CN109392233B

CN109392233B - Fixed beam phase selection structure of central area of cyclotron

Info

Publication number: CN109392233B
Application number: CN201811103378.9A
Authority: CN
Inventors: 安世忠; 张东昇; 贾先禄; 李明; 王川; 郑侠
Original assignee: China Institute of Atomic of Energy
Current assignee: China Institute of Atomic of Energy
Priority date: 2018-09-20
Filing date: 2018-09-20
Publication date: 2020-10-09
Anticipated expiration: 2038-09-20
Also published as: CN109392233A

Abstract

The invention belongs to the field of physical particle acceleration, and discloses a fixed beam phase selection structure of a central area of a cyclotron, which solves the problem of poor particle extraction effect. The phase screening is carried out at the low-energy end of the cyclotron, so that most of particles with improper phases are deposited in the central area, on one hand, the extraction efficiency is improved, the radioactive dose is not accumulated in the extraction area, on the other hand, the particle screening enables the radial and longitudinal emittance of the beam to be reduced, and the sensitivity of the beam to accelerator parameters such as high-frequency voltage, frequency and the like is reduced.

Description

Fixed beam phase selection structure of central area of cyclotron

Technical Field

The invention relates to the field of physical particle acceleration, in particular to a fixed beam phase selection structure in the central area of a cyclotron.

Background

A cyclotron is a device that uses a magnetic field and an electric field to cause charged particles to make a cyclotron motion together and repeatedly accelerate the charged particles in the motion by a high-frequency electric field.

In the cyclotron using the internal ion source, the accepting phase width of the central area is usually more than 30 degrees, and the phase range with higher extraction efficiency in resonance extraction is only 5-10 degrees, so that part of particles with uncomfortable phase can accumulate radioactive dose in the extraction area, and the debugging operation of the accelerator is influenced.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a fixed beam phase selector in the central area of a cyclotron, which has the function of screening beam phases at a low-energy end and improves the particle extraction efficiency.

A fixed beam phase selection structure of a central area of a cyclotron comprises a high-frequency cavity inside the cyclotron, wherein a phase selector is arranged at the head of the high-frequency cavity and is provided with a slit for screening particles.

The phase screening is carried out at the low-energy end (the number of times of particle acceleration at the head of the high-frequency cavity is small) of the cyclotron, so that most of particles with improper phases are deposited in the central area, on one hand, the extraction efficiency is improved, and the particles are not accumulated in the extraction area, on the other hand, the particle screening enables the radial and longitudinal emittance of the beam to be reduced, and the sensitivity of the beam to accelerator parameters such as high-frequency voltage, frequency and the like is reduced.

Further, the high-frequency cavity head refers to the position of the first three circles of the motion trail of the particles.

The beam current of the first three circles of the central area of the accelerator has certain radial envelope, and the beam current tracks of different circles are not overlapped, so that a slit can be arranged to realize phase screening.

Further, the width of the slit is not more than 0.4 mm.

The beam with the phase width of more than 30 degrees in the central area can be screened to a phase range with the phase width of less than 20 degrees and closer to the phase range with higher extraction efficiency in resonance extraction.

Furthermore, the head part of the high-frequency cavity is provided with a clamping groove, and the phase selector is clamped in the clamping groove.

Therefore, the phase selector is convenient to replace, the particle phases can be flexibly screened by selecting the phase selectors with different slit widths and slit positions, and the central area debugging process is accelerated.

Further, the phase selector has a plate-like structure.

Simple structure and convenient processing.

Further, the difference between the installation azimuth angle of the phase selector and the azimuth angle of the ion source in the cyclotron is 80-100 degrees.

Here the initial radial momentum of the particles causes radial oscillations around a maximum value, and the phase screening effect is the best.

In summary, the following steps: the fixed beam phase selection structure provided by the invention realizes the selection of the beam phase and the phase width in the central area of the accelerator, reduces the beam phase width of an acceleration area and a lead-out area, improves the lead-out efficiency, and reduces the dose of the lead-out area.

Drawings

FIG. 1 is a schematic sectional view of a high-frequency cavity;

FIG. 2 is an enlarged view of portion A of FIG. 1;

fig. 3 is a schematic diagram of particle radial position and phase screening in a beam.

Reference numerals: 1. a high-frequency cavity; 11. a card slot; 2. a phase selector; 21. a slit; 3. an ion source.

Detailed Description

The present embodiment is only for explaining the present invention, and it is not limited to the present invention, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present invention.

A fixed beam phase selection structure of a central area of a cyclotron comprises a high-frequency cavity 1, a clamping groove 11 is formed in the head of the high-frequency cavity 1, and a phase selector 2 is clamped in the clamping groove 11; the phase selector 2 is of a plate-shaped structure, the height of the phase selector 2 is consistent with that of the card slot 11, and the width of the phase selector 2 is smaller than that of the card slot 11, so that the phase selector 2 can perform certain displacement adjustment in the width direction of the card slot 11, namely, certain displacement adjustment can be performed along the radial direction of the cyclotron; the phase selector 2 has a slit 21, the width of the slit 21 being no more than 0.4mm, typically 0.2-0.4 mm. The head of the high-frequency cavity 1 refers to the first three circles of the motion trail of the particles.

The difference between the installation azimuth angle of the phase selector 2 and the azimuth angle of the ion source 3 in the cyclotron is 80-100 degrees, which is selected to be 90 degrees in this embodiment.

For example, as shown in FIG. 3: the ion source 3 has the largest radial oscillation caused by the initial radial momentum at about α =135 degrees azimuth and at 225 degrees azimuth leading 90 degrees (β =45 degrees), and the position of the slit 21 is set, so that a part of particles can be flexibly screened, and further, the phase can be screened.

Claims

1. A fixed beam phase selection structure of a central area of a cyclotron comprises a high-frequency cavity (1) inside the cyclotron and is characterized in that:

a phase selector (2) is arranged at the head of a high-frequency cavity (1), the head of the high-frequency cavity (1) refers to the first three circles of positions of a particle motion track, the first three circles of positions are low-energy ends of a cyclotron, phase screening is carried out at the low-energy ends of the cyclotron, so that most of particles with improper phases are deposited in a central area, on one hand, the extraction efficiency is improved, accumulation is not carried out in an extraction area, on the other hand, the particle screening enables the radial and longitudinal emittance of a beam to be reduced, and the sensitivity of the beam to high-frequency voltage and frequency is reduced;

the difference between the installation azimuth angle of the phase selector (2) and the azimuth angle of the ion source (3) in the cyclotron is 80-100 degrees, the radial oscillation caused by the initial radial momentum of the particles reaches the vicinity of the maximum value, and the phase screening effect is best;

the height of the phase selector (2) is consistent with that of the clamping groove (11), and the width of the phase selector (2) is smaller than that of the clamping groove (11), so that the phase selector (2) can be adjusted in a certain displacement manner in the width direction of the clamping groove (11), namely, the phase selector can be adjusted in a certain displacement manner along the radial direction of the cyclotron;

the phase selector (2) is provided with a slit (21) for screening particles, the width of the slit (21) is not more than 0.4mm, and the width can screen the beam with the phase width of more than 30 degrees in the central area to a phase range with the phase width of less than 20 degrees and higher extraction efficiency in resonance extraction;

the head of the high-frequency cavity (1) is provided with a clamping groove (11), the phase selector (2) is clamped in the clamping groove (11), so that the phase selector can be conveniently replaced, particle phases can be flexibly screened by selecting the phase selectors with different slit widths and slit positions, and the central region debugging process is accelerated;

the phase selector (2) has a plate-like structure.