共查询到20条相似文献,搜索用时 15 毫秒
1.
N.I. Karbushev 《Physics letters. A》2008,372(24):4484-4486
The specific features of the beam-plasma instability in waveguide under very high beam current are shown analytically. The differences (as compared to conventional case of beam-plasma instability under low beam current) are due to change of physical mechanisms of beam-plasma interaction. 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.
Analysing the general dispersion relation numerically, the unstable regions of the relativistic electron-beam plasma system were determined. The external parameters were varied to ensure more effective instability excitations. The full charge and current compensation presumptions lead to new synchronism predictions. The return current's slow space charge wave and return current's slow cyclotron wave are synchronous with the plasma ion wave. 相似文献
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K. Yatsui M. Yatsuzuka T. Fujii M. Yokoyama M. Masuzaki T. Tsuzuki K. Narihara A. Mohri 《Physics letters. A》1979,73(4):321-323
We study experimentally the interaction of a current-modulated relativistic electron beam with a mirror-confined plasma. A high-power transmitter (500 MHz, 1 GW) is developed. Rapid heating takes place up to ≈ 900 eV, which is interpreted as a lower-hybrid parametric instability. 相似文献
6.
Experimental results on interaction of a rotating relativistic electron beam with plasma and neutral gas are presented. The
rotating relativistic electron beam has been propagated up to a distance of 150 cm in a plasma. The response of the plasma
to the rotating electron beam is found to be of magnetic diffusion type over a plasma density range 1011–1013 cm−3. Excitation of the axial and azimuthal return currents by the rotating beam and subsequent trapping of the azimuthal return
current layer by the magnetic mirror field are observed. A field-reversed configuration has been formed by the rotating relativistic
electron beam when injected into neutral hydrogen gas. We have observed field reversal up to three times the initial field
in an axial length of 100 cm. 相似文献
7.
Ion-focused propagation of a relativistic electron beam in the self-generated plasma in atmosphere 下载免费PDF全文
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
8.
Physical properties of relativistic electron beam during long-range propagation in space plasma environment 下载免费PDF全文
《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
9.
A theoretical model is given, along with a numerical analysis of the evolution of beam-plasma discharge in the propagation
of a long-pulse relativistic electron beam in a rarefied gas at medium pressure. It is shown that the self-stabilization of
beam-plasma discharge as a result of longitudinal inhomogeneity of the density of the discharge plasma makes it possible for
the beam to traverse the beam chamber with relatively low total energy losses, including ionization losses and energy losses
in the generation of oscillations. During the dissociative recombination of electrons and ions of the discharge-driven plasma,
heat is released and spent in raising the temperature of the gas. The investigated collective-discharge mechanism underlying
heating of the gas for a relativistic beam can be more efficient than the classical heating mechanism due to ionization losses
of the beam in pair collisions of its electrons with gas particles.
Zh. Tekh. Fiz. 67, 94–98 (May 1997) 相似文献
10.
当强流相对论电子束在类双腔速调管系统中传输时,会发生自调制现象. 利用这一现象可以 在无微波注入的情况下得到较好的微波输出,这是一种由强流相对论效应引起的自激振荡. 利用这一原理有可能研制出一类新型的微波器件. 对强流相对论电子束在这种物理机制作用 下发生起振的条件及传输机理进行了理论分析,并进行了数值模拟. 优化结果显示,利用4k A, 500kV的强流相对论电子束,可得到099GHz,800MW的微波输出,效率约40%.
关键词:
强流相对论电子束
自调制
反馈机制
数值模拟 相似文献
11.
We have observed experimentally the explosive instability of the slow space charge wave of the electron beam and the electrostatic electron cyclotron harmonic wave due to nonlinear wave-particle interaction. These waves interact nonlinearly with the electron beam and grow simultaneously. 相似文献
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在惯性约束聚变(ICF)电子束快点火物理方案中,需要超强拍瓦激光脉冲驱动MeV能量的强流电子束,并沉积数十kJ能量到压缩氘氚芯区。强流电子束的束流品质是影响点火成功的关键因素之一,为深入了解强流电子束产生物理过程,研制成了三维高性能、适应上万CPU核规模的并行粒子模拟程序,并开展了大规模数值模拟研究,探索了强流电子束的产生机制和输运规律。回顾了近几年来快点火研究团队围绕强流电子束产生和控制开展的研究,介绍了导致束流品质差的两大物理原因:预等离子体效应和束流不稳定性磁场的随机散射。针对这两个物理原因,提出了四种提高强流电子束品质的方法:(1)双层金锥靶减弱预等离子体的负面效应;(2)输运丝产生环向磁场准直强流电子束;(3)外加磁场导引强流电子束提高耦合效率;(4)抑制束流不稳定性以降低随机磁场对电子束流的散射。 相似文献
15.
