JPS62188149A - Radiation device - Google Patents

Abstract

PURPOSE:To obtain an X-ray generation device having no air leak part while having little local and timing change of temperature by getting rid of a vacuum sealed part surrounding an axis of rotation while spraying a cooling medium on a target to be cooled. CONSTITUTION:An electron gun 2 radiating electron rays is fixed to a vacuum wall 1 rotating by an external driving force. Thereby a vacuum sealed part causing air leak into a vacuum is removed. Electrons radiated from the electron gun 2 are downwardly deflected as shown by the arrows (a) and (b) due to a magnetic field vertically applied in the direction of electron radiation to be incident to a target 5. X-rays emitted from the target 5 are taken out outside an X-ray generator through a ring-shaped window 6 mounted on the vacuum wall 1. The target 5 to be heated by the electron radiation gets rid of heat by a cooling medium jetted from a nozzle 10. Thereby, a rate of temperature rise due to the electron ray radiation can be made smaller.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an irradiation device for charged particles such as an electron beam, which requires heat removal for local heating caused by irradiation.
This invention relates to an irradiation device suitable for application to a special KX-ray generator.

[Prior art]

Conventional irradiation equipment of this type, as described in Japanese Patent Application Laid-Open No. 51-57176, supplies a cooling medium to a target rotating in a vacuum by geoinding the target once and using a hollow rotating shaft supported by a bearing and a vacuum seal. A method was used in which the target was pumped into a hollow target (see Figure 3). However, it is technically difficult to vacuum-seal a rotating shaft that rotates at high speed and maintain a vacuum, and air leaks from the vacuum-sealed portion cause instability of the electron beam.

[Problem that the invention seeks to solve]

As mentioned above, the above-mentioned prior art basically has an unavoidable problem of air leakage from the vacuum seal surrounding the rotating shaft that rotates at high speed. For example, currently the leakage from the vacuum seal is ~10-@torrt/sec, but in this case,
Assuming that the volume t-1 inside the vacuum wall is the degree, the degree of vacuum decreases to 10-' torr in about 3 hours as shown in Figure 2, and the electron beam becomes unstable, so stable X-rays are obtained. things become difficult. Also, vacuum seals on shafts that rotate at high speed are sensitive to temperature changes.

Another problem is that it has a short lifespan (~2 years). Furthermore, in order to reduce local temperature changes in a target whose temperature rises rapidly when irradiated with an electron beam, it is necessary to increase the rotational speed of the target to flatten the temperature over time. However, the rotation speed of the rotating geoind part is 300'Or,p,
Since the limit is reached at about m, there is a problem that it cannot be done if it is necessary to extremely reduce one local temperature change (several 10 C).

An object of the present invention is to provide an X-ray generating device that has no air leakage portions and has little local temporal change in temperature.

[Means for solving problems]

The above object is achieved by eliminating the vacuum seal surrounding the rotating shaft and by not using a rotating geoind. 1st
The figure is a perspective view showing the basic configuration of the present invention, taking an X-ray generator as an example. FIG. 4 shows a cross section including the l-11 axis. By applying the present invention, vacuum maintenance can be ensured as shown by the dashed line in FIG. An X-ray generator shoots accelerated electrons into a target, and extracts bremsstrahlung X-rays and characteristic X-rays emitted from the target. As shown in FIG. 1, an electron gun 2 that emits an electron beam is fixed to a vacuum wall 1. The vacuum wall 1 is rotated by an external driving force. Therefore, the electron gun 2 also rotates together with the vacuum wall 1.

The electron gun 2 is composed of a filament 3 and an electrode 4, and an AC or DC voltage is applied to the filament 3 by a power source 8.

A DC voltage is applied to the electrode 4 by a power source 9.

Electrons are emitted from the filament 3 heated by the power source 8, and the electric field created by the electrode 4 causes the electrons to be emitted toward the target 5 in parallel to the central axis 1-If in FIG. on the other hand.

A magnetic or electric field is applied from outside the vacuum wall in a fixed direction. Figure 1 shows the case when a magnetic field is applied.

A magnetic field is applied perpendicularly to the direction of electron emission. Therefore, the electrons emitted from the electron gun 2 are caused by the magnetic field always being applied in a fixed direction independently of the rotation of the vacuum wall 1,
It is deflected downward as indicated by arrows a and b shown in the figure, and enters the target 5. Target 5 is a vacuum wall I with window 6 in between.
K is fixed and rotates concentrically with the vacuum wall 1. Released from target 5 e X', 1! is taken out to the outside of the X-ray generator through a ring-shaped window 6 attached to the vacuum wall l.

