to the tube voltage and the thickness of the window foil 9a. For example, it is calculated from FIG. 8 or FIG. 9, and the range of the drive current of the filament unit 2 is set so that the current surface density in the window foil 9a is equal to or less than the limit current surface density.

As an example, in step S04, even if the upper limit of the drive current range is set smaller as the upper limit of the drive voltage range set in step S02 becomes smaller for the window foil 9a of one type of thickness. good.

Specifically, when the window foil 9a having a thickness of 3 × 10 ^-3 mm is prepared in step S01, the filament unit 2 by the control unit 50 is set so that the tube voltage of the filament unit 2 becomes 130 kV or less in step S02. The drive voltage range of the filament unit 2 may be set so that the current surface density in the window foil 9a is 5.3 mA / mm ^{2 or less in step S04.} In step S02, the range of the drive voltage of the filament unit 2 by the control unit 50 is set so that the tube voltage of the filament unit 2 becomes 120 kV or less, and in step S04, the current surface density in the window foil 9a is 4.9 mA / mm ² or less. The range of the drive current of the filament unit 2 may be set so as to be. In step S02, the range of the drive voltage of the filament unit 2 by the control unit 50 is set so that the tube voltage of the filament unit 2 becomes 110 kV or less, and in step S04, the current surface density in the window foil 9a is 4.0 mA / mm ² or less. The range of the drive current of the filament unit 2 may be set so as to be. In step S02, the range of the drive voltage of the filament unit 2 by the control unit 50 is set so that the tube voltage of the filament unit 2 becomes 100 kV or less, and in step S04, the current surface density in the window foil 9a is 3.3 mA / mm ² or less. The range of the drive current of the filament unit 2 may be set so as to be. In step S02, the range of the drive voltage of the filament unit 2 by the control unit 50 is set so that the tube voltage of the filament unit 2 becomes 90 kV or less, and in step S04, the current surface density in the window foil 9a is 2.6 mA / mm ² or less. The range of the drive current of the filament unit 2 may be set so as to be. In step S02, the range of the drive voltage of the filament unit 2 by the control unit 50 is set so that the tube voltage of the filament unit 2 becomes 70 kV or less, and in step S04, the current surface density in the window foil 9a is 1.4 mA / mm ² or less. The range of the drive current of the filament unit 2 may be set so as to be. In step S02, the range of the drive voltage of the filament unit 2 by the control unit 50 is set so that the tube voltage of the filament unit 2 becomes 50 kV or less, and in step S04, the current surface density in the window foil 9a is 0.6 mA / mm ² or less. The range of the drive current of the filament unit 2 may be set so as to be.

Alternatively, when the window foil 9a having a thickness of 4 × 10 ^-3 mm is prepared in step S01, the drive voltage of the filament unit 2 by the control unit 50 is set so that the tube voltage of the filament unit 2 becomes 130 kV or less in step S02. The range of the drive current of the filament unit 2 may be set so that the current surface density in the window foil 9a is 4.7 mA / mm ^{2 or less in step S04.} In step S02, the range of the drive voltage of the filament unit 2 by the control unit 50 is set so that the tube voltage of the filament unit 2 becomes 120 kV or less, and in step S04, the current surface density in the window foil 9a is 3.8 mA / mm ² or less. The range of the drive current of the filament unit 2 may be set so as to be. In step S02, the range of the drive voltage of the filament unit 2 by the control unit 50 is set so that the tube voltage of the filament unit 2 becomes 110 kV or less, and in step S04, the current surface density in the window foil 9a is 3.1 mA / mm ² or less. The range of the drive current of the filament unit 2 may be set so as to be. In step S02, the range of the drive voltage of the filament unit 2 by the control unit 50 is set so that the tube voltage of the filament unit 2 becomes 100 kV or less, and in step S04, the current surface density in the window foil 9a is 2.5 mA / mm ² or less. The range of the drive current of the filament unit 2 may be set so as to be. In step S02, the range of the drive voltage of the filament unit 2 by the control unit 50 is set so that the tube voltage of the filament unit 2 becomes 90 kV or less, and in step S04, the current surface density in the window foil 9a is 1.9 mA / mm ² or less. The range of the drive current of the filament unit 2 may be set so as to be. In step S02, the range of the drive voltage of the filament unit 2 by the control unit 50 is set so that the tube voltage of the filament unit 2 becomes 70 kV or less, and in step S04, the current surface density in the window foil 9a is 1.0 mA / mm ² or less. The range of the drive current of the filament unit 2 may be set so as to be. In step S02, the range of the drive voltage of the filament unit 2 by the control unit 50 is set so that the tube voltage of the filament unit 2 becomes 50 kV or less, and in step S04, the current surface density in the window foil 9a is 0.5 mA / mm ² or less. The range of the drive current of the filament unit 2 may be set so as to be.

