JPH1040844A - High-voltage proof undischarged pair electrodes - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of gas discharge due to high-voltage application, by forming glass lining layers respectively on the insulator nipping surfaces of a pair of electrodes for facedly nipping an insulator, in a high voltage proof undischarged pair electrodes for accelerating charged particles in a vacuum. SOLUTION: High-voltage proof discharge pair electrodes 1 for accelerating charged particles in vacuum consists of electrodes 12 and 13 facing with each other, and an insulator 16 nipped between these electrodes 12 and 13. At this time, glass lining layers 14 and 15 are formed on the surfaces of the electrodes 12 and 13 so as to eliminate a gap between the electrodes 12 and 13 and the insulator 16. Moreover, a sodium lime glass is used for the glass lining layers 14 and 15, and alumina is used for the insulator 16. Consequently, the occurrence of gas discharge can be suppressed, even if high voltage is applied to the electrodes 12 and 13, thereby preventing the deterioration of electrode material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high withstand voltage non-discharge counter electrode, and more particularly to a charged particle generator for an electron beam, an ion beam, etc., a charged particle accelerator, an electron microscope, a microwave tube, and the like. The present invention relates to a high-breakdown-voltage non-discharge counter electrode suitable for the present invention.

[0002]

2. Description of the Related Art Conventionally, in charged particle generators for electron beams, ion beams, etc., charged particle accelerators, electron microscopes, microwave tubes, etc., a high withstand voltage has been used to accelerate charged particles in a vacuum. A non-discharge counter electrode is used. FIG. 8 is a schematic sectional view of a conventional electron beam generator, and FIG. 9 is a perspective view showing its appearance. As shown in FIGS. 8 and 9, this electron beam generator has a cylindrical vacuum chamber 3.
0, a minus electrode 32 provided on the top surface of the vacuum chamber 30, and a donut-shaped plus electrode 33 having a hole 33 a at the center provided at the top of the cylindrical portion of the vacuum chamber 30. . In the middle of the cylindrical portion of the vacuum chamber 30, a non-discharge counter electrode 31 is mounted. The non-discharge counter electrode 31 is used as an acceleration electrode. The non-discharge counter electrode 31 includes two donut-shaped metal electrodes 34 and 35 facing each other, and these metal electrodes 3
4 and 35, and a donut-shaped insulator 36 sandwiched between them. A vacuum pump 38 is connected to an exhaust port 37 at a lower portion of the vacuum chamber 30.

In this electron beam generator, a vacuum pump 3
After the inside of the vacuum chamber 30 is made high vacuum by 8, a DC voltage is applied between the minus electrode 32 and the plus electrode 33. Electrons jump out of the negative electrode 32, and a part thereof passes through the hole 33 a of the positive electrode 33. The electrons passing through the holes 33a are accelerated by the electric field generated by the non-discharge counter electrode 31. The speed of the accelerated electrons depends on the magnitude of the voltage applied to the metal electrodes 34 and 35 of the non-discharge counter electrode 31, and the higher the applied voltage, the faster the electrons can be extracted.

However, the non-discharge counter electrode 31 has a structure shown in FIG.
As shown in FIG. 7, since a gap 39 exists between the metal electrode 34 or 35 and the insulator 36, when a high voltage is applied between the metal electrodes 34 and 35, the gap 39 is formed. May cause gas discharge. Due to such gas discharge, the materials of both the metal electrode 34 or 35 and the insulator 36 are deteriorated, and the inside of the vacuum chamber 30 is contaminated. Further, a loss of electric power occurs, and sometimes the electron beam generator itself is damaged.

When the gap 39 exists, moisture, organic components, and the like are released from the electrode surface through the gap 39 into the vacuum chamber 30 as a gas. The released gas causes the electron beam to not fly properly, contaminates the vacuum chamber 30, lowers the degree of vacuum, and the like.

