Anomalous scattering of a relativistic electron beam in a beam created plasma

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.     

临近声速气流条件下电子束空气等离子体特性

为了研究高速动态气流中的电子束等离子体特性,建立了一个由蒙特卡罗模型、多组分等离子体模型与计算流体力学模型组成的多阶段耦合数值模型,在临近声速气流条件下,对1.33104 Pa空气电子束等离子体特性进行了研究。结果表明,电子束能量沉积具有极强的空间不均性,电子束激发下的风洞流场呈现不同的性质,亚声速流场下游边界区密度减小,而在超声速流场中可诱发弱激波;相比于静止气体,在动态气流中等离子体密度下降,且存在额外的输运行为,使其向气流下游输运,但在临近声速条件下,气流速度大小对气流下游等离子体分布的影响不大;电子束入射角对等离子体空间分布和大小均有影响。     

Energetic electron and ion beam generation in plasma openingswitches

In this paper, we present measurements of ion and electron flows in a nanosecond plasma opening switch (NPOS) and a microsecond plasma opening switch (MPOS), performed using charge collectors. In both experiments, an electron flow toward the anode, followed by an ion flow, were observed to propagate downstream toward the load side of the plasma during the plasma opening switch (POS) conduction. In the MPOS, ion acceleration was observed to propagate axially through the entire plasma. These results are in satisfactory agreement with the predictions of the electron magnetohydrodynamics (EHMD) theory and the results of fluid and particle-in-cell (PIC) code simulations. At the beginning of the POS opening, a high-current density (≈2 kA/cm²) short-duration (10-30 ns) axial ion flow downstream toward the load was observed in both experiments, with an electron beam in front of it. These ions are accelerated at the load side of the plasma and are accompanied by comoving electrons. In the NPOS, the ion energy reaches 1.35 MeV, whereas in the MPOS, the ion energy does not exceed 100 keV. We suggest that in the NPOS the dominant mechanism for the axial ion acceleration is collective acceleration by the space charge of the electron beam, while in the MPOS, axial ion acceleration is probably governed by the Hall field in the current carrying plasma     

Filamentation of a rotating electron beam in a magnetized plasma

Filamentation of a nonrelativistic rotating electron beam in a magnetized plasma is investigated by solving the kinetic equation and finding its dielectric permitivity. The period and the establishment time of the filamentation structure and threshold for instability development are obtained. It will be shown that only when the external magnetic field strength becomes smaller than a characteristic value, filamentation appears.     

Transition radiation of modulated electron beam in strongly inhomogeneous plasma

A formula for the transition radiation of a modulated electron bean in a strongly inhomogeneous plasma is derived in a given-current approximation. Nonmonotonic variation of the transition-radiation power is detected when the inhomogeneity parameter for the beam emerging from the plasma is varied. The analytic results are confirmed by numerical calculations.Kiev State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 37, No. 2, pp. 194–199, February, 1994.     

High-current nanosecond pulse-periodic electron accelerators utilizing a tesla transformer

Russian Physics Journal - An analysis is made of the fundamental design principles of the SINUS high-current nanosecond pulse-periodic electron accelerators developed at the Institute of...     

强流电子束二极管等离子体光学诊断

通过处理强流电子束加速器主开关导通之后所形成的高压电脉冲,得到了二极管等离子体光学诊断的同步时间基准。采用高压电脉冲延时结合二极管等离子体光信号延时的方案,实现了相机曝光过程与等离子体发光过程的ns级精度同步。综合采取屏蔽、滤波等措施,实现了整个系统的电磁兼容,最终稳定地拍摄到了ns时间分辨的二极管等离子体发光过程。     

Theoretical analysis of electron acoustic shock waves in magnetized superthermal plasma with electron beam

We have analysed the small-amplitude non-linear electron acoustic shock waves by taking into account the effects of electron beam in magnetized plasma. Satellite observations in different regions of the Earth's magnetosphere have shown that the electrostatic solitary waves are generally associated with electron or/and ion beams. The nonlinear Korteweg-de-Vries Burgers (KdVB) equation has been derived by considering the basic fluid equations and dissipation effects. The nonlinear coefficient of KdVB equation comes out to be negative. Only dip-shaped potential structures are reported here. For the parameters discussed in this paper, we did not find positive polarity shocks. This could be due to the restrictions on the plasma parameters since we are using the fixed densities of the cold, hot, and beam electrons as observed by the Viking satellite in the auroral region. In this paper, the importance of the cold electron to hot electron temperature in conjunction with the beam speed is pointed out. Increase in beam density, kinematic viscosity, and magnetic field results in increase in the amplitude while the increase in hot electron concentration and superthermality leads to decrease in potential. The numerical analysis is presented for the parameters corresponding to the observation of burst b event by Viking satellite in the dayside auroral zone of the earth's magnetosphere.     

