JPH08213197A - Acceleration method for charged beam and linear accelerator - Google Patents

Abstract

PURPOSE: To provide a charged beam of high quality by accelerating a charged beam stably. CONSTITUTION: A linear accelerator is used, and a high frequency feed means 15 is provided in each of a pre-chamber 12, a chamber section 13 and a regular section 14 (hereinafter collectively referred to as 'each acceleration cavity'), thereby generating a high-frequency electrical field. At the same time, a charged beam source 11 and each high frequency feed means 15 are independently fitted with a timing adjustment means 17, and each means 17 is connected to a reference pulse generation means 16. According to this construction, the high-frequency electrical field is applied to a charged beam in such a condition as free from the effect of induced electrical field, and preferably on timing to stabilize the high-frequency electrical field in each acceleration cavity. A charged beam of high quality with uniform energy is thereby supplied.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charged beam accelerating technique and a charged beam linear accelerator which can be preferably used in a free electron laser.

[0002]

2. Description of the Related Art A linear accelerator is an apparatus for accelerating a charged beam by supplying a microwave to an accelerating cavity to generate a high frequency electric field, usually using a high frequency supplying means such as a klystron. The structure of a conventional general linear accelerator is shown in FIG. The pulsed charged beam emitted from the charged beam source 21 is velocity-modulated by a pre-buncher 22 which is a single acceleration cavity, and is accelerating after being clustered and accelerated by the acceleration cavity forming the buncher section 23. Acceleration is performed in the acceleration cavities that form the regular portion 24 whose phase velocity is the light velocity. In the conventional linear accelerator, the high frequency of the same frequency is supplied to the pre-buncher 22, the buncher section 23, and the regular section 2 by using a single high frequency supply means.
4 (Hereinafter, the above three parts are collectively referred to as each acceleration cavity)
Were being supplied at the same time. However, when high frequencies are simultaneously supplied, a time difference occurs in the decay of the induced electric field effect generated by the charged beam in each acceleration cavity. For this reason, the timing at which the charged beam can be stably accelerated varies depending on each acceleration cavity. Also, there is a difference in the time until the high-frequency electric field generated in each acceleration cavity becomes stable. Both of these impeded stable acceleration of the charged beam.

[0003]

SUMMARY OF THE INVENTION The present invention provides a linear accelerator composed of a plurality of accelerating cavities having different high frequency characteristics.
Acceleration of a charged beam that adjusts the timing when the induced electric field effect decays and the timing when the high frequency electric field becomes stable, efficiently accelerates the charged beam by the stable high frequency electric field, and supplies a high quality charged beam with uniform energy. An object is to provide a method and a linear accelerator.

[0004]

In order to solve the above-mentioned problems, the present inventor has provided a pre-buncher 12 and a buncher unit 1 with a pulsed charged beam emitted from a charged beam source 11.
3 and the regular section 14 are sequentially passed through to accelerate, and a high-frequency supplying means is used for each of the pre-buncher 12, the buncher section 13 and the regular section 14 (hereinafter, the three sections are collectively referred to as acceleration cavities). 15 is mounted to generate a high frequency electric field in each acceleration cavity, and a timing adjusting means 17 is attached to each of the charged beam source 11 and each high frequency supplying means 15, and each timing adjusting means 17 is used as a reference pulse generating means 16. It is characterized by accelerating the charged beam by adjusting the timing of emitting a pulsed charged beam and the timing of generating a high frequency electric field in each acceleration cavity based on the induced electric field effect generated in each acceleration cavity. A method of accelerating a charged beam is provided.

In the above charged beam accelerating method, the timing of emitting the pulsed charged beam and the timing of generating a high frequency electric field in each accelerating cavity are determined by the induced electric field effect generated in each accelerating cavity and further by each accelerating cavity. It is preferable to make adjustments based on the high-frequency characteristics of 1) to obtain a higher quality charged beam. In the linear accelerator in which the pulsed charged beam emitted from the charged beam source 11 sequentially passes through the pre-buncher 12, the buncher unit 13, and the regular unit 14, the high frequency supply means 15 is provided.
Are individually attached to the respective acceleration cavities, and the timing adjusting means 17 includes the charged beam source 11 and the respective high frequency supplying means 15.
Are individually attached to the reference pulse generating means 16
It can be easily solved by using a linear accelerator characterized by being connected to.

Here, the induced electric field effect generated in the acceleration cavity means that an induced electric field is generated when the charged beam enters and leaves the acceleration cavity. The high frequency characteristics of the acceleration cavity include, for example, the resonance frequency of the acceleration cavity, the shunt impedance, and the damping parameter.

[0007]

The present invention will be described in detail with reference to the drawings. 1 is a schematic diagram showing a configuration of a linear accelerator according to the present invention, FIG. 2 is a schematic diagram showing a configuration of a conventional linear accelerator, and FIG. 3 is a diagram showing disappearance and occurrence of an induced electric field effect,
It is a time chart which shows the relationship with application of a high frequency electric field.