[0006]

As a countermeasure against such a gas discharge phenomenon, the dimensional accuracy and the smoothness of the contact surface between the metal electrode 34 or 35 and the insulator 36 are increased to make the gap 39 as small as possible. . However, no matter how the dimensional accuracy and the smoothness are improved, the gap 39 still exists, so that this measure cannot be said to be sufficient. Also,
Although measures have been taken to make the electrodes 34 and 35 and the insulator 36 into a shape in which discharge is unlikely to occur, this is not sufficient. In addition, there is a measure to metallize the surface of the insulator 36 to make it conductive, but the durability of the metallized layer is poor and it is not a complete measure.

The present invention has been made in view of such problems of the prior art, and an object of the present invention is to provide a high breakdown voltage non-discharge counter electrode which does not generate gas discharge even when a high voltage is applied. It is to be.

[0008]

The high withstand voltage non-discharge counter electrode of the present invention comprises a glass lining layer formed on at least the opposing surfaces of the opposing counter electrodes so that an air layer is directly formed on the surface of the electrodes. Is to avoid contact. Thereby, the voltage at which gas discharge starts to be generated can be increased. Further, even if gas discharge occurs, the electrode material is not deteriorated because the electrode surface is covered with the glass lining layer.

Also, by making the material of the insulator and the material of the glass lining layer substantially the same, their dielectric constants become equal, the potential gradient between the two electrodes becomes uniform, and the gas discharge is reduced. Generation is suppressed.

Further, if the glass lining layer and the insulator are fused to each other, there is no gap between the glass lining layer and the insulating layer, and the generation of gas discharge is further suppressed. The phenomenon that moisture and organic components adsorbed or occluded on the material surface of the part are released by baking in a vacuum is suppressed.

[0011]

Embodiments of the present invention will be described below. The high breakdown voltage non-discharge counter electrode of the present invention is used in a vacuum in charged particle generators for electron beams, ion beams, etc., charged particle accelerators, electron microscopes, microwave tubes, and the like. And two insulators, and an insulator sandwiched between these electrodes. A glass lining layer is formed on the surface of these electrodes. The glass lining layer only needs to be formed on at least the surfaces facing each other, that is, the surfaces sandwiching the insulator. As the insulator, silicon nitride ceramics, alumina porcelain, quartz glass, soda-lime glass, borosilicate glass, or the like is used. By forming the lining layer, there is no gap on the surface of the electrode, and the voltage value at which gas discharge starts to be generated can be increased.

In one embodiment of the present invention, the material of the insulator can be the same as the material of the glass lining layer.
Usually, the material of the glass lining layer is almost the same as that of soda-lime glass, so that soda-lime glass can be used for the insulator. If the material of the insulator and the material of the glass lining layer are substantially the same, their dielectric constants are equal, the potential gradient between the two electrodes can be made uniform, and the occurrence of gas discharge is suppressed. be able to.

Furthermore, if the glass lining layer and the insulator are fused to each other, there is no gap between the glass lining layer of the two electrodes and the insulator, and the occurrence of gas discharge can be further suppressed. it can. Further, the phenomenon that moisture and organic components adsorbed or occluded on the material surface in the gap portion are released by baking in vacuum is also suppressed.

[0014]

FIG. 1 shows a sample 1 for testing the performance of an embodiment of a high breakdown voltage non-discharge counter electrode of the present invention in which a glass lining layer is formed on the surface of an electrode. The sample 1 of the present embodiment has two electrodes 12 and 13 facing each other, and the surfaces of these electrodes 12 and 13 are subjected to glass lining processing.
4 and 15 are formed. Glass lining layer 14,
No. 15 has almost the same composition as soda-lime glass.
Electrodes 12, 1 on which glass lining layers 14, 15 are formed
Between them, an insulator 16 made of alumina is sandwiched. The sample 1 is subjected to a withstand voltage test described below in a state where the electrodes 12 and 13 and the insulator 16 are pressed by using an appropriate jig.

