SU1077067A1 - Standing wave linear accelerator - Google Patents

Abstract

LINEAR ACCELERATOR ON A STANDING WAVE, containing a generator phase shifter, two accelerating cutting sections, consisting of several cells, an injector and a waveguide bridge, the first arm of which is connected to the generator through the phase shifter, the second and third are connected to the accelerating sections, and the fourth - to the RF power absorber, in order to improve the spectral characteristics of the accelerator, the RF power absorber is made in the form of a section of a circular diaphragmized waveguide with a transformer like an input wave and the output waveguide load located between the injector and the first accelerating section, having holes in the side walls lying on the accelerator axis, the distance between the centers of the last cell of the first accelerating section and the first cell of the second accelerating section being

Description

The invention relates to accelerator technology, namely, accelerated charged particle accelerators with a wave designed for use as sources of ionizing radiation and fluxes of accelerated particles in flaw detection, radiation chemistry and medicine.

Low energy accelerators are known in which magnetrons are used as a generator, supplying accelerating resonator sections ij.

The disadvantage of this device is a wide energy spectrum of accelerated particles.

Closest to the present invention is a compact linear accelerator containing a generator, a phase shifter, a wave bridge, two accelerating resonator sections consisting of several cells, an injector, the first arm of the bridge through the phase shifter being connected to. the generator, the second and the third are connected to the accelerating sections, and the quarter to the RF power absorber 2

A disadvantage of the known device is the wide energy spectrum of accelerated particles due to the transient process in high-quality accelerating sections with Qg-13000, when the crowding fields have different t) T nominal values, a part of the injected electrons, which have energy less than the required, greatly degrade the spectral characteristics of the accelerated beam.

The purpose of the invention. - improvement of the spectral characteristics of the accelerator.

This goal is achieved by the fact that in a linear accelerator on a standing wave containing a generator, a phase shifter, two accelerating resonator sections consisting of small cells, an injector and a waveguide bridge, the first arm of which is connected to the generator through the phase shifter, the second and third are connected to the accelerating sections, and the fourth to the RF power absorber, the RF power absorber is designed as a section of a circular diaphragm waveguide with a wave type transformer at the input and inside the waveguide load at the output located between the injector and the first accelerating section, which has holes in the side walls lying on the accelerator axis, while the distance between the centers of the last cell of the accelerating section and the first cell of the second accelerating section is

e - (2n + 3) a / 4, where n 1,2,3,. . ;

And - the wavelength of the generator.

In the drawing, the proposed accelerator is depicted.

The accelerator contains an RF generator 1, a phase shifter 2, a waveguide bridge 3, accelerating resonator sections 4, a section of a circular diaphragld waveguide (KDV) 5, which, in turn, contains a wave type transformer 6 and intrawave load 7, as well as an injector 8, The shoulders of the high-frequency bridge are numbered in order from the shoulder, which supplies power from generator 1, counterclockwise.

The accelerator works as follows.

RF power from generator 1 through phase shifter 2, waveguide bridge 3, dividing it into two equal parts, is fed to the input of resonator sections 4. At the first moment, all the power from sections 4 is reflected and goes to QDV 5, which has a wave type transformer 6 and the intra-aquatic load 7, in which the power is absorbed. Then the amount of power supplied to the resonator sections 4 increases according to the law

fpPotl-e- oVQH

R"

where ro

-set value;

Qh sho

- loaded with good quality; ;

o is the operating frequency;

and the power going to KDV 5 will decrease to zero with the same constant time. Thus, during the transient process, the establishment of accelerating fields in the resonator sections 4, as well as at the falling front of the envelope of a 1cch pulse in KDV 5, has an electromagnetic field, and the intensity of the electric field on the axis of the KDV 5 can be estimated by the formula

J ui

ITX

Prp fl

where u 1

change in the resonant frequency with the introduction of a perturbing body;

Pgr group speed; 71 - wavelength of the generator; R - RF power; . L is the length of the QDV;

a is the coefficient determined by the method of perturbation in the resonator, the floor in which the poddak is the exact analytical calculation.

The electrons injected by the injector 8 have a relative velocity calculated by the formula

where WK is the kinetic energy of the electron; . gpo - the electron's rest mass, in the region of 0.4, in order for the interaction of electrons with the wave traveling in QDV 5 to be more intense (9 (p of the waveguide is also equal to 0.4. Then at the first time instant with typical for accelerators of this class P P 1MW And -s. 10 cm, i / I 0.038 (H is the thickness of the QDV diaphragm) and we get EQ sf 36 kV / cm. When flying from injector 8 through QDV 5 to the resonator section 4, the injected electrons will result interaction with an electromagnetic field (magnetic or electric or both) deviation From the accelerator axis and fall out of the acceleration process. The cut-off of the bulk of the electrons, which are in the prototype and the base object, is accelerated at non-optimal values for the fields in sections 4, i.e., on the front and rear fronts, envelope The high-frequency impulse, the spectral characteristics of the installation are much worse. In order for the accelerating sections 4 to take into account the load current, they had a critical connection to the supply waveguides, they need to be tuned to a G7Ki.e. .B 1 rbx .e (p. effective shunt resistance; B is the length of the accelerating section; the magnitude of the accelerated current; .., .., - h is the magnitude of the input power of the RF power. For most of the installations we use, for example, for the prototype and the basic object, Ro is 1.5–2, i.e. it is necessary to implement such a mode of operation that, when reflected from resonator sections corresponding to this coefficient, the connection in KDV 5 has such fields that some electrons pass into accelerating sections, then the system will operate in the established mode in the established mode, For the given values in KDV 5, the value will be -2 «10, i.e. The time of filling the QFD with the RF power is several orders of magnitude shorter than the time of the transient process in high-Q resonator sections 4. Thus, the cut-off of electrons with non-optimal parameters will be very effective. In order for Tord, so that the acceleration of electrons in sections 4 u are decaying optimally, the distance between the centers of the last accelerating cell of the first and the first accelerating cell of the second section is chosen equal to 6 ("+) 11/2 + / 4 g (2n +3 ) 1/4, which allows maintaining synchronism between accelerated clots and RF fields, since with such a bridge connection, the field in the second section is ahead by ff / 2 in the first section, the proposed system allows for an order to improve spectral characteristics, accelerators compared to the irotype and the base object.

Claims (1)

A LINEAR ACCELERATOR ON STANDING WAVE, comprising a generator, a phase shifter, two accelerating sharp cells, an injector and a waveguide bridge, the first arm of which is connected to the generator through the phase shifter, the second and third are connected to accelerating sections, and the fourth to the RF power absorber, It is due to the fact that, in order to improve the spectral characteristics of the accelerator, the RF power absorber is made in the form of a section * of a circular diaphragmed waveguide with a wave-type transformer at the input and an intra-water load on the outlet located between the injector and the first accelerating section, having holes in the side walls lying on the axis of the accelerator, the distance between the centers of the last cell of the first accelerating section and the first cell of the second accelerating section is β = (2η + 3) Ά / 4, where P = 1,2,3.,.; Q