The window 6 is made of a material 1 having high X-ray transmittance, such as Be.

The X-rays transmitted through the window 6 enter a sample 7 or a spectroscopic device such as a diffraction grating (not shown). In the case of the present invention, when an external magnetic field is always applied in a fixed direction, the electrons are deflected in a fixed direction. Therefore, the X-ray generation position is always the same point with respect to the sample, independent of rotation, and X-rays of a constant intensity enter the sample from a constant direction. On the other hand, the heat of the target 5 heated by the electron irradiation is removed by the cooling medium injected from the nozzle 10.

[Effect]

Effects of the nine irradiation devices constructed as described above.

An overview of the effects and a comparison with conventional equipment will be given below.

In order to suppress local heating caused by electron beam irradiation, in conventional techniques, the target is usually rotated using a hollow rotating introduction terminal introduced from the outside.

In the present invention, as shown in FIG. 1, a target 5 is fixed to a vacuum wall 1 and rotated together with the vacuum wall 1, thereby eliminating a vacuum seal portion that causes air leakage into the vacuum. Therefore, by coating the inner surface of the vacuum wall 1 with a substance (for example, titanium) that has an adsorption effect on residual gas, the vacuum can be maintained and the lifespan of the device can be shortened due to instability of the electron beam and deterioration of the one-turn vacuum seal. This problem disappears. Further, unlike the conventional example, it is not always necessary to use rotational geoindication. For example, when the cooling medium is sprayed by the nozzle 10 as shown in FIG. 1, there are almost no factors that limit the number of revolutions as in the case of using a one-rotation geoind, so the temperature rise due to electron beam irradiation can be reduced.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. The vacuum wall 18 in this example is configured to be 100 am x 2100 a. A gear 19 for rotating the vacuum wall is fixed to a part of the vacuum wall 18. The motor 20 rotates the vacuum wall 18 by means of the ratio gear 21 and the gear 19 mentioned above.

The vacuum wall 18 is rotatably supported by a pair of support bearings 22. A permanent magnet 23 is installed around the vacuum wall 18 to form a magnetic field with a width of 30 am inside the vacuum wall 18.

For example, create a magnetic field of about o, oos tesla. And the distance from the electron gun 24 to the target 25 is 200f.
1 and the accelerating voltage is 50 kV, the electron beam will irradiate the target 25 in a circle with a diameter of 120 tttxz as the vacuum wall 18 rotates. target 25
The window 16 is made of copper or molybdenum or the like, and the target 25 is made of beryllium and has a width of about 3 to 5 m. Heat is removed by spraying a cooling medium (water) from a nozzle 26. The cooling medium that has absorbed heat is collected by a tray 27 and drained. Next, a method of supplying power to the electron gun 24 is shown in FIG. The power supply section is composed of an iron core 29 connected to the vacuum wall 28, a secondary coil 30 fixed to the iron core 29, and a primary coil 31 wound around the secondary coil 30.
9 and the secondary coil 30 rotate together with the vacuum wall, and the primary coil 31 is supported and fixed by a member not shown.

When alternating current is applied to the primary coil 31, a magnetic field is induced in the secondary coil 30, and a voltage is induced in the secondary coil.

Then, a current (
AC) flows and the filament 32 is heated. On the other hand, by connecting the light change induced in the secondary coil to the electrode 35 through the transformer 33 and the rectifier 34, an electrostatic field is formed within the vacuum wall 28. Therefore, the thermoelectrons emitted from the filament 32 by heating the filament 32 are transferred to the vacuum wall 2.
It is accelerated in the direction of the central axis by the electrostatic field within 8 and moves forward.

The method described above was to apply alternating current from the outside and use two coils to supply alternating current to the rotating body, but it is also possible to generate electricity using the driving force that rotates the vacuum wall and use it as a power source for a subgun. It is. This will be explained below using FIG. 7. Coil 39 directly connected to filament 36 and transformer 37° rectifier 38
rotates with the vacuum wall 40. Coil 39 is magnet 41
Since the coil 39 rotates within the coil 39, an alternating current is induced within the coil 39,
Similar to the embodiment of FIG. 5, the filament 36 in the electron gun is heated and the transformer 37. An electrostatic field is formed through the rectifier 38 to generate an electron beam.

