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1.
The characteristics of the space-charge oscillations of a long-pulse relativistic electron beam in magnetically insulated
diodes are determined for different geometries of the electron acceleration section and for explosive-emission cathodes of
different materials. The important role of the stream of electrons having high transverse velocities in the evolution of the
oscillations is demonstrated, and the laws governing the generation of this stream are determined. Possible mechanisms of
the space-charge oscillations are described, taking into account the interaction of the electron stream in the beam halo with
the main electron stream, the development of diocotron instability in the stream of electrons emitted by the outer lateral
surface of the plasma emitter, and the instability of the space charge of “long-lived” electrons in the beam transport channel.
Zh. Tekh. Fiz. 68, 102–106 (April 1998) 相似文献
2.
E. Hantzsche 《等离子体物理论文集》1975,15(4):157-175
Some properties of an analytic electrostatic model of relativistic electron beam propagation in vacuum, developed by Poukey and Rostoker [1], are evaluated. It is shown that the limits of validity of this model result from the mixing of electrons, from space charge singularities and the backflow of electrons to the cathode. 相似文献
3.
L. Yu. Bogdanov N. V. Dvoretskaya G. G. Sominskii A. Ya. Fabirovskii 《Technical Physics》1997,42(8):930-934
An experimental investigation is made of the influence of local nonuniformities of a mirror-configuration magnetic field on
oscillations of the space charge and the structure of a long-pulse relativistic electron beam. It is found that the outcome
depends on the axial configuration of the nonuniformity. A nonuniformity near the cathode can substantially reduce the amplitude
of the oscillations and improve the beam transport. The creation of a nonuniformity far from the cathode leads to an accelerated
increase in the oscillations and causes spreading of the transverse structure of the beam. A possible explanation is given
for the mechanism responsible for the influence of these local magnetic field nonuniformities assuming reflection of the cathode
plasma and electron flux from the magnetic mirror, and also allowing for a jump in the drift velocity.
Zh. Tekh. Fiz. 67, 83–88 (August 1997) 相似文献
4.
Ion-focused propagation of a relativistic electron beam in the self-generated plasma in atmosphere
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Jian-Hong Hao 《中国物理 B》2022,31(6):64101-064101
It is known that ion-focused regime (IFR) can effectively suppress expansion of a relativistic electron beam (REB). Using the particle-in-cell Monte Carlo collision (PIC-MCC) method, we numerically investigate the propagation of an REB in neutral gas. The results demonstrate that the beam body is charge neutralization and a stable IFR can be established. As a result, the beam transverse dimensions and longitudinal velocities keep close to the initial parameters. We also calculate the charge and current neutralization factors of the REB. Combined with envelope equations, we obtain the variations of beam envelopes, which agree well with the PIC simulations. However, both the energy loss and instabilities of the REB may lead to a low transport efficiency during long-range propagation. It is proved that decreasing the initial pulse length of the REB can avoid the influence of electron avalanche. Using parts of REB pulses to build a long-distance IFR in advance can improve the beam quality of subsequent pulses. Further, a long-distance IFR may contribute to the implementation of long-range propagation of the REB in space environment. 相似文献
5.
M. A. Vlasov A. A. Korolev Yu. D. Nosach V. V. Popovich A. V. Rykhlov V. A. Safonov 《Radiophysics and Quantum Electronics》1991,34(2):162-167
Results obtained from experimental studies of the interaction between a quasistationary electron beam (300 keV, 20 A, 500 sec, 0.3 cm) and a dense gas are presented. These investigations were carried out in air at atmospheric pressure and, for the purpose of modeling the propagation of a magnetostricted REB, at reduced pressure (3–300 torr). The rarefaction dynamics of a channel heated by the beam are studied and its maximum propagation distances in a dense gas are determined. The results obtained are compared with the theoretical model examined earlier.V. I. Lenin All-Union Institute of Electrical Engineering. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 34, No. 2, pp. 190–197, February, 1991. 相似文献
6.
The temporal evolution of a long-pulse high-density electron beam in a high-power traveling-wave tube with a periodic magnetic
focusing system is investigated. The relation between the variation of the characteristics of the electron beam and ionization
of the residual gas and particles desorbed from the electrode surfaces is shown. A strong influence of the formation of the
collector plasma and the flux of ions from its surface on the beam dynamics is revealed. The effect of microwave fields in
the transport channel on the characteristics of the beam during its evolution is studied.
Zh. Tekh. Fiz. 67, 54–58 (December 1997) 相似文献
7.
8.
Smith J.R. Shokair I.R. Struve K.W. Schamiloglu E. Werner P.W. Lipinski R.J. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1991,19(5):850-854
An intense relativistic electron beam may be transported in low-pressure gas using an ion channel which focuses and guides the beam. The beam can be unstable to the growth of transverse oscillations caused by the electric force between the beam and channel-the ion hose instability. Beam propagation on channels created by photoionization of gas with an excimer laser is discussed. Ion hose oscillations have been recorded which have a betatron wavelength of approximately 1.5 m. The growth rate of the ion hose instability in the linear regime was measured as 1.67±0.45. At this level of growth, the amplitude of beam oscillations equals the channel radius after a period of one-third of an ion oscillation time 相似文献
9.
