JP2641565B2 - Quadrupole particle accelerator and device using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to quadrupole particles [hereinafter referred to as RFQ (Radio Frequency Q).
The present invention relates to an accelerator and a device to which the accelerator is applied, and more particularly to a quadrupole particle accelerator capable of simultaneously accelerating a plurality of beams and performing beam acceleration of a large current which has not been achieved conventionally.

[Conventional technology]

FIG. 4 shows the structure of a conventional RFQ accelerator. In the accelerator shown in the figure, the facing surfaces of the quadrupole electrodes 1, 2, 3, 4 are wavy, and an electric field is applied in the axial direction by applying a high-frequency voltage to these electrodes 1, 2, 3, 4. Is generated, and the charged particles that are incident are accelerated by the electric field.

By the way, when trying to accelerate a high-current ion beam, one RFQ limits the beam current that can be accelerated. This is because the amount of charged particles that can pass through a certain cross-sectional area is limited because the accelerated charged particles repel each other (action of space charge). Therefore, if the beam cross-sectional area of the RFQ is increased, it is possible to accelerate a high-current ion beam with a single RFQ.In this case, however, the pitch of the waving should be increased to maintain the axial acceleration effect. Must be done and the accelerating tube will be lengthened accordingly.

Against this background, the conventional RFQ structure for accelerating a large current beam is based on the IEE Transaction on New Clear Science, N.C.
S-32 (1985) pp. 3347-3349 [IEEE Tran
s. on Nucl Sci., NS-32 (1985) PP3347-3349], simply by arranging a plurality of RFQ rods and accelerating a plurality of beams simultaneously, the beam current of the ampere class as a total is obtained. Is obtained.

[Problems to be solved by the invention]

The prior art is excellent in that a plurality of beams are simultaneously accelerated to obtain an ampere-class high-current beam, but no consideration is given to reducing the size of the entire apparatus.

SUMMARY OF THE INVENTION An object of the present invention is to provide a quadrupole particle accelerator capable of obtaining a beam current larger than that obtainable by the above-described prior art method within a practical size by keeping the size of the entire apparatus small.

[Means for solving the problem]

The above purpose is not to form a wavy structure only in one direction with respect to the RFQ electrode, but to process the electrode so as to have a wavy structure in various directions, and to share one electrode, several This is achieved by forming a quadrupole electrode structure.

The present invention is also applied to a neutral particle injector for obtaining a neutral particle beam by neutralizing outgoing ions and a composite ion beam apparatus for accelerating a different ion beam.

[Operation] By forming a wavy structure in various directions with respect to the RFQ electrode, one electrode can be shared by a maximum of four quadrupole electrode sets. This eliminates the need to use many electrode rods as in the conventional method,
The device can be made compact.

〔Example〕

 Hereinafter, the present invention will be described based on embodiments of the drawings.

First, an embodiment in which two beams are accelerated will be described with reference to FIG. As shown in the figure, the lower quadrupole electrodes 1, 2, 3,
Electrode 1 of 4 is also shared with the upper quadrupole electrode,
2 ', 3', 4 'also form another quadrupole electrode set. The wavy structure of the electrode 1 is formed on the upper surface and the lower surface. Thus, although eight electrodes were conventionally required to accelerate two beams, the present embodiment can perform seven electrodes. Further, since the distance between the quadrupole electrode sets, which is conventionally required, is practically zero, the number of electrodes can be reduced and the size of the entire apparatus can be significantly reduced.

FIG. 2 shows an embodiment in which four beams are further accelerated. This figure shows a cross-sectional view of the electrode rod, and the symbols in the figure show the polarity of the potential. A high-frequency voltage is applied to the quadrupole electrode, but when two electrodes facing one another are located, the remaining two electrodes facing each other become. In addition,
The case where two beams are accelerated by the remaining seven electrodes except for the electrodes 5 and 6 corresponds to the embodiment of FIG. From the figure, it can be seen that the number of beams can be increased from two to four simply by adding two electrodes 5 and 6. In this case, since the conventional method requires four electrodes for each beam,
A total of 16 electrodes were required to accelerate the four beam bundles. On the other hand, in the present embodiment, the same performance can be obtained with nine electrodes, and in this embodiment, more electrodes can be reduced as compared with the case of the two beam accelerations.
The size of the device can be significantly reduced.

