RU2395937C1 - Linear resonance accelerator - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: proposed accelerator comprises resonator representing coaxial delay line and system of excitation therefor. The latter comprises oscillator, system of cathodes and vacuum windows to let electron beams out into atmosphere. Said delay line is made up of toroidal inductance coils. Every said coil incorporates metal shield to screen radial electric field of said coaxial resonator. Said oscillator can be connected via feeder to delay line start.

EFFECT: lower resonance frequency and use of transistorised constant-to-variable voltage converter to exciter resonator.

13 cl, 1 dwg, 1 ex

Description

Technical field

The invention relates to the field of accelerator technology, namely, the accelerator technique for radiation technology with the removal of electrons from the accelerator body, which can be used in new plasma-chemical technologies and, in particular, in technologies for the modification and production of new materials, disinfection of medical and other products, industrial and medical waste treatment, environmental protection.

State of the art

Linear resonant accelerators are known that contain a resonator in the form of a coaxial delay line with an internal conductor in the form of a cylindrical spiral, an excitation system in the form of a primary low-voltage winding, powered by alternating current, a system of cathodes and vacuum windows for outputting an electron beam into the atmosphere (see. beam Electron Accelerator fort Industrial Application "Proceedings of the European Particle Accelerator Conference, Viena, 26-30 June, 2000, p. 2600; GVDolbilov, GIDolbilova, INIvanov, AVMazhulin, JINR, Dubna, Russia; T. Ruskov, INRNE, Sofia, Bolgaria ; "Multi-beam Electron Accelerator for Radiation Processing", Proceedings of 2001 Particle Accelerator Conference, 2001, Hyatt Regency, Chicago, Illinois, USA, June 18-22, 2001, p.651; GVDolbilov, GIDolbilova, INIvanov, AVMazhulin, VN Razuvakin; Joint Institute for Nuclear Research, Dubna, 141980, Russia; "High Repetition Pulsed Accelerator for EB-Technology", Proceedings of a Symposium on Radiation Technology for conservation of the environment, 8-12 September 1997, p. 453, Zakopane, Poland. GVDolbilov, GIDolbilova, AAFateev, INIvanov, NILebedev, AVMazhulin, VAPetrov, IMHohlov. Joint Institute for Nuclear Research, Dubna, Russian Federation; T. Ruskov, Institute of Nuclear Research and Nuclear Energy, P. Goranov, Technical University, Sofia, Bolgaria; "High Repetition Pulsed Accelerator for Industrial Application", Proceedings of the II Scientific Seminar in Memory of V.P. Sarantsev, Dubna, September 23-24, 1997, G.V.Dolbilov et al .; Multi-Beam Pulsed Accelerator for Electron Beam Prisesssing, Proceedings of 6 ^th European Particle Accelerator Conference, Stockholm, 22-26 June, 1998, p.2398, GVDolbilov, GIDolbilova, AAFateev, INIvanov, NILebedev, AVMazhulin, VAPetrov, IMHokhlov, IMHokhlov, Dubna, Russia, T. Ruskov, INRNE, P. Goranov, TU, Sofia, Bolgaria). The primary winding and the outer conductor of the resonator in such accelerators are located on the dielectric vacuum housing of the accelerator.

Closest to the proposed invention is a resonant accelerator described in "Multi-beam Electron Accelerator fort Industrial Application" Proceedings of European Particle Accelerator Conference, Viena, 26-30 June, 2000, p.2600; G. V. Dolbilov, G. I. Dolbilova, I. N. Ivanov, A. V. Mazhulin, JINR, Dubna, Russia; T. Ruskov, INRNE, Sofia, Bolgaria (prototype). It consists of a coaxial resonator based on a delay line excited by primary turns located on a dielectric vacuum casing. The inner conductor of the resonator is a cylindrical spiral wound on a dielectric rod, the outer conductor of the resonator is located on the vacuum casing of the accelerator. A cathode system is located at the high voltage end of the inner conductor. Each cathode has its own vacuum window for outputting the beam into the atmosphere.