Alternatively, when the window foil 9a having a thickness of 5 × 10 ^-3 mm is prepared in step S01, the drive voltage of the filament unit 2 by the control unit 50 is set so that the tube voltage of the filament unit 2 becomes 130 kV or less in step S02. The range of the drive current may be set so that the current surface density in the window foil 9a is 4.0 mA / mm ^{2 or less in the third step.} In step S02, the range of the drive voltage of the filament unit 2 by the control unit 50 is set so that the tube voltage of the filament unit 2 becomes 120 kV or less, and in step S04, the current surface density in the window foil 9a is 2.4 mA / mm ² or less. The range of the drive current of the filament unit 2 may be set so as to be. In step S02, the range of the drive voltage of the filament unit 2 by the control unit 50 is set so that the tube voltage of the filament unit 2 becomes 110 kV or less, and in step S04, the current surface density in the window foil 9a is 2.0 mA / mm ² or less. The range of the drive current of the filament unit 2 may be set so as to be. In step S02, the range of the drive voltage of the filament unit 2 by the control unit 50 is set so that the tube voltage of the filament unit 2 becomes 100 kV or less, and in step S04, the current surface density in the window foil 9a is 1.6 mA / mm ² or less. The range of the drive current of the filament unit 2 may be set so as to be. In step S02, the range of the drive voltage of the filament unit 2 by the control unit 50 is set so that the tube voltage of the filament unit 2 becomes 90 kV or less, and in the third step, the current surface density in the window foil 9a is 1.1 mA / mm ^2. The drive current range may be set as follows. In step S02, the range of the drive voltage of the filament unit 2 by the control unit 50 is set so that the tube voltage of the filament unit 2 becomes 70 kV or less, and in the third step, the current surface density in the window foil 9a is 0.6 mA / mm ^2. The drive current range may be set as follows. In step S02, the range of the drive voltage of the filament unit 2 by the control unit 50 is set so that the tube voltage of the filament unit 2 becomes 50 kV or less, and in the third step, the current surface density in the window foil 9a is 0.3 mA / mm ^2. The drive current range may be set as follows.

By each of the above steps, the electron beam irradiation device 1 is manufactured in a usable state.

As described above, the electron beam irradiation device 1 is set so that the drive voltage and drive current of the filament unit 2 by the control unit 50 can be suppressed to ^{5.3 mA / mm 2 or less in the current surface density of the window foil 9a.} To. As a result, for example, the temperature rise of the window foil 9a is suppressed within an appropriate range as compared with the case where the drive voltage and the drive current are set without such limitation of the current surface density, so that the life of the window foil 9a can be extended. Can be planned. In addition, the cooling of the window foil 9a is also streamlined.

The current surface density is a value obtained by dividing the tube current of the filament unit 2 by the area of the incident region of the electron beam EB in the window foil 9a. As a result, since the current surface density using the area value of the electron beam transmission region 9f in the window foil 9a is used, the electrons are compared with the case of using the current density using the value of the distance in one direction in the electron beam transmission region 9f. The life of the window foil 9a can be effectively extended for the entire line transmission region 9f.

The control unit 50 controls the drive current of the window foil 9a having a thickness of one type so that the current surface density decreases as the drive voltage decreases. For example, when the thickness of the window foil 9a is 3 × 10 ^-3 mm or more and 5 × 10 ^-3 mm or less, the control unit 50 drives the filament unit 2 so that the tube voltage of the filament unit 2 becomes 130 kV or less. The voltage may be set and the drive current of the filament unit 2 may be set so that the current surface density in the window foil 9a is 5.3 mA / mm ^{2 or less.} Alternatively, when the thickness of the window foil 9a is 4 × 10 ^-3 mm or more and 5 × 10 ^-3 mm or less, the control unit 50 drives the filament unit 2 so that the tube voltage of the filament unit 2 becomes 130 kV or less. The voltage may be set and the drive current of the filament unit 2 may be set so that the current surface density in the window foil 9a is 4.7 mA / mm ^{2 or less.} Alternatively, when the thickness of the window foil 9a is 5 × 10 ^-3 mm, the control unit 50 sets the drive voltage of the filament unit 2 so that the tube voltage of the filament unit 2 is 130 kV or less, and the window foil 9a is set. The drive current of the filament unit 2 may be set so that the current surface density in the above is 4.0 mA / mm ^{2 or less.} When the drive voltage becomes small, it becomes difficult for the electron beam EB to pass through the window member 9, so that the current surface density tends to increase. However, by controlling the drive current so that the current surface density becomes small, the window foil 9a is overheated. Can be suppressed.