In the present invention, the timing for applying the high frequency electric field to the pulsed charged beam is 1
The timing of emitting the charged beam and the high-frequency electric field are set so that the induced electric field effect caused by one pulse entering the accelerating cavity disappears until the induced electric field effect caused by the pulse leaving the accelerating cavity occurs. Adjust the timing to generate. This is to prevent disturbance of the high frequency electric field due to the induced electric field effect and to stably accelerate the charged beam. The timing of applying the high frequency electric field to the charged beam without receiving the induced electric field effect depends on the material of the acceleration cavity,
It depends on various factors such as the intensity of the charged beam and the structure of the accelerator. However, the timing can be adjusted to an appropriate timing by using, for example, experimental means, based on the induced electric field effect generated in each acceleration cavity. Specifically, the timing adjusting means 17 is used to change the emission timing of the charged beam and the generation timing of the high frequency electric field, and the change of the electric field in the acceleration cavity and the change of the charged beam are observed on the monitor screen through the antenna. However, there is a method of obtaining an appropriate timing of the release or generation.

Further, it takes a certain time (hereinafter referred to as a time constant τ) after the microwave is supplied to the acceleration cavity until the high frequency electric field for accelerating the charged beam becomes stable. The time constant τ depends on the high frequency characteristics of the acceleration cavity. Since the high-frequency characteristics of the acceleration cavities are different from each other, for example, when microwaves are simultaneously supplied to the acceleration cavities, the time until the high-frequency electric field becomes stable in the acceleration cavities varies. Therefore, in addition to the induced electric field effect, it is preferable to adjust the timing of emission and generation based on the high frequency characteristics of each acceleration cavity. Specifically, there is a method of adjusting the timing so as not to receive the induced electric field effect after the high-frequency electric field becomes stable in all the acceleration cavities. Whether or not the high frequency electric field of each accelerating cavity has become stable can be determined, for example, by observing the high frequency electric field on the monitor screen through the antenna as in the above.

Next, in the linear accelerator according to the present invention, the high frequency supplying means 15 is individually provided in the pre-buncher 12, the buncher portion 13 and the regular portion 14. Each high-frequency supply unit 15 can supply high-frequency electric fields of different frequencies as well as the same frequency to each acceleration cavity. The design performance of each accelerating cavity is exhibited, and it becomes easy to obtain a high-quality charged beam. The frequency of each accelerating cavity is determined according to each high-frequency supplying means 15. Further, the timing adjusting means 17 is individually attached to the charged beam source 11 and each high frequency supplying means 15, and each timing adjusting means 17 is connected to the reference pulse generating means 16. The reference pulse generating means 16 is a timing adjusting means 17.
Generates a pulse signal that serves as the reference of. Each timing adjusting means 17 supplies clock signals with different frequencies,
It can be generated at any timing.
The charged beam source 11 and each high frequency supplying means 15 operate in synchronization with the clock signal. By using the timing adjusting means 17 (for example, T047123 0611 manufactured by Pulse Electronics Co., Ltd.), it is possible to output the output pulses of the five channels by 1 μs each and 1 ms later than the reference pulse.

[0011]

In the high frequency linear accelerator according to the present invention, the pre-buncher, the buncher section and the regular section are provided with high frequency supplying means 15, respectively, and the charged beam source 11 and the high frequency supplying means 15 are connected to the timing adjusting means 17. This makes it possible to individually adjust the timing of emitting the charged beam and the timing of supplying the high frequency electric field. A high-quality charged beam can be obtained by adjusting the timing of emitting the charged beam and the timing of supplying the high-frequency electric field so that the high-frequency electric field is applied to the charged beam between the disappearance and the occurrence of the induced electric field effect. . Furthermore, by performing the above-mentioned adjustment after the high-frequency electric field generated in the acceleration cavity is stabilized, a higher quality charged beam can be obtained. Beams can be efficiently used in free electron laser devices and medical accelerators.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing the configuration of a linear accelerator according to the present invention.

FIG. 2 is a schematic diagram showing a configuration of a conventional linear accelerator.

FIG. 3 is a time chart showing a relationship between disappearance and occurrence of an induced electric field effect and application of a high frequency electric field.

[Explanation of symbols]

11, 21: Charged beam source 12, 22: Pre-buncher 13, 23: Buncher part 14, 24: Regular part 15, 25: High frequency supplying means 16, 26: Reference pulse generating means 17, 27: Timing adjusting means

Claims (3)

[Claims] 1. A pre-buncher 12, a buncher unit 13 and a regular accelerating device using a linear accelerator that sequentially passes a pulsed charged beam emitted from a charged beam source 11 through a pre-buncher 12, a buncher unit 13 and a regular unit 14. Part 14 (Hereinafter, the three parts will be collectively referred to as acceleration cavities)
And a high-frequency electric field is generated in each of the acceleration cavities, and the charged beam source 11 and the high-frequency supplying means 15 are mounted.
To the reference pulse generating means 16, and the timing adjusting means 17 is connected to the reference pulse generating means 16 to determine the timing of emitting the pulsed charged beam and the timing of generating the high frequency electric field in each accelerating cavity. A method for accelerating a charged beam, which comprises accelerating the charged beam by adjusting each based on an induced electric field effect generated in the body. 2. The timing of emitting the pulsed charged beam and the timing of generating a high frequency electric field in each acceleration cavity are based on the induced electric field effect generated in each acceleration cavity and the high frequency characteristics of each acceleration cavity. The method for accelerating a charged particle beam according to claim 1, wherein each of them is adjusted individually. 3. A linear accelerator in which a pulsed charged beam emitted from a charged beam source 11 sequentially passes through a pre-buncher 12, a buncher section 13 and a regular section 14, wherein a high frequency supply means 15 is provided for each acceleration cavity individually. The linear accelerator according to claim 1, wherein the timing adjusting means 17 is individually attached to the charged beam source 11 and each high-frequency supplying means 15, and is connected to the reference pulse generating means 16.