JP3401278B2 - Ion accelerator - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ion accelerator. 2. Description of the Related Art FIGS. 2 to 4 show a conventional ion accelerator, but a high-voltage terminal 2 made of a substantially rectangular metal is not shown in FIG. It has a built-in mass separation magnet, which is supported on the floor by insulating columns. The entire ion accelerator is covered with a shield box 1, and a high voltage generator 3 and a power supply 14 are provided between one side surface of the high voltage terminal 2 and the inner wall of the shield box 1 facing the high voltage terminal 2.
Bushings 9 and 17 made of insulating material are attached. The high-voltage generator 3 is configured in a known manner, and a casing 3a containing the high-voltage generator is fixed to the outer surface of the shield box 1, and includes an AC power supply 5
Is supplied as an input, and a high-frequency output from the controller 4 is supplied via a cable 6. As shown in FIG. 3, a voltage doubler circuit 12 including a diode 31 and a capacitor 32 is built in the casing 3 a, and a DC high voltage, for example, an output of 400 KV from the voltage doubler circuit 12 is supplied to the high voltage terminal 2 via the conductor 21. It is being supplied. The conductor 21 is covered with an insulating material, for example, FRP, and this is a so-called bushing 9.
Are mounted at a predetermined pitch, and a resistor 8 is connected between the metal hoops 7. [0003] A casing 14a containing a power generation unit of the power supply device 14 is also fixed to the outer wall surface of the shield box 1, and as shown in FIG. , A primary winding 34 is wound, and AC UV as a ground potential is supplied to the input terminal 13. The secondary winding 35 passes through the metal tube 20, and the output terminal 18 is in the high voltage terminal 2. The metal tube 20 is covered with a bushing 17 made of an insulating material, and a metal hoop 15 electrically connected by a resistor 16 similar to the resistor 8 at a predetermined pitch as shown in FIG. It is installed. FIG. 4 shows details of a bushing portion of the high-voltage generating device 3. Each metal hoop 7 has an inner, that is, a small-diameter annular metal body 7b, and an outer, that is, a larger-diameter annular metal body. 7a and an annular flat plate portion 7c made of a thin metal connecting these annular metal bodies 7a and 7b, and these metal hoops 7 are FRP (insulating material) between them.
And a collar 40 consisting of
1 is inserted, and nuts 4 are provided at the upper and lower ends thereof.
The cross section welded to the thin plate portion 7c of the uppermost metal hoop 7 is fixed to the bushing 9 by means of an L-shaped tightening band 50. The bushing of the power supply device 14 and the metal hoop 15 are configured in the same manner, and the output terminal 18 of the insulating transformer 11 is connected to a terminal block 24 via a noise filter 23. It is configured to supply power to a mass separation magnet and the like. Although not shown, a known accelerating tube is mounted between one side surface of the high-voltage terminal 2 and the inner wall of the shield box 1 facing the same, and the related mechanism is the same as the conventional one. The conventional ion accelerator is constructed as described above, but the length of the bushings 9 , 17 is 80c.
m and 400 KV class, which is short, the potential difference between the metal hoops becomes large. Therefore, due to the strong electric field between these hoops, a leakage current flows on the insulating surfaces of the bushings 9 and 17 and the surface of this insulating material The charge builds up, thus disrupting the potential on this surface, causing the electric field to be non-uniform and increasing the probability of inducing a discharge. Moreover, even if it discharges once, the bushing 9 , 1
The electric charge induced on the surface of No. 7 remains, and even if the voltage is increased again, the electric charge is discharged without reaching the originally generated voltage. The more such a discharge is repeated, the more the bush
The withstand voltage of the rings 9 and 17 is reduced. SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide an ion accelerator capable of increasing the withstand voltage of a bushing without increasing its length. With the goal. Means for Solving the Problems At least an ion source and
And a casing with a built-in mass separation magnet
At the same height, and the case
A predetermined high voltage is applied to the
Power is supplied to the on-source and mass separation magnet, etc.
A shield box for electromagnetically shielding the casing
Is provided, and one side of the casing is opposed to the one side.
Between the inner wall surface of the shield box and
Between the power supply and the floor,
Accelerating the predetermined high voltage to the casing and at least
It overturned the conductive member for applying to the pipe, made of an insulating material
First bushing and deriving power of the power supply device
Bushing made of insulating material covering conductive member for
And the first bushing and the second bushing are provided.
Check whether the potential of the casing is
Multiple ring metal bodies to divide
In the ion accelerator attached with
Of the body and the outer peripheral surface of the first bushing and the second bushing
An annular conductive rubber member is sandwiched between at least one
An ion accelerator characterized in that: The electric charge generated on the surface of the bushing through the annular member made of conductive rubber flows to the metal annular body and can be led to the ground potential through each resistor. Can prevent the surface from being charged up, thereby preventing the electric field from becoming non-uniform. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an ion accelerator according to an embodiment of the present invention will be described with reference to FIG. The same reference numerals are given to the portions corresponding to FIGS. 2 to 4 of the conventional example,
Detailed description is omitted. [0010] Metal hoop 1 of conventional power supply device 14
5 and the bushing 17 are connected to the high voltage generator 3.
