JP2583692B2 - Accelerator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an accelerator for accelerating charged particles by microwaves.

[0002]

2. Description of the Related Art FIG. 5A is a cross-sectional view showing a part of a conventional standing wave accelerator, and FIG. 5B is a schematic view of the accelerator. In the figure, 1 is an accelerating cavity, 2
Is a combined cavity, 3A to 3D are short rods 4A to 4 respectively.
D is a coupling cavity with a short bar.

[0003] The charged particles incident on the accelerating tube are accelerated cavities 1
The particles are accelerated by the high-frequency electric field between them and are output as high-energy particles. Here, for example, the combined cavity 3A
When the short rod 4A is inserted into the cavity, the microwave does not propagate through the coupling cavity 3A, but propagates only through the other acceleration cavity 4B. When the other short rods 4B to 4D are inserted, the coupling coefficient in the coupling cavity changes, and the state of the electric field changes.

For example, when the short rods 4A and 4C are inserted and the microwave propagates through the coupling cavities 3B and 3D, an electric field pattern as shown in FIG. When the short rods 4A and 4D are inserted and the microwave propagates through the coupling cavities 3B and 3D, the electric field pattern becomes as shown in FIG. When a wave propagates through the coupling cavities 4A and 4D, an electric field pattern as shown in FIG. 6C is obtained. When the short rods 4B and 4D are inserted and the microwave propagates through the coupling cavities 4A and 4C, FIG.
An electric field pattern as shown in FIG.

As described above, the energy (output energy) of the output charged particles can be switched by variously switching the electric field pattern in the accelerator tube. In addition,
Hereinafter, one short bar and the corresponding coupling cavity are referred to as an energy switching mechanism.

[0006]

The conventional standing accelerator has the following construction. Therefore, when a variety of output energies are required, a large number of energy switching mechanisms must be provided. However, there are problems that the configuration is complicated and adjustment is troublesome.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide an accelerator capable of obtaining various types of output energy using a smaller number of energy switching mechanisms.

[0008]

According to a first aspect of the present invention, there is provided an acceleration device, wherein one of a number of coupling cavities is a coupling cavity with a short rod, and further, the output energy in the microwave frequency characteristic is output. A variable frequency supply means for supplying a microwave having a frequency corresponding to a portion where the change in energy is small is provided.

According to a second aspect of the present invention, there is provided an accelerator according to the present invention, wherein a plurality of coupling cavities are coupled cavities with short rods, and further, a change in output energy in the output energy microwave frequency characteristic. Is provided with a variable frequency supply means for supplying a microwave having a frequency corresponding to a small portion.

[0010]

The variable frequency supply means according to the present invention outputs a microwave having a frequency determined based on the relationship between the output energy and the microwave frequency when the short bar is inserted.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 1 denotes an accelerating cavity of a standing wave accelerating tube;
Is a coupled cavity of a standing wave accelerating tube, 3 is a coupled cavity with a short rod provided with a short rod 4, and 5 is a stationary cavity composed of an acceleration cavity 1, a coupled cavity 2, and a coupled cavity 3 with a short rod. The wave accelerating tube 6 is a variable frequency supply means such as a klystron capable of outputting microwaves of various frequencies.

Next, the operation will be described. FIG. 2A shows an electric field pattern when the short bar 4 is not inserted.
(B) shows the electric field pattern when the short bar 4 is inserted. That is, there are two types of electric field patterns that can occur in this case. However, the charged particles accelerated from input to the standing wave accelerator tube 5 to the point where the coupled cavity 3 with the short rod reaches a certain point, when passing through the region where the electric field is 0 and thereafter, In addition, since energy is given to the accelerating cavity 1, the energy of the charged particles decreases.

The relationship (Vf curve) between the output energy and the microwave frequency when the short bar 4 is not inserted is:
For example, as shown in FIG. Usually, the frequency of the microwave used for acceleration is the frequency at which the change in V is the smallest with respect to the change in f in the Vf curve, that is, f ₀ in the example shown in FIG. .

Here, when the short bar 4 is inserted, V-
In the f-curve, for example, as shown in FIG. 3B, the output energy is reduced as a whole. However, in the area where the electric field does not exist, that is, after the point where the short rod 4 is inserted, the charged particles are not shown in FIG.
(C), the will undergo deceleration energy having an energy distribution around the resonance frequency f ₁ of the acceleration cavity 1.

Therefore, actually, the Vf curve is shown in FIG.
As shown in FIG. Here, with respect to the change of f, V
At three points (frequency f ₂ , f
_3, at the f ₄₎ there. Therefore, when the frequency of the microwave is set to one of f ₂ , f ₃ , and f ₄ when the short bar 4 is inserted, stable acceleration of the charged particles becomes possible. In other words, using one energy adjustment mechanism and four types of microwave frequencies f ₀ , f ₂ , f ₃ , f ₄ ,
Four types of stable output energy V ₀ , V ₃ , V ₄ , V
You can get ₅ .

Therefore, when it is desired to obtain the output energy V ₀ , the short rod 4 is pulled out, and the output frequency of the variable frequency supply means 6 such as a variable frequency klystron is set to f
_Set to ₀ . Further, when the output energy desired to be either V ₃ ~V _5, insert the short rod 4, the output frequency of the variable frequency supply means 6 and either of f ₂ ~f _4.

In the above embodiment, the case where one energy adjusting mechanism is provided to obtain 3 + 1 = 4 types of output energy has been described. However, as shown in FIG. 4, two short rods 41 and 42 are provided. Is also good. In this case, when the short rods 41 and 42 are not inserted, and when the short rod 41 is inserted into the coupling cavity 31 with the short rod, there are three types.
In addition, three types of charged particles having a total of seven types of output energy when the short rod 42 is inserted into the coupling cavity 32 with a short rod can be taken out. If three short rods are provided, charged particles having 3 × 3 + 1 = 10 types of output energy can be extracted.

[0018]

As described above, according to the present invention, the accelerator is provided with one or a plurality of coupled cavities with short rods in the standing wave accelerating tube, and V is most stable in the Vf curve. Since the configuration is such that microwaves having the same frequency are used, there is an effect that a device capable of extracting charged particles having different types of output energy can be obtained with a smaller energy adjusting mechanism.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an acceleration device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an electric field pattern in the acceleration tube shown in FIG.

FIG. 3 is a characteristic diagram showing an example of output energy microwave frequency characteristics.

FIG. 4 is a configuration diagram showing an acceleration device according to another embodiment of the present invention.

FIG. 5 is a sectional view and a schematic view showing a conventional standing wave accelerator.

6 is an explanatory diagram showing an electric field pattern in the accelerator tube shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Acceleration cavity 2 Combined cavity 3, 31, 32 Combined cavity with short bar 4 Short bar 5 Standing wave type acceleration tube 6 Variable frequency supply means

Claims (2)

(57) [Claims] 1. An accelerating device using a standing wave accelerating tube having a number of accelerating cavities and coupled cavities for accelerating charged particles by microwaves, wherein one of the coupled cavities is provided with a short bar. An acceleration device comprising a coupling cavity and variable frequency supply means for supplying the microwave having a frequency corresponding to a portion where the change in output energy in the output energy frequency characteristic is small. 2. An accelerating device using a standing wave type accelerating tube having a number of accelerating cavities and coupled cavities and accelerating charged particles by microwaves, wherein a plurality of the coupled cavities are short-circuited. An accelerating device comprising: a coupling cavity with a rod; and variable frequency supply means for supplying the microwave having a frequency corresponding to a portion where output energy change in output energy frequency characteristics is small.