Monte Carlo simulation of electron beam air plasma characteristics

A high-energy electron beam generator is used to generate a plasma in atmosphere. Based on a Monte Carlo toolkit named GEANT4, a model including complete physics processes is established to simulate the passage of the electron beam in air. Based on the model, the characteristics of the electron beam air plasma are calculated. The energy distribution of beam electrons (BEs) indicates that high-energy electrons almost reside in the centre region of the beam, but low-energy electrons always live in the fringe area. The energy deposition is calculated in two cases, i.e., with and without secondary electrons (SEs). Analysis indicates that the energy deposition of SEs accounts for a large part of the total energy deposition. The results of the energy spectrum show that the electrons in the inlet layer of the low-pressure chamber (LPC) are monoenergetic, but the energy spectrum of the electrons in the outlet layer is not pure. The SEs are largely generated at the outlet of the LPC. Moreover, both the energy distribution of BEs and the magnitude of the density of SEs are closely related to the pressure of LPC. Thus, a conclusion is drawn that a low magnitude of LPC pressure is helpful for reducing the energy loss in the LPC and also useful for greatly increasing the secondary electron density in dense air.     

Nonlinear interaction of electron beam with magnetized warm plasma

The nonlinear interaction of electron beam with inhomogeneous semi-bounded collisional magnetized warm plasma under external static magnetic field has been studied. The second-harmonic generation at the beam entrance into the plasma is considered. This process leads to an increase in the amplitude of the electric field in the inhomogeneous region and, in turn, to higher absorption.     

Interaction of a modulated electron beam with a plasma

Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 32, No. 11, pp. 1351–1357, November, 1989.     

Inhomogeneous relativistic electron beam interaction with inhomogeneous warm plasma

The interaction of inhomogeneous relativistic electron beam with inhomogeneous bounded warm plasma, which leads to amplification of waves, is analyzed. It is shown that due to the resonant increase in wave’s field with a decrease in the plasma permittivity to zero, the power absorbed by plasma is finite and depends on the plasma thermal velocity. The relativistic electron beam not only amplifies waves in plasma but also provides efficient absorption of these waves by plasma.     

强流电子束二极管等离子体光学诊断

通过处理强流电子束加速器主开关导通之后所形成的高压电脉冲,得到了二极管等离子体光学诊断的同步时间基准。采用高压电脉冲延时结合二极管等离子体光信号延时的方案,实现了相机曝光过程与等离子体发光过程的ns级精度同步。综合采取屏蔽、滤波等措施,实现了整个系统的电磁兼容,最终稳定地拍摄到了ns时间分辨的二极管等离子体发光过程。     

High-current nanosecond electron beams for probing the parameters of solids

Special features and prospects of using high-current nanosecond electron beams for probing the parameters of solids are examined. Of all the variety of signals carrying information on the characteristics of the test object under electron-beam excitation, the potentialities and features of pulsed cathodoluminescence of dielectric and semiconducting materials and of optical absorption (emission) of atoms evaporated by electron beams from metal surfaces or those of conducting rocks are discussed in detail. Tomsk Polytechnical University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 22–30, March, 2000.     

Energy lost by an electron beam in interaction with a plasma

Measurements of the electron beam distribution function after the beam has interacted with a plasma, indicate that a large fraction of the energy lost by the beam has been absorbed by the plasma. Only a small fraction is in the wave field.     

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The generation and control of microwave electron cyclotron resonance (ECR) plasma cathode electron beam is studied experimentally. A complete set of discharge, electron beam extraction, focusing and measuring system was set up. The characteristics and performance of microwave ECR plasmas as electron beam extraction source were studied by measuring the current of water cooling target and the beam spot size on the target. Experimental results indicated that both microwave input power and accelerating voltage are conducive to improving electron beam current. The influence of gas pressure on the electron beam current was complex. With the increase of gas pressure, the electron beam current is characterized by decreasing first and then increasing. The extracted electron current of microwave ECR plasma cathode can reach 75mA at gas pressure of 7×10⁻⁴Pa, and the energy of the electron beam can reach 9keV. The energy utilization can reach 0.6. By adjusting the current of the focusing coil, the diameter of electron beam spot is reduced from 20mm to 13mm and the electron beam current keeps the value unchanged.