The effect of reducing the number of electrodes is further increased by increasing the number of acceleration beams. For example, to get an ampere beam
In the case of accelerating 12 beams at the same time, if electrodes are formed by extending FIG. 2, only 21 electrodes are required, and the number of electrodes is less than half that of the conventional method. Accordingly, the size of the device can be reduced to less than half.

Further, in FIG. 2, different ions can be simultaneously accelerated for each quadrupole electrode set by arbitrarily selecting the respective waving shapes for the four beams. At this time, since the voltage generated between the electrodes has the same value for all the electrodes, it goes without saying that simultaneous acceleration of different ions can be performed by adjusting the distance between the electrodes, the waving pitch, and the like.

Another embodiment is shown in FIG. This figure corresponds to 9 in FIG.
In this configuration, six voltage correction electrodes 11 are arranged outside the acceleration electrode rods. Since the actual voltage generated by each electrode rod is determined by the impedance of each electrode rod as viewed from the high-frequency power supply 12, voltage variation between the electrodes occurs depending on the wiring structure to each electrode. In order to correct this, by arranging the voltage correction electrode 11 which does not substantially contribute to the beam acceleration as shown in FIG. 3, the generated voltage of the electrode which directly contributes to the acceleration can be made uniform. According to the present embodiment, as the number of acceleration beams increases, there is an effect of suppressing the variation in the voltage generated between the electrodes.

The electrode material in each of the above-described embodiments is preferably copper, aluminum, and molybdenum and tungsten, which are easily processed, and are high-melting metals.

Further, the quadrupole particle accelerator described in each of the above embodiments is applied to a neutral particle injector for neutralizing ions to obtain a beam of neutral particles, or a composite ion beam device for accelerating heterogeneous ion beams. Thereby, the entire device can be downsized.

〔The invention's effect〕

According to the present invention described above, since the number of electrodes can be reduced when accelerating a plurality of beams with the RFQ accelerator, particles can be efficiently accelerated with small dimensions, and in particular, an ampere class It is effective when obtaining an accelerated beam of light ions. Such an ampere-class acceleration beam is required when applied to a high-speed neutral particle injector used for plasma heating, and the present invention is most effective at this time.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an electrode portion in a quadrupole particle accelerator according to one embodiment of the present invention, FIGS. 2 and 3 are schematic views each showing another embodiment of the present invention, and FIG. Traditional RFQ
It is a perspective view which shows the structure of the accelerator partially broken. 1,2,3,4,2 ', 3', 4'5,6 ... electrode rod, 10 ... acceleration tube.

Claims (6)

(57) [Claims] 1. A quadrupole particle accelerator for arranging four electrodes whose facing surfaces are waved to accelerate an ion beam, wherein at least one of the electrodes is oriented in the opposite direction. A surface other than the undulating surface also has a wavy structure, and a surface different from the wavy surface forms a part of a quadrupole electrode structure different from the quadrupole. Quadrupole particle accelerator. 2. The quadrupole particle accelerator according to claim 1, wherein another wavy shape formed on said electrode has a shape different from the original wavy shape. 3. The quadrupole particle accelerator according to claim 1, wherein an electrode that does not contribute to acceleration is arranged in addition to said electrode in order to eliminate a variation in generated voltage at each of said electrodes. 4. The quadrupole particle accelerator according to claim 1, wherein the waving shape is determined so that the generated voltages of the electrodes become equal. 5. The quadrupole electrode, wherein at least one electrode has a wavy structure on a surface other than the facing surfaces, and another surface different from the wavy surface is connected to the quadrupole. Is a neutral particle injector characterized in that a beam of neutral particles is obtained by neutralizing ions emitted from a quadrupole particle accelerator which forms a part of another quadrupole electrode structure. 6. The quadrupole electrode, wherein at least one electrode has a wavy structure on a surface other than the facing surfaces, and another surface different from the wavy surface is formed with the quadrupole. Is a composite ion beam apparatus that forms a part of another quadrupole electrode structure and accelerates a different ion beam using a quadrupole particle accelerator different from the original surface shape.