JPS5963700A - Electrode structure for particle accelerator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrode structure that improves the acceleration performance of a culm and particle calorometer.

As shown in FIG. 1, the high-frequency acceleration cavity of the particle accelerator includes a cylindrical body 1 and an end plate 2 forming a vacuum vessel, and accelerating electrodes 3 are attached to the cylindrical body 1 at predetermined intervals. Particles such as electrons or positrons are incident from arrow A, accelerated by high frequency, and emitted from arrow B.

In the high frequency acceleration cavity of this particle accelerator, the attachment part of the accelerating electrode is required to have a structure with perfect electrical contact and low electrical contact resistance in order to improve acceleration performance. In other words, the Q value of the high frequency acceleration cavity is proportional to (energy stored in the west of the acceleration cavity)/(energy lost in the acceleration cavity),
If the electrical contact is incomplete, the acceleration performance will deteriorate.In addition, in an acceleration cavity that uses high-power, high-frequency waves, if the electrical contact is incomplete, problems such as local heat generation and discharge will occur at the contact portion.

Therefore, in order to obtain a high accelerating electric field at a given resonant frequency, the particle accelerator aligns the accelerating electrodes 3 with very high precision in terms of spacing, concentricity, inclination, etc. It's hanging. Furthermore, inside the accelerating cavity, there is a high-frequency wall loss as shown by the dashed line H in Fig. 2. As shown, an accelerating electrode stem 4 passing through the cylindrical body 1, a contactor 5 interposed between the stem 4 and the cylindrical body 1, and a gasket retainer 6
The inner surface of the cylindrical body 1 is provided with a gasket 7.8 for vacuum sealing the penetration part of the accelerating electrode stem 4, and a tightening nut 9 for tightening and fixing the accelerating electrode stem 4 to the cylindrical body 1. A copper plating layer of 1 m is provided on the surface of the electrode stem 4 and the surface of the contactor 5, respectively.

4a and 5a are provided. And these steel plating layers 1
m, 4m, , 5a reduce the electrical resistance when the high frequency current flows from the surface of the accelerating electrode stem 3 to the inner surface of the cylindrical body 1 via the contactor 5 as shown by arrow C.

At this time, the contactor 5 connecting the cylindrical body 1 and the accelerating electrode stem 4 is a factor that greatly influences the electrical performance of the accelerating cavity.
There is a contact surface pressure of This contact surface pressure is maintained between the copper plating layers 1a and 4 both during operation with a heat load and during stoppage.
It is not possible if a and 5a are merely in contact with each other; a strong contact surface pressure between the plating layers is required.

When initially assembling this high-frequency acceleration cavity, the accelerating electrode must be assembled with high precision. Therefore, this is done when the operation is stopped, when thermal expansion of each member due to thermal load does not occur. In this case, when the accelerating cavity assembled in this way is put into operation even if the tightening nut 9 is tightened to a predetermined tightening torque, the amount of heat generated by the cylindrical body 1 and the accelerating electrode stem 4 decreases due to the heat generated by the above-mentioned wall loss. Temperature differences occur due to differences in cooling effects, and differences in linear expansion coefficients occur due to differences in materials. However, each component constituting the electrode mounting portion has high rigidity and cannot absorb displacement. For this reason, the tightening thickness dimension d has expanded and shrunk, and as a result, the contact pressure of the upper and lower contact portions a and b of the contactor 5 has become excessive as shown in FIG.
Or, as shown in FIG. 5, there is a shortage. Fig. 6 shows the relationship between the contact surface pressure P and the deflection δ of the tightening thickness dimension d. Pl is the required contact surface pressure, but the contact pressure corresponding to the change Δδ of the tightening thickness dimension d is shown in FIG. The surface pressure change ΔP1 is large,
If the contact pressure of the upper and lower contact areas a and bi is too large, the copper burnt layer 1 will undergo thermal deformation, and if the thermal load is removed when the operation is stopped, the tightening thickness dimension d will decrease. becomes smaller. As a result, a volume of air is produced between the carp taffeta 5 and the cylindrical body 1, making it impossible to maintain a strong contact surface pressure.