In the present embodiment, the gap S is filled with the annular conductive rubber member 60. That is, the inner diameter of the annular conductive rubber member 60 in the natural state is slightly smaller than the outer diameter of the bushing 17, and the inner diameter of the hoop 15 b inside the metal hoop 15 is smaller than the outer diameter of the annular rubber member 60 attached as shown in the figure. The inside diameter is slightly smaller. Thus, the annular conductive rubber member 60 is connected to the outer surface of the bushing 17 and the metal hoop 15.
Between the hoop 15b and the inner hoop 15b by rubber elasticity. The ion accelerator according to the embodiment of the present invention is configured as described above. Next, this operation will be described. The metal hoop 15 is also connected to the high voltage generator 3 shown in FIG.
The configuration is the same as that of the metal hoop 7. That is, the outer hoop 15a and the inner hoop 15b are connected by the thin flat plate 15c, but are schematically shown in the drawing. In FIG. 1, a high voltage of 400 KV generated by a high voltage generator 3 is applied to a high voltage terminal 2. The output terminal 18 of the power supply 14 arranged adjacent to the high-voltage generator 3 is also placed at the same potential as the high-voltage terminal 2. Therefore, in the power supply device 14, a high voltage of 400 KV is applied to the metal tube 20. For this reason, a strong electric field is generated between the metal hoops 15, which charges the surface of the bushing 17 with electric charges. When the leakage current due to this reaches the conductive rubber ring 60,
The leakage current flows through the internal hoop of the metal hoop 15 through the resistors 16 mounted on each stage to the ground potential. As described above, charge-up of the surface of the bushing 17 is prevented, and thus, non-uniformity of the electric field can be prevented, and thus discharge can be prevented. Although the embodiment of the present invention has been described above, the present invention is, of course, not limited to this, and various modifications can be made based on the technical idea of the present invention. For example, in the above embodiment, the power supply device 1
The conductive rubber ring 60 is sandwiched between the bushing 17 of FIG. 4 and the bushing 9 of the high voltage generator 3 adjacent to the bushing 17. The rubber ring may be pinched. Further, in the above embodiment, the exhaust pipe for keeping the devices in the accelerating pipe and the high voltage terminal under reduced pressure has not been described. However, this also relates to the high voltage terminal 2 and the inner wall of the shield box 1. May be provided adjacent to the high voltage generator 3 and the power supply device 14, and a metal hoop similar to that of the embodiment is provided on the outer peripheral portion of the bushing. Then, a similar conductive rubber member may be sandwiched. Further, in the above embodiment, the high voltage generator 3 and the power supply 14 are provided with one side of the high voltage terminal 2 and
It was mounted between the inner wall of the shield box 1 and the opposite, but instead was installed below the high voltage terminal 2 and was installed on the outer peripheral surface of the bushing of the high voltage generator and the power supply. A conductive rubber ring may be sandwiched between the metal hoop and the bushing. Further, a high voltage generator and a power supply device are arranged on the side of the high voltage terminal, and a metal hoop is provided on an outer peripheral surface of the bushing between the high voltage and power supply portion and the ground surface derived from the upper end. Also in the ion accelerator, a conductive rubber ring may be sandwiched between the metal hoop and the bushing. As described above, according to the ion accelerator of the present invention, the bushing has a length of 80 at 400 KV class.
Even when the bushing has a size of about cm, the surface of the bushing is prevented from being charged with electric charge, thereby preventing discharge from occurring. That is, the withstand voltage can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially broken plan view of a main part of an ion accelerator according to an embodiment of the present invention. FIG. 2 is a partially broken plan view of a conventional ion accelerator. FIG. 3 is a sectional view of the same. FIG. 4 is a partially broken plan view showing details of a metal hoop mounting structure in a conventional example. [Explanation of Signs] 60 Conductive Rubber Ring

Claims (1)

(57) Claims 1. A casing containing at least an ion source and a mass separation magnet is disposed at a predetermined height from the ground, and a predetermined high voltage is applied to the casing by a high voltage power supply device. was applied, so as to supply electric power such as the ion source and mass separation magnet by the power supply device is provided with electromagnetically shielded to shield box said casing, said Ke
And the shield facing the one side
Between the inner wall of the box or the casing and floor
And the predetermined high voltage of the high voltage power supply device.
Applying pressure to said casing and at least to the accelerating tube
Bushing made of insulating material, covering a conductive member for
And a conductive member for deriving power of the power supply device
And a second bushing made of an insulating material is provided.
On the outer peripheral surfaces of the first bushing and the second bushing, respectively.
In the ion accelerator, in which a plurality of annular metal members are attached to divide the potential of the casing from the ground potential with a gap therebetween, each of the annular metal members and the first bus are provided.
An ion accelerator characterized in that an annular conductive rubber member is sandwiched between at least one of the outer peripheral surfaces of the bushing and the second bushing .