Di Capua M.S. Camacho J.F. Fulkerson E.S. Meeker D. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1988,16(2):217-224
Microwave emission was measured from a system consisting of an unmagnetized plasma and a propagating electron beam. A 93-cm2 velvet cathode, with an anode-cathode gap of 5.9 cm, injects the electron current into the plasma through an aluminized Mylar anode. Measurements were made of the diode voltage and current in the 6-μV water dielectric accelerator and net current through the beam-plasma system. The unmagnetized plasma is produced by a 90-μs, 90-Å current pulse, emitted from a thermionic LaB6 electron source, that preionizes argon fill in a 1-m-long, 15-cm-diameter Lucite tube. A microwave spectrometer detects the radio-frequency output in the 2-18, 18-26, and 26-47 GHz bands, filters, and then separates into narrower subbands. The emission takes place in two distinct phases. The 2-GHz output rises promptly with the current pulse and then decays. At 6-GHz and above, a low-level microwave prepulse appears simultaneously with the 2-6 GHz output. This output rises sharply 25 ns after the current pulse begins and includes frequencies out to and beyond 40 GHz. The radio-frequency output falls off before the current pulse ends. The microwave intensity decays monotonically with frequency 相似文献
10.
利用数值计算与粒子模拟两种方法,结合实际的实验数据,对高功率微波二极管中相对论电子束与背景气体相互作用碰撞产生的等离子体密度进行了研究.研究结果表明:碰撞产生的等离子体密度数值计算结果与粒子模拟结果基本一致,背景气压在0.01 Pa—0.05 Pa时,碰撞产生的等离子体密度在4—12×109cm-3,即便在考虑电子离子复合的情况下,数值计算结果与粒子模拟结果依然符合得很好.另外,粒子模拟结果表明:随着气压的增加,等离子体密度呈现先增大再减小然后又逐渐增大的过程,
关键词:
相对论电子束
等离子体
数值计算
粒子模拟 相似文献
11.
Physical properties of relativistic electron beam during long-range propagation in space plasma environment
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《中国物理 B》2021,30(10):104103-104103
It is known that ion channel can effectively limit the radial expansion of an artificial electron beam during its longrange propagation in the space plasma environment. Most prior studies discussed the focusing characteristics of the beam in the ion channel, but the establishment process and transient properties of the ion channel itself, which also plays a crucial role during the propagation of the relativistic electron beam in the plasma environment, were commonly neglected. In this study, a series of two-dimensional(2 D) particle-in-cell simulations is performed and an analytical model of ion channel oscillation is constructed according to the single-particle motion. The results showed that when the beam density is higher than the density of plasma environment, ion channel can be established and always continues to oscillate periodically over the entire propagation. Multiple factors, including the beam electron density, initial beam radius, and the plasma density can affect the oscillation properties of ion channel. Axial velocity of the beam oscillates synchronously with the ion channel and this phenomenon will finally develop into a two-stream instability which can seriously affect the effective transport for relativistic electron beam. Choosing appropriate beam parameters based on various plasma environments may contribute to the improvement of the stability of ion channel. Additionally, radial expansion of the beam can be limited by ion channel and a stable long-range propagation in terrestrial atmosphere may be achieved. 相似文献
12.
V. I. Lenin All-Union Institute of Electrical Engineering. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol 34, No. 1, pp. 70–76, January, 1991. 相似文献
13.
Measurements of the velocity angular distribution of a relativistic electron beam (0.8 MV, 6 kA, 150 ns) after propagation through hydrogen gas are presented. At a pressure of 25 Pa scattering of the beam electrons into a preferential angular interval is observed. At 190 Pa anomalously large scattering is observed, up to an angular width of 90°, during about 30 ns. 相似文献
14.
P. Kroček 《Czechoslovak Journal of Physics》1979,29(8):872-882
The theory of the wall instabilities of surface waves excited by an electron beam is developed. Their classification, linear, quasilinear and nonlinear theory is given. It is shown that dissipative instabilities convert practically all the energy lost by the beam into the heating of the lossy walls confining the beam. 相似文献
15.
Transport and virial equations, as well as the equation for the mean total transverse energy of a particle from a transverse segment of an electron beam, are used for deriving an expression for the rms radius of a beam propagating in dense and rarefied gas-plasma media along an external magnetic field. 相似文献
16.
17.
I. M. Poletika M. D. Borisov G. V. Kraev V. P. Meita A. F. Vaisman M. G. Golkovskii 《Russian Physics Journal》1993,36(3):233-238
The possibility was demonstrated of hardening a steel surface layer by alloying it using the energy of relativistic electrons. Investigations were made of how the structure, hardness, and depth of the hardened layer depend on the processing regime and on the initial temperature of the steel in the case of alloying with boron carbide and with Cr+C and Cr+B4C mixtures. The greatest hardening was achieved by alloying with a mixture of Cr and B4C powders. This was due to a higher volume fraction of the second phase in the layer and to the precipitation of chromium carboborides. Several types of alloying utilizing Cr+B4C and containing additional agents and modifiers were developed on the basis of the data obtained.Institute of Hardening Physics and Materials Research, Siberian Branch of the Russian Academy of Sciences. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 57–63, March, 1993. 相似文献
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20.
V. V. Ognivenko 《Journal of Experimental and Theoretical Physics》2012,115(5):938-946
The motion of the relativistic electron beam in the spatially periodic magnetic field of an undulator has been considered taking into account the effect of the incoherent field of the spontaneous undulator radiation on the motion of the electrons. An expression for the rms momentum of the electrons has been obtained. It has been shown that the momentum spread in the ultrarelativistic electron beam increases in the spontaneous incoherent emission mode. Conditions for the self-amplification of the spontaneous undulator radiation in ultrashort-wavelength free-electron lasers have been discussed. 相似文献