Further, as shown in FIG. 5, when the cylindrical body 1 and the contactor 5 are in a non-contact state, the acceleration performance is significantly reduced. As a solution to this problem, it has been considered to increase the number of tightening nuts 9. However, when the supply is increased, the accelerating electrode 4 makes a planar rotational movement,
As the position of the accelerating electrode 4 changes, the resonance frequency goes out of order.
It cannot demonstrate its performance as an accelerating cavity. Furthermore, even if the feed rate is increased in the winter, if the machine stops again after operation, the contact surface pressure will be insufficient again, and it will be necessary to increase the feed rate each time the machine is started and stopped.

The purpose of this is to maintain a predetermined contact surface light in the high frequency path between the accelerating electrode and the cylindrical body both during operation and when stopped, and to increase the contact surface pressure of the contactor. The aim is to create a unipolar structure for a particle accelerator that can be increased without shifting its position.

In other words, the present invention includes an accelerating electrode stem penetrating the cylindrical body, a mud contactor interposed between the stem and the cylindrical body,
A gasket that is held down by a gasket holder and vacuum-seals the accelerating electrode stem penetration part, and an increase washer and a spring are installed between the gasket holder and the tightening nut in the electrode structure of the cylindrical accelerator, with the accelerating electrode stem being held through the gasket holder. This is a 22-knee valve with a washer interposed therein, and a bolt that presses the gasket presser against the washer toward the cylindrical body. i
t7+*-m□2゜m c-cmq.

FIG. 7 is a cross-sectional view showing the electrode structure of the particle accelerator.

In this electrode structure, an accelerating electrode stem 12 passes through a cylindrical body 11, and a contactor 13 is interposed between the cylindrical body 11 and the accelerating electrode stem 12 on the inner surface of the cylindrical body 11. Gaskets 14 and 15 for vacuum sealing are provided at the penetration portion of the accelerating electrode stem 12, and are pressed by a socket holder 16. A retightening washer 17 is installed on the top of the gasket holder 16.
is provided. This retightening washer 17 is provided with a rising part 17b around a disk part 17h having a through hole in the center. I am wearing 18.

This retightening bolt 18 has its lower end in contact with the gasket retainer 16. Further, a tightening nut 19 is attached to the upper end of the accelerating electrode stem 12, and a spring washer 20 is interposed between the tightening nut 19 and the disc portion 17 of the retightening washer 17.

Further, the inner surface of the cylindrical body 11, the surface of the accelerating electrode stem 12, and the surface of the contactor 13 are coated with a steel plating layer 1, respectively.
1m, 12&, 13% are formed.

Next, the operation of the electrode structure configured as described above will be explained.

After the contactor 13 is attached to the accelerating electrode stem 12 in a normal temperature state when the operation is stopped, the tightening nut 19 is tightened to a predetermined torque. This tightening force is transmitted to the cylindrical body 11 via the spring washer 20 and the retightening washer 17, and an initial contact surface pressure P is generated on the contact surface of the contactor 13. This initial contact surface pressure P.

As a result, the high frequency passage (contact portion of the contactor 13) between the accelerating electrode stem 12 and the cylindrical body 11 has the necessary contact surface pressure to obtain complete contact.

This state is shown in FIG. 8(a). In the figure, S is the spring constant of the contactor 13, S is the spring constant of the spring washer 20, and S3
represents the composite spring constant of S and S2. Note that the amount of axial deformation of the accelerating electrode stem 12, the amount of deformation of the screw portion of the tightening nut 19 and the retightening gel 18, and the amount of deformation of the retightening washer 17 are extremely small compared to the spring constants of the contactor 13 and the spring washer 20. Therefore, it can be ignored. As shown in FIG. 8(A), the spring constant of the contactor 13 is set to be functionally much larger than the spring constant of the spring washer 20. This is because if the spring constant of the contactor 13 is small, the axial displacement (spring deflection) is increased when the accelerating electrode is assembled, and the predetermined tightening force (contact surface pressure) is increased.
This is because the vertical positioning of the accelerating electrode stem '12 supported by the soft contactor 13 is hindered, leading to a decrease in performance.