FIG. 2 shows a sample 2 for testing the performance of another embodiment of the high breakdown voltage non-discharge counter electrode of the present invention. The sample 2 of this embodiment is the same as the sample 1 of FIG. 1 except that the electrodes 12, 13 and the insulator 16 are tightly fixed by screws 18, 18, and corresponding elements have the same reference numerals. Is attached.

FIG. 3 shows a sample 3 for testing the performance of still another embodiment of the high breakdown voltage non-discharge counter electrode of the present invention. In the sample 3 of the present embodiment, the insulator 16 is formed of the glass lining layer 1 formed on the surfaces of the electrodes 12 and 13.
The insulator 16 and the glass lining layers 14 and 15 are integrally formed by fusing soda lime glass having a composition substantially similar to that of the soda lime glass. The sample 3 can be manufactured using a jig 17 as shown in FIG.
That is, the fixing plate 19 is held at a predetermined distance by the fixing bolt 18, and the fixing plate 19 is attached to the glass lining layer 1.
The electrode 12 on which the electrode 4 is formed, the electrode 13 on which the glass lining layer 15 is formed, and the insulator 16 sandwiched therebetween are fixed by bolts 20, 20. After fixing in this manner, the sample 3 was placed in a furnace, heated and fused at a temperature similar to that in the case of the glass lining processing, that is, 800 ° C. for 1 hour, and cooled in the furnace to obtain Sample 3 of this example. Was.

FIG. 4 shows a sample 4 of a comparative example for testing the performance of a conventional high breakdown voltage non-discharge counter electrode for comparison. In the sample 4, the glass lining layer was not formed on the surfaces of the electrodes 12 and 13, and the electrode 1
Screws 18 with the insulators 16 in direct contact with the insulators 2 and 13
18 and closely fixed.

Using the above-mentioned samples 1 to 4, the degree of vacuum is set to 10
^A withstand voltage test was performed at ^-5 Torr. FIG. 6 shows the result. In the figure, the voltage applied between the two electrodes 12 and 13 is gradually increased, and the voltage at which gas discharge occurs is plotted. The vertical axis indicates the voltage (kV), and the horizontal axis indicates the number of discharges. .

As shown in FIG. 1, the withstand voltage of sample 4 of the comparative example having no glass lining layer is as low as about 50 kV. The withstand voltage is low because fine irregularities are present on the surfaces of the electrodes 12 and 13, and gas discharge occurs between the irregularities and the insulator 16. The tendency that the withstand voltage increases as the number of discharges increases is seen.
It is presumed that this is because the fine asperities existing on the surfaces of the electrodes 12 and 13 are destroyed by the electric discharge and are flattened.

On the other hand, in the sample 1 of the embodiment, the initial discharge voltage is high, and the discharge voltage tends to further increase as the number of discharges increases. The reason why the discharge voltage is so high is that
This is probably because the glass lining layers 14 and 15 are interposed between the electrodes 12 and 13 and the insulator 16.
The reason why the withstand voltage tends to increase as the number of discharges increases is presumed to be because the discharge suppresses the volatilization of the adsorbed or occluded substances present on the surface of the glass lining layer in the gap. You.

The sample 2 of Example 2 had a high initial discharge voltage, which was at a practical level. However, there was a tendency that the discharge voltage gradually decreased as the number of discharges increased. This is presumably because in the sample 2, a complicated structural portion such as the screw portion 18 is exposed, and thus gas release and gas discharge from this portion have an effect.

Further, in the sample 3 of the embodiment, the initial discharge voltage is much higher than those of the samples 1, 2 and 4. This is because there is no gap between the electrode 12, the glass lining layer 14, the insulator 16, the glass lining layer 15, and the electrode 13.