The manufacturing method of the electron beam irradiation device is set so that the drive voltage and drive current of the filament unit 2 by the control unit 50 are suppressed so that the current surface density in the window foil 9a is suppressed to the limit current surface density or less. As a result, for example, the temperature rise of the window foil 9a is suppressed within an appropriate range as compared with the case where the drive voltage and the drive current are set without such limitation of the current surface density, so that the cooling of the window foil 9a is made more efficient. Will be done. Therefore, the life of the window foil 9a can be extended.

In the method for manufacturing the electron beam irradiating device, in step S03, the area of the light emitting region that emits light due to the incident of the electron beam EB in the fluorescent member and the step S11 in which the fluorescent member is arranged instead of the window foil 9a is set to the electron beam transmitting region 9f. Includes step S12 to be acquired as the area of the light emitting region, and step S13 to remove the fluorescent member and arrange the window foil 9a after acquiring the area of the light emitting region. As a result, since the current surface density using the area value of the electron beam transmission region 9f in the window foil 9a is used, the electrons are compared with the case of using the current density using the value of the distance in one direction in the electron beam transmission region 9f. The life of the window foil 9a can be effectively extended for the entire line transmission region 9f. Further, the electron beam transmission region 9f can be easily specified by using the light emitting region of the fluorescent member.

The method for manufacturing the electron beam irradiation apparatus includes step S01 for preparing a window foil 9a having ^{a thickness of 2 × 10 -3} mm or more and 10 × 10 ^{-3 mm or less.} In step S04, the upper limit value of the drive current range is set smaller as the upper limit value of the drive voltage range set in step S02 becomes smaller for the window foil 9a having one type of thickness. For example, when the window foil 9a having a thickness of 3 × 10 ^-3 mm or more and 5 × 10 ^-3 mm or less is prepared in step S01, the control unit is set so that the tube voltage of the filament unit 2 is 130 kV or less in step S02. The range of the drive voltage of the filament unit 2 by 50 may be set, and the range of the drive current may be set so that the ^{current surface density in the window foil 9a is 5.3 mA / mm 2 or less in step S04.} When the window foil 9a having a thickness of 4 × 10 ^-3 mm or more and 5 × 10 ^-3 mm or less is prepared in step S01, the control unit 50 adjusts the tube voltage of the filament unit 2 to 130 kV or less in step S02. The range of the drive voltage of the filament unit 2 may be set, and the range of the drive current may be set so that the current surface density in the window foil 9a is 4.7 mA / mm ^{2 or less in step S04.} When the window foil 9a having a thickness of 5 × 10 ^-3 mm is prepared in step S01, the range of the drive voltage of the filament unit 2 by the control unit 50 is set so that the tube voltage of the filament unit 2 becomes 130 kV or less in step S02. May be set, and the range of the drive current may be set so that the current surface density in the window foil 9a is 4.0 mA / mm ^{2 or less in step S04.} As a result, when the drive voltage becomes small, it becomes difficult for the electron beam EB to pass through the window member 9, so that the current surface density tends to increase. Therefore, by setting the upper limit of the drive current range to a small value, it is possible to suppress the increase in the current surface density and suppress the temperature rise of the window foil 9a within an appropriate range.