Next, FIG. 8 shows an embodiment in which AC or DC voltage is directly supplied. A terminal 44 connected to the filament 42 of the electron gun and a terminal 45 connected to the electrode 43 are provided in a ring shape around the vacuum wall 46. Terminal 44 and terminal 45 above
, a brush 47 and a brush 48 connected to a DC power source are shown.
is conductive through sliding contact. Therefore, it is possible to supply power to the electron gun regardless of the rotation of the vacuum wall 46. in this case.

Although the need to improve the contact between the brush and the terminal is a technical issue, there is no need to rotate the power supply, so the device can be simplified.

Next, an embodiment of the target cooling method will be described with reference to FIG. FIG. 10 is a sectional view including the central axis (■--■). An inner flange-shaped guide 5 is provided around the target 49.
0, and after the cooling medium injected from the nozzle 51 collides with the target 49, it is driven to the periphery by centrifugal force and is sandwiched between the kite 50 and the target 49. As a result, the cooling medium is pressed against the region (around the target 490) where the temperature rises most rapidly due to electron beam irradiation, thereby improving heat removal efficiency.

As in the embodiment shown in Fig. 1, by eliminating the sliding seal part, the conventional problem of air leakage (leakage of atmospheric air) into the air is eliminated, and the configuration is free from one-turn geoindication. . Therefore, by simply coating the vacuum wall with a substance that has an adsorption effect such as titanium, the inside of the vacuum wall can be reduced by 10-'
It is possible to maintain a vacuum of about torr. 20000~30000r, since rotational geoind is not used.
It is now possible to rotate at high speeds p and m, and as shown in Figure 14, the temperature rise due to local heating of the target has been reduced to 1/3 to 1/3 of the conventional level.
It can be reduced to 1/4 and has the effect of extending the life of the target. It is easily understood from FIG. 14 that when the number of revolutions per rotation is increased, local temperature changes (changes over time) are reduced. When the present invention is applied, high-speed rotation is possible because there is no sliding seal part, and as a result, temperature uniformity can be obtained.

Furthermore, in the conventional X-ray generator, evaporated atoms from the filament of the electron gun adhere to the target (K), and some of the X-rays that should originally be generated from the target atoms are generated from the atoms attached to the target. Alternatively, there is a problem in that the spectrum and intensity of X-rays change due to scattering and absorption by attached atoms. In the present invention, electrons emitted from a filament are deflected by an electric field or a magnetic field on the way and are incident on a target. On the other hand, the evaporated atoms from the filament have an electric field,
Since the filament moves straight without being affected by the magnetic field, the evaporated atoms from the filament do not adhere to the target portion that is irradiated with the electron beam, as shown in FIG. Therefore, the disturbance 1 intensity change in the X-ray spectrum, which has been a problem in the past, does not occur in principle.

In each of the above-mentioned embodiments, the target can be rotated at high speed because no sliding seal portion is provided.

When high-speed rotation of the target is not required (for example, 3
000 rpm or less), it is also possible to supply the cooling medium using a one-turn joint. A modification using a rotating joint is shown in FIG. FIG. 12 is a sectional view including the central axis (■-■). target 52
The hollow shaft 53 connected to the rotary geoind 54 is connected to the rotary geoind 54, and has a structure in which a cooling medium can enter and exit the inside of the hollow shaft 53.

Although the embodiment shown in FIG. 4 described above has a configuration in which the electron beam is bent by a magnetic field, it is also possible to bend the electron beam by an electric field. FIG. 13 shows an example in which bending is performed using an electric field. The size of the vacuum wall 55 is the same as that of the embodiment shown in FIG.
56 electrodes are provided above and below. The electrode 56 has a distance of 120m between the electrodes.
+, electrode size 1100 m x 50 + voltage 'f-5 kV. In this example, if the accelerating voltage of the electron beam is 50 kV, the electrons will be incident on the circumference of the target 57 with a diameter of 68 m+.

〔Effect of the invention〕

As described in detail above, according to the irradiation device aK of the present invention, there is no sliding seal that may cause air to flow into the vacuum chamber, so air leakage can be completely prevented, and furthermore, air leakage can be prevented locally. It has an excellent practical effect of being able to suppress temperature changes (changes over time).