FIG. 7 shows an electron beam generator manufactured by the same structure as the sample 1 of FIG. 1, and this electron beam generator has a non-discharge counter electrode 21. The non-discharge counter electrode 21 is provided with two donut-shaped electrodes 22 and 23 facing each other, and the surfaces of these electrodes 22 and 23 are glass-lined by a glass lining process.
25 are formed. Glass lining layers 24, 25
A doughnut-shaped insulator 26 is sandwiched between the electrodes 22 and 23 having the above-mentioned structure. Other elements are the same as those in FIG. 8 for explaining the related art, and corresponding elements are denoted by the same reference numerals. Although only one non-discharge counter electrode 21 is shown in FIG. 7, in order to increase the speed of the obtained electrons, one or a plurality of the same counter electrodes 21 are further placed below the counter electrode 21 with an insulator interposed therebetween. May be connected. In the electron beam generator of the present embodiment, a high voltage could be applied to the counter electrode 21 and a high-speed electron beam could be obtained.

[0024]

According to the non-discharge counter electrode of the present invention, since a glass lining layer is formed on opposite surfaces of two electrodes to which a high voltage is applied, generation of gas discharge is suppressed and gas discharge is suppressed. Even if a high voltage is applied until discharge occurs, deterioration of the electrode material is hardly observed.

Further, by making the material of the insulator the same as the material of the glass lining layer, their dielectric constants become equal and the potential gradient between the two electrodes is made uniform to suppress the generation of gas discharge. Can be.

Further, in the configuration in which the glass lining layer and the insulator are fused together, there is no gap between the two electrodes to which a high voltage is applied, the glass lining layer on the surface of these electrodes, and the insulator. Therefore, the generation of gas discharge can be further suppressed, and the volatilization of moisture and organic components adsorbed or occluded on the material surface in the gap can be suppressed.

Accordingly, the high breakdown voltage non-discharge counter electrode of the present invention is
For example, charged particle generators such as electron beams and ion beams,
When used in a charged particle accelerator, an electron microscope, a microwave tube, or the like, high-speed accelerated particles can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a sample for testing the performance of an example of a high breakdown voltage non-discharge counter electrode of the present invention in which a glass lining layer is formed on the surface of an electrode.

FIG. 2 is a sectional view showing a sample for testing the performance of another embodiment of the high breakdown voltage non-discharge counter electrode of the present invention.

FIG. 3 is a cross-sectional view showing a sample for testing the performance of still another embodiment of the high breakdown voltage non-discharge counter electrode of the present invention.

FIG. 4 is a cross-sectional view showing a sample of a comparative example for testing the performance of a conventional high breakdown voltage non-discharge counter electrode for comparison.

FIG. 5 is a side view showing a method for manufacturing the sample of FIG.

FIG. 6 is a diagram showing the results of a withstand voltage test performed on the samples of FIGS.

FIG. 7 is a sectional view showing an electron beam generator manufactured by the configuration of FIG.

FIG. 8 is a schematic sectional view of a conventional electron beam generator.

FIG. 9 is a perspective view showing an appearance of the conventional electron beam generator of FIG.

FIG. 10 is a cross-sectional view showing a portion where gas discharge occurs in a conventional non-discharge counter electrode.

[Explanation of symbols]

 1,2,3,4 sample 12,13 electrode 14,15 glass lining layer 16 insulator 21 non-discharge counter electrode

Claims (3)

[Claims] A high-breakdown-voltage non-discharge counter electrode used in a vacuum, comprising two electrodes facing each other and an insulator sandwiched between the electrodes, wherein the two electrodes have at least one another. A high-breakdown-voltage non-discharge counter electrode, wherein a glass lining layer is formed on each of the surfaces facing each other and sandwiching the insulator. 2. The high-breakdown-voltage non-discharge counter electrode according to claim 1, wherein the material of the insulator is the same as the material of the glass lining layer. 3. The high breakdown voltage non-discharge counter electrode according to claim 1, wherein the glass lining layer and the insulator are fused to each other.