[Second Embodiment]
FIG. 14 is a side sectional view of the electron beam irradiation device 1A according to the second embodiment. In the electron beam irradiation device 1A as shown in FIG. 14, instead of the electron beam irradiation device 1, the current in the window foil 9a is applied while the window member 9 and the cooling unit 100 exemplified in the first embodiment are applied. It is possible to set the drive voltage and drive current of the filament unit 2 by the control unit 50A so that the surface density is suppressed to 5.3 mA / mm ^{2 or less.}

As shown in FIG. 14, the electron beam irradiator 1A airtightly closes the chamber (housing portion) 30 forming the electron beam passing region 20 and the rear end 20a of the electron beam passing region 20. It includes an attached electron gun (electron beam generating portion) 40, and a window member 9 airtightly attached to the chamber 30 so as to close the front end 20b of the electron beam passing region 20. The electron beam EB generated by the electron gun 40 travels forward in the electron beam passing region 20 in the Z-axis direction, passes through the window member 9, and is emitted to the outside. The side on which the electron beam EB is irradiated by the electron beam irradiation device 1A is the front side, and the opposite side is the rear side.

The chamber 30 has a metal column 31 to which the electron gun 40 is attached. The cylindrical portion 31 is provided with an alignment coil 21 and a focusing coil 22. The electron beam EB emitted from the electron gun 40 is adjusted by the alignment coil 21 so that the center line of the electron beam EB coincides with the center line CL of the electron beam passing region 20, and then the window member 9 is adjusted by the focusing coil 22. Is focused on. The cylindrical portion 31 is provided with an exhaust pipe 23 to which a vacuum pump is connected, whereby the inside of the chamber 30 (that is, the electron beam passing region 20) is evacuated.

The chamber 30 has a deflection tube (housing portion) 32. The deflection tube 32 has, for example, a square columnar outer shape. The cross section of the electron beam passing region 24, which is a portion of the electron beam passing region 20 formed by the deflection tube 32, has a rectangular shape with the Y-axis direction as the longitudinal direction. A deflection coil 25 for deflecting the electron beam EB passing through the inside of the deflection tube 32 is attached to the outside of the deflection tube 32. The electron beam EB focused by the focusing coil 22 and passing through the electron beam passing region 24 is deflected in the Y-axis direction by the deflection coil 25.

Further, the chamber 30 has a scanning tube (housing portion) 33 fixed to the front end surface of the deflection tube 32. The scanning tube 33 has a square columnar outer shape that expands toward the front side. The cross section of the electron beam passing region 26, which is a portion of the electron beam passing region 20 formed by the scanning tube 33, has a rectangular shape with the Y-axis direction as the longitudinal direction. A flange 34 is provided at the front end of the scanning tube 33.

The window member 9 is fixed to the scanning tube 33 so as to cover and seal the opening 20c of the front end 20b of the electron beam passing region 20. The scanning tube 33 and the window member 9 are airtightly fixed by, for example, a plurality of bolts in a state where the flange 34 and the window flange 9c are in contact with each other via the sealing material 9d.

The electron beam irradiation device 1A includes a control unit 50A that controls the electron gun 40 so that the temperature of the window foil 9a becomes appropriate. The detailed description of the control unit 50A is the same as the description of the control unit 50 disclosed in the first embodiment except that the filament unit 2 in the first embodiment is replaced with the electron gun 40, and thus the description is duplicated. Is omitted.

The detailed configuration of the window member 9 and the cooling unit 100 of the second embodiment is the main part of the configuration of the window member 9 of the first embodiment, except for the configuration change such as the shape and dimensions accompanying the attachment to the flange 34. Since it is the same as the above, the duplicate description will be omitted.

Regarding the method of manufacturing the electron beam irradiation device 1A, the window member 9 in which each step shown in FIGS. 12 and 13 is arranged in the opening 20c with respect to the electron beam irradiation device 1A shown in FIG. 14, for example. Is carried out by a worker in the manufacture of the electron beam irradiation device 1A in the situation of preparing the electron beam irradiation device 1A. The details of the manufacturing method of the electron beam irradiation device 1A are the same as those of the steps shown in FIGS. 12 and 13, except that the filament unit 2 is replaced with the electron gun 40 in step S04, and thus the overlapping description will be omitted.

In the electron beam irradiating device 1A described above, similarly to the electron beam irradiating device 1, the electron beam irradiating device 1A has a driving voltage and a driving current of the electron gun 40 by the control unit 50A, and a current surface density of the window foil 9a is 5. It is set so that it can be suppressed to ³ mA / mm 2 or less. As a result, for example, overheating of the window foil 9a is suppressed as compared with the case where the drive voltage and the drive current are set without such limitation of the current surface density, so that the cooling of the window foil 9a is made more efficient. Therefore, the life of the window foil 9a can be extended.

