JPH03102800A - High frequency multi-pole wire type accelerator - Google Patents

Abstract

PURPOSE:To lessen the dia. of a tank by furnishing magnetic material insulated from electrodes in an acceleration cavity, and thereby enlarging the inductance of the acceleration cavity. CONSTITUTION:Between electrodes 2a-2d magnetic material 3a-3d such as ferrite is installed on the inner surface of an acceleration cavity (tank) 1 in the same length as each electrode 2a-2d. Insulative sheets 4a-4h are inserted between the magnetic material 3a-3d and electrodes 2a-2d, and thereby the magnetic material 3a-3d is insulated from the electrode 2a-2d. Thereby the inductance increases while the resonance frequency decreases-in other words, the dia. of tank 1 required to obtain the same resonance frequency becomes smaller.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a high frequency multipole linear accelerator used, for example, as an injector of a large accelerator.

Conventional technology> Generally speaking, in high-frequency multipole linear accelerators, the method shown in Fig. 2 (
a) and b) Taking a conventional high-frequency quadrupole linear accelerator as an example, as shown in the perspective view and enlarged longitudinal cross-sectional view of the acceleration cavity, a cylindrical tank 21 with plates 21a and 21b attached at both ends is installed. , a plurality of electrodes 22a to 22d (
Each electrode 2 has a structure in which a
A waveform along the axial direction of the tank 21 is formed at the tips 2a to 22d.

Then, by introducing high-frequency power into the tank 21, the tank 21 is made to resonate, and the shape of the tips of the electrodes 22a to 22d creates the necessary acceleration and convergence electric field in the space surrounded by these, and the electric field is guided there. Accelerate charged particles.

In such a linear accelerator, the convergence force and bore radius r0 are determined by the particles to be accelerated, the incident energy, the output energy, etc., and from these, the resonant frequency f0 of the linear accelerator and the inter-vane capacitance C are determined.
. is determined.

From this f0 and 00, the inductance L0 required by the acceleration cavity is (2πro) 2=1/C. It is determined by L0, and L0 is 1/1 of the tank 21.
4 between the cross-sectional area S and the vacuum permeability μ. Then, L0=μ. There is a relationship: S, and from this, the tank diameter R that achieves the required S is determined.

Problems to be Solved by the Invention> By the way, in this type of linear accelerator, generally when trying to achieve a large focusing force, f0 becomes small, but the bore radius r0 is not made too small due to the discharge between the electrodes, the beam diameter, etc. As a result, the inter-vane capacitance C0 does not become very large.

As a result, L0 and therefore 31, that is, the tank diameter R, becomes large. If R becomes large, there will be disadvantages in terms of installation space, device weight, assembly accuracy, etc.

This invention was made in view of these points, and it is a high-frequency multipole that can realize the necessary resonant frequency without increasing the tank diameter R compared to the conventional one under the same acceleration conditions such as input and output energy. The purpose is to provide linear accelerators.

Means for Solving the Problems> In order to achieve the above object, in the present invention, as shown in FIG. 1 corresponding to the embodiment, inside the cavity (tank) 1,
The magnetic material 3a~ is kept insulated from each electrode 2a~2d.
3d is installed.

Effect> If the 1/4 cross-sectional area of the tank 1 is 31, the area occupied by the magnetic material is 32, and the remaining area is 31, then the magnetic materials 3a to 31 are
If the magnetic permeability (relative magnetic permeability) of 3d is μ, the inductance L0 of the cavity is Lo”poSt0μ.μr s z.Since μ, >>l, 1 to obtain the same L.
/4 cross-sectional area S (=S.+s!) becomes smaller.

<Example> FIG. 1 is a central vertical sectional view of an embodiment of the present invention.

In this embodiment, the basic structure of the tank 1, electrodes 2a to 2d, etc. is the same as the conventional structure shown in FIG.

In this embodiment, magnetic materials 3a to 3d such as ferrite are uniformly arranged along the inner surface of the tank 1 between the electrodes 2a to 2d, and have a length equal to that of each of the electrodes 2a to 2d. Insulating sheets 4a-4h are inserted between the magnetic materials 3a-3d and the electrodes 2a-2d, respectively, so that the magnetic materials 3a-3d are insulated from the electrodes 2a-2d.

The cross-sectional area of each magnetic material 3a to 3d in the radial direction of the tank 1 is St, which is equal to each other, and the 1/4 cross-sectional area S
The remaining area of each is SI.

In addition, cooling pipes 5 and 5 are provided in each of the magnetic materials 3a to 3d.
... 5 is passed through the pipe, and a refrigerant such as water can be flowed inside the pipe.

According to the above embodiments of the present invention, the inductance L0 is
Vacuum permeability is ゜μ. , when the relative magnetic permeability of the magnetic materials 3a to 3d is μ, Lo=μoS+ten#o#rSz (1).

By the way, magnetic materials 3a to 3d with the same 1/4 cross-sectional area S
As mentioned above, the inductance L0 in the case where there is no inductance L0 is LO=μaS (2), and S=St+Sz,μ,〉1. Therefore, the present invention can be implemented even if tanks with the same radius are used. In the example, the inductance L0 is larger,
The resonance frequency f0 becomes lower. In other words, according to the embodiment of the present invention, the tank diameter required to obtain the same resonance frequency f0 is reduced.

Here, in the embodiment of the present invention, when the device is driven, the magnetic materials 3a to 3d generate heat due to loss due to magnetic resistance, but this heat is released by passing a coolant through the cooling pipes 5...5. be able to.

Note that as the magnetic material provided in the tank 1, it is of course possible to use any material other than ferrite, but if an electrically insulating magnetic material is used, the insulation sheet 4a~
4h becomes unnecessary.

Further, the shape of the magnetic material is not limited to the above-mentioned embodiments, but is arbitrary, as long as it is inserted into the tank 1.

Furthermore, the present invention is not limited to quadrupole but can be widely applied to other multipole high frequency linear accelerators.

Effects of the Invention> As explained above, according to the present invention, by providing a magnetic material insulated from each electrode in the acceleration cavity of a multipole high-frequency linear accelerator, the inductance of the acceleration cavity can be increased. As a result, the tank diameter can be made smaller than in the past for use under the same conditions.

As a result, the device is smaller than the conventional device, which is advantageous in terms of installation space, device weight, and assembly accuracy.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of an embodiment of the present invention, and FIG. 2 is a structural explanatory diagram of a conventional quadrupole high frequency linear accelerator. 1...Tank 2a-2d...Electrode 3a-3d...Magnetic material 4a-4h...Insulation sheet 5...5...Cooling pipe

Claims (1)

[Claims] In a linear accelerator in which high frequency power is introduced into a cavity in which a plurality of electrodes are arranged, the cavity is caused to resonate and an accelerating electric field is formed in a space surrounded by the tips of the plurality of electrodes. A high-frequency multipolar linear accelerator characterized in that a magnetic material is disposed inside the accelerator while maintaining insulation from each of the electrodes.