The prototype and accelerators described in the above papers have one common drawback, namely, that the intense axial magnetic flux and scattered magnetic fields induce currents in the parts of the accelerator and in the equipment and radiation protection surrounding the accelerator. This leads to additional power losses and heating of electrically conductive parts and components of the installation. In addition, the conductor of the internal electrode, while in the vacuum volume, is not protected from the effects of secondary particles, which can violate the insulation of the conductor and reduce the reliability of the accelerator.

Disclosure of invention

The invention solves the problem of reducing power loss, increasing efficiency and reliability of the accelerator.

This goal is achieved in that the linear resonant accelerator comprises a resonator made on the basis of a coaxial delay line, a system of its excitation, including a generator, a system of cathodes and vacuum windows; the delay line is made of toroidal inductors, with each coil equipped with a metal screen, and the generator, through a feeder, has the ability to connect to the beginning of the delay line; each toroidal coil consists of two semi-windings that are connected in parallel, and the windings of the semi-windings are mutually opposite direction; the number of toroidal coils is determined by the ratio N = (π / 2) · (U _accele / ΔU), where U _accele is the specified value of the accelerating voltage, ΔU is the maximum allowable voltage between the coil windings, which is determined by the type of insulating material (liquid or gaseous), specific the design of the toroidal coils and the distance between them.

The distinguishing features of the invention are the following: the delay line is made of toroidal inductors, each coil equipped with a metal screen, and the generator, through a feeder, has the ability to connect to the beginning of the delay line;

each toroidal coil consists of two semi-windings that are connected in parallel, and the windings of the semi-windings have a mutually opposite direction;

the number of toroidal coils is determined by the ratio N = (π / 2) · (U _accele / ΔU), where U _accele is the specified value of the accelerating voltage, ΔU is the maximum allowable voltage between the coil windings, which is determined by the type of insulating material (liquid or gaseous), specific the design of the toroidal coils and the distance between them.

The internal conductor of the delay line is made of toroidal inductors, which eliminates the axial component of the magnetic flux and scattered magnetic fields, because The magnetic field of the toroidal coils has an azimuthal component and is concentrated inside the volume of the coils. This eliminates the induction of currents in the electrically conductive structural elements of the accelerator, their heating, power loss and leads to an increase in the efficiency of the accelerator.

Each coil is equipped with a metal screen for shielding the radial electric field of the coaxial resonator, which reduces the electric field strength in the coils and increases the reliability of the accelerator.

The generator, through a feeder, has the ability to connect to the beginning of the delay line, which allows you to excite a coaxial resonator.

Each toroidal coil consists of two semi-windings that are connected in parallel, which allows to reduce the electric field strength between the beginning and the end of the toroidal coil winding and to increase the reliability of the accelerator.

The windings of the semi-windings have a mutually opposite direction for matching their magnetic fluxes.

The number of toroidal coils is determined by the ratio N = (π / 2) · (U _accele / ΔU), where U _accele is the specified value of the accelerating voltage, ΔU is the maximum allowable voltage between the coil windings, which is determined by the type of insulating material (liquid or gaseous), specific the design of the toroidal coils and the distance between them. This allows you to provide the necessary electrical strength of the system and increase the reliability of the accelerator.

The combination of the above features allows to eliminate the axial magnetic flux and scattered magnetic fields, reduce power loss, increase the efficiency and reliability of the accelerator.

Description of the drawing

The accelerator circuit is shown in the drawing, where:

(1) - external conductor of the delay line of the coaxial resonator (accelerator vacuum casing);

(2) - dielectric "glass";

(3) - toroidal coils of the inner conductor of the delay line;

(4) - metal screens;

(5) a cathode electrode with a cathode system;

(6) - vacuum windows;

(7) - feeder;

(8) - alternator.

