SU1343569A1 - Method of exciting high-frequency accelerating field in periodic structure of linear ion accelerator - Google Patents

Abstract

The invention relates to the field of accelerator technology. The aim of the invention is to increase the efficiency and increase the stability of the acceleration mode of the fast high frequency (HF) field in the periodic structure of a linear ion accelerator. It is achieved by the fact that when creating a magnetic field (MP), its intensity varies in length according to a certain mathematical law, while the electrons of the generating beam (P) are preliminarily directed along a spiral trajectory around the field lines MP The ion accelerator is guided to an electrodynamic structure with a transverse type of oscillation and a phase velocity of the longitudinal velocity P placed in a resonant MF. The description of the invention provides a mathematical expression for the longitudinal component of the MP intensity. The invention can be used for the acceleration of ions, for the generation of RF oscillations, for the excitation of fast and slow cyclotron charge density waves in electronic P, 2 3, P f-ly. x; oo co-eaten O5 CO

Description

 13

The invention relates to accelerator technology and can be used to accelerate ions, to generate high-frequency (HF) oscillations and to excite fast and slow cyclotron charge density waves in the electron poHHtt beams.

The purpose of the invention is to increase the efficiency of excitation of the HF-field and increase the stability of the excited HF-field acceleration.

Example. The excitation of the HF field in a proton accelerator on the N wave, consisting of three resonator sections and an RF recuperator operating at the same frequency, is produced by an intense electron beam. An electron beam with an energy of 1 MeV and a current of 40 A is injected in the direction of the acceleration of protons. Longitudinal magnetic

The field H is created by an external solenoid and varies along the length of the solenoid in accordance with the ratio

21Go.

H. () (Z) -,

.2Ulll) ki; xi 2f (,)

spatial coordinate along the system axis, m; the longitudinal component of the magnetic field strength as a function of Z, T;

2irn

DCZJ:

Zo

D (Z) x „a

} f v (Z)

e

m

the longitudinal constant of the nth spatial harmonic, the longitudinal constant of the zero spatial harmonic, in the positive direction of the Z axis; structure period length, m, increasing with in the positive direction of the Z axis | the transverse constant of the propagation of the nth spatial harmonic, m-; oscillation frequency, glad С j relativistic factor ;. the longitudinal velocity of the electron beam, in the positive, in the negative direction of the Z axis;

electron charge, C; electron's rest mass, kg;

WITH ,, - Langmuir frequency °

electron beam glad rad

n is the number of spatial ammonium;

S is the cyclotron harmonic number.

In this example, v 0,,,,,.

The relation (1) is fulfilled along the entire length of the accelerator. In this case, an electron beam at a cyclotron instability with a high degree

selectivity (-10)

The basic type of oscillations () for a time less than 0.1 µs is ignited. The structure of the fields near the axis provides Coulomb and resonant high-frequency radial focusing for accelerated ions.

The limiting current of the accelerated beam in this case is determined only by its longitudinal stability. The acceleration of ions can be carried out on the spatial harmonic. The intensity of the magnetic field, based on relation (1), with,, create such that in the 1st section of the accelerator, the RF field is generated on the + 1-st spatial and -1-th cyclotron harmonics. The generation is accompanied by a decrease in the longitudinal and increase in transverse electron pulses, with the result that a beam of electrons swirled around the magnetic field lines arrives in the 2nd section. In the 2 nd section, the magnetic field, the origin of (1), when created, is created by the generator, so that the RF field is generated at the 1 st spatial and + 1 st cyclotron harmonics. This changes the value, but not the direction of the magnetic field. At the same time, the transverse electron pulses are converted to longitudinal ones.

In the 3rd section of the accelerator, the magnetic field strength again corresponds to the generation of the RF field at the + 1st spatial and -1st cyclotron harmonics and the conversion of longitudinal electron pulses into transverse ones. In general, along the length of the accelerator, the magnetic field strength decreases in accordance with the increase in the period of the structure.

After the selection from the 3rd section, the electron beam is directed to the RF recuperator, which is an RF structure with a phase velocity greater than or equal to the electron velocity, with a purely transverse type of oscillation at the frequency of - the operating frequency of the accelerator, and the external magnetic field corresponding to the relation (1). In the RF recuperator, the beam is finally braked, and the resulting RF power is transmitted along the RF path to an accelerator, thereby increasing the overall efficiency

Formula inventions

Claims (2)

1. A method of exciting an accelerating high-frequency field in a periodic structure of a linear ion accelerator predominantly on the wave THna.ff, including creating a magnetic field and longitudinal injection of an intense electron beam, characterized in that, in order to increase the efficiency and increase the stability of the acceleration mode, the magnetic field intensity the sex is changed in length according to H, (Z), v (Z) xSh1 1M-x | 1 2f (C + x2 „) J de Z - spatial coordinate along the system axis, m; H (Z) is the longitudinal component of the magnetic field strength as a function of Z, T; 40 v (Z) is the longitudinal velocity of the electron beam, in the positive, .0 in the negative direction of the Z axis; .45 e is the electron charge, Cl; m is the rest mass of an electron, kg; Compiled by E, Gromov Editor P, Gereshi Tehred M, Didyk Corrector M, Pojo Order 4837/57 Edition 801 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab ,, d, 4/5 Production and printing company, Uzhgorod, Proektna st, 4 Q 5 0 5 f - relativistic factor; 0 five 0 5 oscillation frequency, radar C - ABOUT  go + 27p + - Т-Г - longitudinal constant of the nth spatial harmonic, - longitudinal constant of the zero spatial harmonic, in the positive direction of the Z axis; D (Z) is the length of the structure period, m, increasing in the positive direction of the Z axis; x is a constant constant for the propagation of the nth spatial harmonic, m; Orient frequency electron beam, radar C; n is the number of spatial harmonics, mainly S is the cyclotron harmonic number, predominantly, with the distribution mode H (Z) corresponding to,,, or the distribution mode H (Z) corresponding to, ncO, set on the entire length of the system or alternate these modes along the length of the system. 2. The method according to claim 1, differing in the condition that the electrons of the generating beam are pre-directed along a spiral trajectory around the magnetic field lines, 3, Method pop, 1, characterized in that, in order to increase efficiency by converting the residual kinetic power to high frequency, the electron beam, after exiting the ion accelerator, is directed to an electrodynamic structure placed in a resonant magnetic field with a transverse type, oscillations and a phase velocity equal to the longitudinal velocity of the beam.