The current surface density is a value obtained by dividing the tube current of the electron gun 40 by the area of the incident region of the electron beam EB in the window foil 9a. As a result, since the current surface density using the area value of the electron beam transmission region 9f in the window foil 9a is used, the electrons are compared with the case of using the current density using the value of the distance in one direction in the electron beam transmission region 9f. The life of the window foil 9a can be effectively extended for the entire line transmission region 9f.

The control unit 50A controls the drive current for the window foil 9a having one type of thickness so that the current surface density decreases as the drive voltage decreases. For example, when the thickness of the window foil 9a is 3 × 10 ^-3 mm, the control unit 50A sets the drive voltage of the electron gun 40 so that the tube voltage of the electron gun 40 is 130 kV or less, and the window foil 9a is set. The drive current of the electron gun 40 may be set so that the current surface density in the electron gun 40 is 5.3 mA / mm ^{2 or less.} Alternatively, when the thickness of the window foil 9a is 4 × 10 ^-3 mm, the control unit 50A sets the drive voltage of the electron gun 40 so that the tube voltage of the electron gun 40 is 130 kV or less, and the window foil 9a The drive current of the electron gun 40 may be set so that the current surface density in the electron gun 40 is 4.7 mA / mm ^{2 or less.} Alternatively, when the thickness of the window foil 9a is 5 × 10 ^-3 mm, the control unit 50A sets the drive voltage of the electron gun 40 so that the tube voltage of the electron gun 40 is 130 kV or less, and the window foil 9a The drive current of the electron gun 40 may be set so that the current surface density in the electron gun 40 is 4.0 mA / mm ^{2 or less.} As a result, when the drive voltage becomes small, it becomes difficult for the electron beam EB to pass through the window member 9, so that the current surface density tends to increase. Therefore, by controlling the drive current so that the current surface density becomes small, overheating of the window foil 9a can be suppressed.

The manufacturing method of the electron beam irradiation device 1A is set so that the drive voltage and drive current of the electron gun 40 by the control unit 50A are suppressed so that the current surface density in the window foil 9a is suppressed to the limit current surface density or less. As a result, for example, the temperature rise of the window foil 9a is suppressed within an appropriate range as compared with the case where the drive voltage and the drive current are set without such limitation of the current surface density, so that the life of the window foil 9a can be extended. Can be planned. In addition, the cooling of the window foil 9a is also streamlined.

In the method for manufacturing the electron beam irradiation device 1A, in step S03, the area of the light emitting region that emits light due to the incident of the electron beam EB in the fluorescent member is the electron beam transmission region in step S11 in which the fluorescent member is arranged instead of the window foil 9a. It includes a step S12 acquired as the area of 9f, and a step S13 of removing the fluorescent member and arranging the window foil 9a after acquiring the area of the light emitting region. As a result, since the current surface density using the area value of the electron beam transmission region 9f in the window foil 9a is used, the electrons are compared with the case of using the current density using the value of the distance in one direction in the electron beam transmission region 9f. The life of the window foil 9a can be effectively extended for the entire line transmission region 9f. Further, the electron beam transmission region 9f can be easily specified by using the light emitting region of the fluorescent member.

The manufacturing method of the electron beam irradiating device 1A includes a step S01 for preparing a window foil 9a having ^{a thickness of 2 × 10 -3} mm or more and 1 × 10 ^{−2 mm or less.} In step S04, the upper limit value of the drive current range is set smaller as the upper limit value of the drive voltage range set in step S02 becomes smaller for the window foil 9a having one type of thickness. For example, when the window foil 9a having a thickness of 3 × 10 ^-3 mm or more and 5 × 10 ^-3 mm or less is prepared in step S01, the tube voltage of the electron gun 40 is controlled to be 130 kV or less in step S02. The range of the drive voltage of the electron gun 40 by the portion 50A may be set, and in step S04, the range of the drive current may be set so that the ^{current surface density in the window foil 9a is 5.3 mA / mm 2 or less.} When the window foil 9a having a thickness of 4 × 10 ^-3 mm or more and 5 × 10 ^-3 mm or less is prepared in step S01, in step S02, the control unit 50A is set so that the tube voltage of the electron gun 40 is 130 kV or less. In step S04, the range of the drive current may be set so that the current surface density in the window foil 9a is 4.7 mA / mm ^{2 or less.} When the window foil 9a having a thickness of 5 × 10 ^-3 mm is prepared in step S01, in step S02, the driving voltage of the electron gun 40 by the control unit 50A is set so that the tube voltage of the electron gun 40 is 130 kV or less. The range may be set, and in step S04, the range of the drive current may be set so that the current surface density in the window foil 9a is 4.0 mA / mm ^{2 or less.} As a result, when the drive voltage becomes small, it becomes difficult for the electron beam EB to pass through the window member 9, so that the current surface density tends to increase. Therefore, by setting the upper limit of the drive current range to a small value, it is possible to suppress an increase in the current surface density and suppress an increase in the temperature of the window foil 9a within an appropriate range.