[Brief explanation of drawings]

FIG. 1 is a partially cutaway perspective view for explaining the basic configuration of an example of the irradiation device according to the present invention. FIG. 2 is a chart showing a comparison between the state of vacuum maintained in the prior art and the state of vacuum maintained when the present invention is applied. FIG. 3 is a sectional view of a known example. FIG. 4 is a sectional view taken along line I-II in FIG. 1. FIG. 5 is a partially cutaway perspective view of one embodiment of the present invention. FIGS. 6 to 8 are explanatory diagrams each showing an embodiment of the power supply portion. Figure 9 is an explanatory diagram of an example of the cooling means, and Figure 10 is its ■-
■It is a sectional view including the line. FIG. 11 is an explanatory diagram showing a modification of the present invention, and FIG. 12 is a cross-sectional view including the line v-■. FIG. 13 is a partially cutaway perspective view showing an embodiment different from the above. FIG. 14 is a chart showing the relationship between rotation speed and temperature. 1... Vacuum wall, 2... Electron gun, 3... Filament, 4... Electrode, 5... Target, 6... Window,
7...Sample, 8...Power supply, 9...Power supply, 10...
- Nozzle, 11... bulkhead. 12... Anticathode, 13... Fixed wing, 14... Seal. 15... Rotating joint, 16... Fixed conduit, 17
... Seal & 18... Vacuum wall, 19... Gear, 2
0...Motor, 21...Gear, 22...Bearing, 23...Magnet. 24...Electron gun, 25...Target, 26...
nozzle. 27... Receiver is plate, 28... Vacuum wall, 29... Iron core, 30... Secondary coil, 31... Primary coil, 32
... Filament, 33 ... Transformer, 34 ... Rectifier %35 ... Electrode, 36 ... Electrode, 37 ... Transformer, 38 ... Rectifier, 39 ... Coil, 40・・・
・Vacuum wall, 41... Magnet, 42... Filament,
43... Electrode, 44... Terminal, 45... Terminal, 4
6... Vacuum wall, 47... Brush, 48... Brush, 49... Target, 50... Guide, 51...
・Nozzle, 52...Target, 53...Hollow shaft,
54...Rotating geoind & 55...Vacuum wall, 56.
··electrode. 57...Target.

Claims (1)

[Scope of Claims] 1. In an irradiation device comprising a charged particle beam generating means, a target member to be irradiated with the charged particles, and a vacuum wall forming a vacuum chamber, the charged particle beam is directed against the vacuum wall. An irradiation device characterized in that the generation means is fixed, the target member is fixed to the vacuum wall, and the mutually fixed components are rotatably supported and rotationally driven means are provided. . 2. The irradiation device according to claim 1, wherein the irradiation device is provided with means for generating at least one of an electric field and a magnetic field in order to deflect the charged particle beam. Device. 3. Claims characterized in that the target member constitutes a part of a vacuum chamber and is configured to be forcedly cooled by supplying a cooling fluid from the atmospheric side thereof. The irradiation device according to item 1. 4. Claims characterized in that the target member has an inner flange-shaped portion formed on its atmosphere side, and this inner flange-shaped portion is arranged concentrically with respect to the rotation axis of the vacuum chamber. The irradiation device according to item 3. 5. The target member is a combination of hollow double structure tubes, the hollow double structure tubes are arranged concentrically with the rotation axis of the target member, and the double structure tubes are arranged concentrically with the rotation axis of the target member. 3. The irradiation device according to claim 2, wherein the irradiation device is configured such that the cooling fluid can be supplied through the irradiation device. 6. The irradiation device according to claim 2, wherein the vacuum wall is partially made of a material that can transmit X-rays. 7. The irradiation device according to claim 6, wherein the X-ray transparent portion is provided along a circumference perpendicular to the rotation axis of the vacuum wall. 8. The vacuum wall shall have a secondary coil fixed concentrically to its rotation axis, and shall face the secondary coil,
A primary coil is disposed at a distance, the primary coil is fixedly supported on the stationary member, and the primary coil is fixedly supported on the stationary member.
3. The irradiation device according to claim 2, wherein the secondary coil is connected to charged particle generating means. 9. The above-mentioned vacuum wall has a generator coil fixed thereon,
Further, a magnetic field generating means is disposed facing and spaced apart from the generator coil, and the magnetic field generating means is fixedly supported on a stationary member. The irradiation device according to item 2. 10. The irradiation device according to claim 2, wherein the vacuum wall is provided with a slip ring-shaped terminal along a surface perpendicular to the rotation axis thereof.