在惯性约束聚变(ICF)电子束快点火物理方案中,需要超强拍瓦激光脉冲驱动MeV能量的强流电子束,并沉积数十kJ能量到压缩氘氚芯区。强流电子束的束流品质是影响点火成功的关键因素之一,为深入了解强流电子束产生物理过程,研制成了三维高性能、适应上万CPU核规模的并行粒子模拟程序,并开展了大规模数值模拟研究,探索了强流电子束的产生机制和输运规律。回顾了近几年来快点火研究团队围绕强流电子束产生和控制开展的研究,介绍了导致束流品质差的两大物理原因:预等离子体效应和束流不稳定性磁场的随机散射。针对这两个物理原因,提出了四种提高强流电子束品质的方法:(1)双层金锥靶减弱预等离子体的负面效应;(2)输运丝产生环向磁场准直强流电子束;(3)外加磁场导引强流电子束提高耦合效率;(4)抑制束流不稳定性以降低随机磁场对电子束流的散射。 相似文献
16.
A modulation of an electron beam density at frequencies lower than an ion cyclotron frequency enhanced the low frequency instability of broad band and heated plasma ions in a beam-plasma system. The heating of ions is explained by the stochastic process of a weakly turbulent plasma. 相似文献
17.
The influence of self-fields on the equilibrium and stability properties of relativistic beam-plasma systems is studied within the framework of the Vlasov-Maxwell equations. The analysis is carried out in linear geometry, where the relativistic electron beam propagates through a background plasma (assumed nonrelativistic) along a uniform guide field , It is assumed that for the beam electrons (ν is Budker's parameter, and γ0mc2 is the electron energy), but no a priori assumption is made that the beam density is small (or large) in comparison with the plasma density, or that conditions of charge neutrality or current neutrality prevail in equilibrium. It is shown that the equilibrium self-electric and self-magnetic fields, and , can have a large effect on equilibrium and stability behavior. Equilibrium properties are calculated for beam (j = b) and plasma (j = e, i) distribution functions of the form fb0(H, Pθ, Pz) = F(H ? ωrbPθ) × δ(Pz ? P0)(j = b), and (j = e, i), where H is the energy, Pθ is the canonical angular momentum, Pz is the axial canonical momentum, and ωrj (the angular velocity of mean rotation for j = b, e, i), Vj (the mean axial velocity for j = e, i), and P0 are constants. The linearized Vlasov-Maxwell equations are then used to investigate stability properties in circumstances where the equilibrium densities of the various components (j = b, e, i) are approximately constant. The corresponding electrostatic dispersion relation and ordinary-mode electromagnetic dispersion relation are derived (including self-field effects) for body-wave perturbations localized to the beam interior (r <Rb). These dispersion relations are analyzed in the limit of a cold beam and cold plasma background, to illustrate the basic effect that lack of charge neutrality and/or current neutrality can have on the two-stream and filamentation instabilities. It is shown that relative rotation (induced by self-fields) between the various components (j = b, e, i) can (a) result in modified two-stream instability for propagation nearly perpendicular to , and (b) significantly extend the band of unstable kz-values for axial two-stream instability. Moreover, in circumstances where the beam-plasma system is charge-neutralized but not current-neutralized, it is shown that the azimuthal self-magnetic field has a stabilizing influence on the filamentation instability for ordinary-mode propagation perpendicular to . 相似文献
18.
The nonlinear Landau damping of space charge waves of an electron beam into Trivelpiece modes by nonlinear interaction with plasma electrons has been observed experimentally in an electron beam-plasma system. 相似文献
19.
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
20.
Shi-Chang Zhang 《International Journal of Infrared and Millimeter Waves》1986,7(10):1497-1510
This paper proposes an azimuthal bunching-mechanism of a relativistic electron beam with circular orbits in the centrifugal electrostatic focusing system (CEFS). A kinetic theory is given which is in principal agreement with the proposed bunching-mechanism. A new proposal is presented that the electron beam is obliquely injected into CEFS. 相似文献