[Modification example]
Although the embodiments according to the present invention have been described above, the present invention is not limited to the above-described embodiments.

In the first and second embodiments, the current surface density is a value obtained by dividing the tube current of the filament unit 2 or the electron gun 40 by the area of the incident region of the electron beam EB in the window foil 9a. , Not limited to this. For example, the current surface density may be a value obtained by dividing the drive current of the filament unit 2 or the electron gun 40 by the area of the incident region of the electron beam EB in the window foil 9a.

In the first and second embodiments, the control unit 50 and the control unit 50A control the drive current so that the current surface density decreases as the drive voltage decreases with respect to the window foil 9a having one type of thickness. However, it is not limited to this. For example, for a window foil 9a of one type of thickness, the drive current is controlled so that the ^{current surface density of the window foil 9a is a constant predetermined value of 5.3 mA / mm 2 or less regardless of the drive voltage.} You may.

At least a part of the above-described embodiments and various modifications may be arbitrarily combined.

1,1A ... Electron beam irradiator, 2 ... Filament unit (electron beam generator), 3 ... Vacuum container (housing), 3a, 20c ... Opening, 9 ... Window member (electron beam irradiation window), 9a ... Window foil (window foil member), 9f ... electron beam transmission region (incident region), 30 ... chamber (housing), 32 ... deflection tube (housing), 33 ... scanning tube (housing), 40 ... electron gun ( Electron beam generator), EB ... Electron beam.

Claims (16)