The metal vacuum casing (1) is the external conductor of the coaxial resonator (delay line). A dielectric cup (2) is located inside the vacuum casing, inside of which are connected toroidal coils (3) in series, and metal screens (4) are located outside the cup. Metal screens are galvanically connected to the terminals of the toroidal coils. The cathode electrode (5), on which the system of cold cathodes is located, is located on the end part of the dielectric cup (2). Vacuum windows (6) are located on the end of the vacuum casing. The feeder (7) of the alternator (8) is connected to the beginning of the delay line of the resonator.

The implementation of the invention

The device operates as follows.

The generator (8) by means of a feeder (7) connected to the input of the delay line, excites current in the internal (3) and external (1) conductors of the delay line. At the resonant frequency, when the electric wavelength in the delay line is four geometric line lengths, the input impedance of the line decreases, and the current and voltage in the line increase. In resonance, the current and voltage along the line length change according to the law I (z) = I ₀ Coskz, U (z) = I ₀ ρSinkz, where I ₀ is the current at the input to the delay line, ρ is the wave impedance of the line, k = 2π / λ is the propagation constant of the wave in the line, λ is the wavelength in the delay line, z is the axial coordinate of the line. With the line length z = L = λ / 4, the voltage at the high-voltage end of the line is U (L) = U _accele = I ₀ ρ. For example, with a wave impedance of the line ρ = 100 kOhm and a current at the input of the line I ₀ = 5 A, the voltage at the high-voltage end of the line is U (L) = 500 kV.

At the output of the coaxial line there is a cathode electrode with a system of cold cathodes (5). The beam current of each electrode is discharged into the atmosphere through its own window (6). The small size of the cold cathodes and their corresponding windows makes it possible to use extremely thin metal foils of windows and to reduce the energy loss of electrons when they are released into the atmosphere. Metal screens (4) protect the coils (3) from the radial electric field of the resonator. Dielectric cup (2) may be absent if vacuum insulation is used as insulation for coils (3). The option of gaseous or liquid insulation requires the use of a vacuum-tight dielectric cup.

Concrete example

The windings of toroidal inductors are made of insulated copper wire. The diameter of the wire depends on the selected number of turns, which determines the wave impedance of the delay line.

The generator is a transistor DC to AC converter. Metal screens are made of copper or stainless steel.

The number of toroidal coils in the delay line is determined by the maximum allowable voltage between the coil windings ΔU, which depends on the type of insulating material (liquid or gaseous), the specific design of the toroidal coils and the distance between them N = (π / 2) · (U _accele / ΔU). For example, with U _accele = 500 kV and ΔU = 50 kV, 15-16 coils are required. Vacuum windows are made of thin metal foil. For example, for windows with a diameter of 3 cm, the thickness of the titanium foil may be 10-15 microns.

The cathode system is a set of evenly spaced small cathodes, each cathode having its own vacuum window. When using cold cathodes with threshold emission characteristics and an appropriate choice of the electric field strength on the surface of the cathodes, electron emission will occur only at voltages above the threshold value. The ratio between the threshold and maximum voltage values is regulated by changing the maximum voltage on the surface of the cathodes, determined by the distance of the anode-cathode.

Claims (3)

1. A linear resonant accelerator containing a resonator in the form of a coaxial delay line, its excitation system, including a generator and a system of cathodes and vacuum windows for outputting an electron beam into the atmosphere, characterized in that the delay line is made of toroidal inductors, each coil equipped with a metal screen to shield the radial electric field of the coaxial resonator, and the generator through the feeder has the ability to connect to the beginning of the delay line. 2. The linear resonant accelerator according to claim 1, characterized in that each toroidal coil consists of two semi-windings that are connected in parallel, and the windings of the semi-windings have a mutually opposite direction for the possibility of matching their magnetic fluxes. 3. The linear resonant accelerator according to claim 1, characterized in that the number of toroidal coils is determined by the ratio N = (π / 2) · (U _accele / ΔU), where U _accele is the specified value of the accelerating voltage, ΔU is the maximum allowable voltage between the windings coils, which is determined by the type of insulating material (liquid or gaseous), the specific design of the toroidal coils and the distance between them.

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