□ In the condition shown in Figure 8 (a), after obtaining the specified contact surface pressure P1, do you tighten it again? The seat 18 is tightened to a predetermined torque, the gaskets 14 and 15 are compressed, and vacuum sealing is performed. Additional tightening? As the seat 18 is tightened, the retightening washer 17 rises, and the contactor 13 and spring washer 20 are further compressed. As a result, as shown in FIG. 8(b), the contactor 13 has a displacement δ1.
, a displacement δ occurs in the spring washer 20, and the contact surface pressure is P.

It changes from P to P.

However, when the operating state is entered in the levered state, displacement occurs due to the difference in heat generation amount between the cylindrical body 11 and the accelerating electrode stem 12, the temperature difference due to the difference in cooling effect, and the difference in linear expansion coefficient due to the difference in material.

Assuming that this displacement is ±Δδ as shown in FIG. 8(C), the contact surface pressure will be P2±ΔP. In this case, even if the contact surface pressure is small (P2-ΔP2), the necessary contact surface pressure can always be maintained as long as it is not less than 23. Also P2
Even if it becomes +ΔP2, since the ratio of ΔP2 to P is small, the contact surface pressure on both sides of the contactor 13 does not increase rapidly. Therefore, an excessive force d is not applied to plastically deform the copper plated layers 11a, '1c, and 13a.

As explained above, according to the present invention, a spring washer with a small spring constant is combined with a b-tanctor with a large spring constant to reduce the composite spring constant, and a retightening mechanism is added. Most of the splash can be absorbed by the washer, making it possible to maintain stable contact pressure at all times without significant changes in contact pressure. Furthermore, since retightening is performed using retightening bolts, retightening is possible without disturbing the centering accuracy of the accelerating electrode, which is a significant effect.

[Brief explanation of drawings]

Figure 1 is an overview of the acceleration cavity of a particle accelerator, Figure 2 is an explanatory diagram showing the state in which heat load is generated within the acceleration cavity, and Figure 3 is a conventional particle accelerator showing section D in Figure 1. Fig. 4 is an enlarged cross-sectional view of the electrode structure, Fig. 4 is a cross-sectional view showing a situation where the contact surface pressure of the contactor is too high in the same electrode structure, and Fig. 5 is a cross-sectional view showing the state where the contact pressure of the contactor is too small in the same electrode structure. Figure 6 is a diagram showing the relationship between deflection (δ) and contact pressure CP) in the same electrode structure. Figure 7 is a diagram showing the electrode height of a particle accelerator according to an embodiment of the present invention. Figure 8 (a) is a cross-sectional view of the same electrode structure, and a line diagram showing the relationship between the deflection (δ) and the contact surface pressure ψ) when tightening the tightening nut.
B) is a diagram showing the relationship between the deflection (contact surface pressure ψ) when tightening the retightening nut in the same electrode structure, and the figure G is a diagram showing the relationship between the deflection (δ) and the contact surface pressure during operation in the same electrode structure. Surface pressure (P) 11... Cylindrical part, 12... Accelerating electrode stem, 13... Contactor, 14.15... is slit, 16... f sket holder, 17... Retightening washer ,
77a... Disc part, 17b... Standing part, 18...
- Retightening bolt, 19... Tightening nut, 2o... Spring washer, 11a, 12a, 13*... Copper plating layer.

Claims (1)

[Claims] An accelerating electrode stem that penetrates the cylindrical body, a contactor interposed between the stem and the cylindrical body, a gasket that is held down by a gasket holder and vacuum-seals the part through which the accelerating electrode stem passes, and a gasket holder that holds the accelerating electrode stem in place. In the electrode structure of a particle accelerator, which is provided with a tightening nut that is tightened and fixed to the cylindrical body via a
A retightening washer and a spring washer are interposed, and the retightening washer is
Retightening by pressing the gasket holder in the direction of the cylindrical body? Electrode structure of a particle accelerator equipped with a bolt.