JPH0728716Y2 - Charged particle accelerator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is used in, for example, an ion implantation apparatus, an electron beam irradiation apparatus, etc., and is a charged particle accelerator for accelerating charged particles such as ions and electrons. Regarding

[Conventional technology]

 FIG. 2 shows a conventional example of this type of charged particle accelerator.

This device includes, for example, several tens to several tens of centimeters of the accelerating tube 4 composed of an insulating cylinder 6, an accelerating electrode 8, a fixed potential electrode 10, a voltage dividing resistor 12 and the like, and between both ends of the accelerating tube 4 via wires 20a and 20b. An accelerating power supply 14 for applying a DC high voltage of about several hundred KV is provided. For example, charged particles 2 such as ions generated in the high potential part 16a are accelerated through the accelerating tube 4 to the ground potential part 16a.
I am trying to lead to b.

Since the path of the charged particles 2 needs to be maintained in vacuum, the pipes (generally made of metal) 18a, 18b are usually provided between the acceleration tube 4 and the high potential part 16a and the ground potential part 16b as in this example. Connected by each.

[Problems to be solved by the device]

In the accelerating tube 4 as described above, discharge may occur due to the reason that the charged particles 2 hit the structure or the like.

For example, a discharge 32 may occur between the accelerating electrode 8 and the pipe 18b, and at that time, a surge current i due to the discharge 32 flows toward the earth side 14e of the accelerating power supply 14, but the path has conventionally passed through the wiring 20b. There were more than just things.

That is, although a control system such as the control unit 24 is usually mounted on the ground potential section 16b, the pipe 18b is indicated by reference numeral 2 in the drawing.
As shown in 2, it is electrically connected to the chassis of the control unit 24, the ground, etc. through a structure such as a pedestal in the ground potential part 16b, and the ground terminal 26 of the control unit 24 is connected by a ground wire 28b. It is connected to a reference potential point on the ground side, that is, the ground side 14e of the acceleration power supply 14 in this example.

Therefore, the path of the surge current i is not limited to the path passing through the wiring 20b, but the electrical connection 22 and the ground wire 28 by the structure.
When the surge current i flows through such a ground line of the control system, a potential difference is generated between the respective parts, which adversely affects the control system including the control unit 24, such as malfunction or failure. There was a problem of causing.

Such a problem is that a control system is mounted on the high potential part 16a, and it is connected to the ground side 28a (however, this line is not grounded to the ground. The same applies hereinafter), that is, the reference potential point on the plus side, that is, this reference potential point. In the example, the same may occur when the positive side 14p of the acceleration power source 14 is connected.

So, even if a discharge occurs in the acceleration tube,
It is an object of the present invention to provide a charged particle accelerator in which the surge current does not flow into other circuits such as the earth line of the control system.

[Means for Solving the Problems]

The charged particle accelerating device of the present invention inserts a metal pipe electrically insulated from the structure between at least one end of the accelerating tube and the structure having the same potential as the structure described above, Moreover, the metal pipe is connected to the polarity side of the above-mentioned acceleration power source into which the metal pipe is inserted by a dedicated wiring.

[Action]

According to the above structure, when a discharge is generated in the acceleration tube,
The surge current flows exclusively to the acceleration power supply through the metal pipe and the dedicated wiring, and does not flow to other circuits such as the earth line of the control system. Therefore, the surge current does not adversely affect other circuits such as the control system.

〔Example〕

FIG. 1 is a schematic diagram showing a charged particle accelerator according to an embodiment of the present invention. The same or corresponding parts as those in the example of FIG. 2 are designated by the same reference numerals, and the differences from the conventional example will be mainly described below.

In this embodiment, between the both ends of the accelerating tube 4 as described above and the pipes 18a and 18b as described above, which are one of the structures at the same electric potential, respectively, and an insulating ring 34a from them. And 34b electrically insulate the metal pipes 36a and 36b, respectively.

Then, the two metal pipes 36a and 36b are connected to the reference potential point on the plus side and the reference potential point on the ground side, that is, the plus side 14p and the ground side 14e of the acceleration power source 14, respectively by dedicated wirings 38a and 38b. .

According to the above configuration, when the discharge 32 is generated in the acceleration tube 4, the surge current i thereof may be insulated from the metal pipe 36b and the pipe 18b by the insulating ring 34b when focusing on the ground side, for example. It flows exclusively to the earth side 14e of the acceleration power supply 14 through the metal pipe 36b and the dedicated wiring 38b, and the electrical connection by the structure of the control system as in the conventional case 22
And, it does not flow to the route on the side of the ground wire 28b.

As a result, in the control system including the control unit 24, the surge current i does not flow in the earth line, although the whole electric potential may rise and fall due to the above-mentioned discharge, so that there is no potential difference on the earth line. Therefore, it is possible to prevent the control system from being adversely affected by the surge current i and causing malfunction or failure.

The above is the same for the plus side,
Since the surge current i flows exclusively through the dedicated wiring 38a and does not flow toward the ground line 28a, the control system mounted on the high potential portion 16a is not adversely affected.

Further, with the above arrangement, the surge current i can be limited by inserting an inductance or a resistance in series with one or both of the wirings 38a and 38b to increase the impedance. By the way, in the conventional example, the wiring 20a, 20b
If the impedance of the path is increased, a large amount of surge current i flows through the ground line of the control system, and the adverse effect on the control system becomes greater.

If the pipes 18a, 18b are not used, the metal pipes 36a, 36b
May be connected to required structures of the high potential portion 16a and the ground potential portion 16b via the insulating rings 34a and 34b.

If there is no control system or the like on the high potential portion 16a side or the ground potential portion 16b side that is particularly damaged by the surge current i as described above, that side of the accelerating tube 4 is not necessarily the same as this embodiment. In addition, the structure as in the conventional example may be used.

Further, in each of the above examples, the case where the accelerating electrode 8 uses the single-stage accelerating tube 4 is illustrated, but the same applies when the accelerating electrode 8 uses the multi-stage accelerating tube.

[Effect of device]

As described above, according to the present invention, even if discharge occurs in the acceleration tube, the surge current flows exclusively through the metal pipe and the dedicated wiring described above, and does not flow into other circuits such as the earth line of the control system. . Therefore, the surge current does not adversely affect other circuits such as the control system.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a charged particle accelerator according to an embodiment of the present invention. FIG. 2 is a schematic diagram showing an example of a conventional charged particle accelerator. 2 ... charged particles, 4 ... acceleration tube, 14 ... acceleration power supply, 18a, 18b ...
Piping, 34a, 34b ... Insulation ring, 36a, 36b ... Metal piping, 38a,
38b ... Dedicated wiring.

Claims (1)

[Scope of utility model registration request] 1. A charged particle accelerator comprising an accelerating tube for accelerating charged particles and an accelerating power source for applying a DC voltage to the accelerating tube, wherein at least one end of the accelerating tube and a structure having the same potential as that of the accelerating tube. A metal pipe electrically insulated from the structure is inserted between the structure and the metal pipe, and the metal pipe is connected to the polarity side of the acceleration power supply into which the metal pipe is inserted by a dedicated wiring. Charged particle accelerator.