The electron beam generator that generates the electron beam and the electron beam generator
A housing portion provided with an opening for passing the electron beam generated from the electron beam generating portion, and a housing portion.
An electron beam irradiation window portion arranged in the opening portion and having a window foil member for transmitting the electron beam passing through the opening portion, and an electron beam irradiation window portion.
A control unit that controls the electron beam generation unit is provided.
The window foil member is a foil member containing titanium as a main component.
The thickness of the window foil member is 2 × 10 ^-3 mm or more and 1 × 10 ^-2 mm or less.
The control unit sets the drive voltage of the electron beam generating unit so that the tube voltage of the electron beam generating unit is 40 kV or more and 150 kV or less, and the current surface density in the window foil member is 5.3 mA / mm ^2. An electron beam irradiator that sets the drive current of the electron beam generating unit so as to be as follows. The electron beam irradiation device according to claim 1, wherein the current surface density is a value obtained by dividing the tube current of the electron beam generating portion by the area of the incident region of the electron beam in the window foil member. The first or second aspect of the present invention, wherein the control unit controls the drive current so that the current surface density decreases as the drive voltage decreases with respect to the window foil member of one type and the thickness. Electron beam irradiation device. The control unit obtains an approximate value of the critical current surface density approximated by a quadratic function using the drive voltage of the electron beam generator as a variable, based on the drive voltage of the electron beam generator and the thickness of the window foil member. The electron beam irradiating device according to claim 3, wherein the driving current of the electron beam generating unit is set so as to be calculated and equal to or less than the calculated limit current surface density approximate value. The control unit calculates a critical current surface density approximation value approximated by a linear function with the thickness of the window foil member as a variable, based on the drive voltage of the electron beam generating unit and the thickness of the window foil member. The electron beam irradiation device according to any one of claims 1 to 4, wherein the drive current of the electron beam generating unit is set so as to be equal to or less than the calculated critical current surface density approximate value. The thickness of the window foil member is 3 × 10 ^-3 mm or more and 5 × 10 ^-3 mm or less.
The control unit sets the drive voltage of the electron beam generating unit so that the tube voltage of the electron beam generating unit is 130 kV or less, and the current surface density of the window foil member is 5.3 mA / mm ² or less. The electron beam irradiating device according to any one of claims 1 to 5, wherein the driving current of the electron beam generating unit is set as described above. The thickness of the window foil member is 4 × 10 ^-3 mm or more and 5 × 10 ^-3 mm or less.
The control unit sets the drive voltage of the electron beam generating unit so that the tube voltage of the electron beam generating unit is 130 kV or less, and the current surface density of the window foil member is 4.7 mA / mm ² or less. The electron beam irradiating device according to claim 6, wherein the driving current of the electron beam generating unit is set as described above. The thickness of the window foil member is 5 × 10 ^-3 mm.
The control unit sets the drive voltage of the electron beam generating unit so that the tube voltage of the electron beam generating unit is 130 kV or less, and the current surface density of the window foil member is 4.0 mA / mm ² or less. The electron beam irradiating device according to claim 7, wherein the driving current of the electron beam generating unit is set as described above. The electron beam generator that generates the electron beam and the electron beam generator
A housing portion provided with an opening for passing the electron beam generated from the electron beam generating portion, and a housing portion.
An electron beam irradiation window portion arranged in the opening portion and having a window foil member for transmitting the electron beam passing through the opening portion, and an electron beam irradiation window portion.
A method for manufacturing an electron beam irradiation device including a control unit for controlling the electron beam generation unit.
The first step of setting the range of the drive voltage of the electron beam generation unit by the control unit, and
The second step of specifying the area of the incident region of the electron beam in the window foil member, and
A third step of setting a range of drive current of the electron beam generating portion so that the current surface density in the window foil member is equal to or less than a predetermined limit current surface density based on the area of the incident region is provided. Manufacturing method of electron beam irradiation device. The second step includes a step of arranging a fluorescent member in place of the window foil member, a step of acquiring the area of a light emitting region that emits light due to the incident of the electron beam in the fluorescent member as the area of the incident region, and the above-mentioned step. The method for manufacturing an electron beam irradiating apparatus according to claim 9, further comprising a step of removing the fluorescent member and arranging the window foil member after obtaining the area of the light emitting region. A fourth step of preparing the window foil member having a thickness of 2 × 10 ^-3 mm or more and 1 × 10 ^{-2 mm or less is provided.}
In the third step, as the upper limit of the drive voltage range set in the first step becomes smaller for the window foil member of one type and the thickness, the upper limit of the drive current range is set. The method for manufacturing an electron beam irradiation device according to claim 9 or 10, which is set to be small. In the third step, a critical current surface density approximation value approximated by a quadratic function with the drive voltage of the electron beam generator as a variable, based on the drive voltage of the electron beam generator and the thickness of the window foil member. The method for manufacturing an electron beam irradiation device according to claim 11, wherein the drive current of the electron beam generating unit is set so as to be equal to or less than the calculated limit current surface density approximate value. In the third step, a critical current surface density approximation value approximated by a linear function with the thickness of the window foil member as a variable is obtained based on the drive voltage of the electron beam generating portion and the thickness of the window foil member. The method for manufacturing an electron beam irradiation device according to any one of claims 9 to 12, wherein the drive current of the electron beam generating unit is set so as to be calculated and equal to or less than the calculated critical current surface density approximate value. A fourth step of preparing the window foil member having a thickness of 3 × 10 ^-3 mm or more and 5 × 10 ^{-3 mm or less is provided.}
In the first step, the range of the drive voltage of the electron beam generating unit by the control unit is set so that the tube voltage of the electron beam generating unit is 130 kV or less.
The electron beam according to any one of claims 9 to 13, wherein in the third step, the range of the driving current is set so that the current surface density in the window foil member is 5.3 mA / mm ^{2 or less.} Manufacturing method of irradiation device. In the fourth step, the ^{window foil member having a thickness of 4 × 10 -3} mm or more and 5 × 10 ^-3 mm or less is prepared.
In the first step, the range of the drive voltage of the electron beam generating unit by the control unit is set so that the tube voltage of the electron beam generating unit is 130 kV or less.
The method for manufacturing an electron beam irradiation device according to claim 14, wherein in the third step, the range of the driving current is set so that the current surface density in the window foil member is 4.7 mA / mm ^{2 or less.} In the fourth step, the window foil member having ^{a thickness of 5 × 10 -3 mm is prepared.}
In the first step, the range of the drive voltage of the electron beam generating unit by the control unit is set so that the tube voltage of the electron beam generating unit is 130 kV or less.
The method for manufacturing an electron beam irradiation device according to claim 15, wherein in the third step, the range of the driving current is set so that the current surface density in the window foil member is 4.0 mA / mm ^{2 or less.}

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