共查询到20条相似文献,搜索用时 15 毫秒
1.
B. A. Demidov M. V. Ivkin I. A. Ivonin V. A. Petrov V. P. Efremov V. E. Fortov N. Keeler 《Technical Physics》1997,42(11):1264-1269
Optical methods are used to investigate the dynamics of the interaction of a high-current electron beam with an aerogel (a
highly porous transparent dielectric with a low density ρ=0.36 g/cm3). The measured profile of the glow of the aerogel and the pattern of its expansion are compared with the results of a numerical
simulation. The influence of the space charge on the profile of the energy absorption from the high-current relativistic electron
beam is discussed.
Zh. Tekh. Fiz. 67, 26–32 (November 1997) 相似文献
2.
N. S. Azaryan S. A. Barengolts S. N. Dolya G. A. Mesyats E. A. Perelstein 《Technical Physics》2010,55(4):557-564
The possibility of using picosecond high-current relativistic electron beams for the formation of tubular rotating relativistic electron rings is investigated. Longitudinal compression of a tubular beam in a cusp is simulated numerically disregarding the space charge effects. The behavior of the characteristics of a compressed beam, which determines the tolerances in the initial parameters and magnetic system parameters, is investigated. 相似文献
3.
We analyze the properties of a high-current electron beam formed in an electron source based on a plasma-filled diode and a linear pulsed transformer. The beam parameters are determined by measuring bremsstrahlung X-rays and the beam current, as well as the photographs of the diode gap in the optical range, of the anode in X-rays, and beam autographs. A beam with a current of ~100 kA and a mean electron energy exceeding 0.7 MeV for an accelerating voltage amplitude of ~1 MV is obtained. The diameter of the generated beam is ~1 cm. The electron beam from the plasma-filled diode makes it possible to attain a high anode power density (>1010 W/cm2) for exciting shock waves, for obtaining high pressures, and for generating powerful X-rays. 相似文献
4.
O. T. Loza 《Technical Physics》2008,53(11):1479-1484
Cold explosive emission cathodes, in which a plasma serves as an emitting surface, are used to generate relativistic electron
beams with a high current density in a magnetic field. The plasma parameters change within a microsecond, thereby significantly
changing the geometry of the electron beam. This paper is a review of techniques for stabilizing the geometry of microsecond
high-current relativistic electron beams. It is shown that only a transverse-blade explosive emission cathode in a magnetically
insulated diode can generate such beams (500 keV, 3 kA) the current density profile and electron trajectory pitch factor of
which remain constant for a microsecond. 相似文献
5.
We analyzed the possibility of improving the efficiency of microwave devices operating with relativistic electron beams in systems with particle postacceleration in the interaction space. The fundamental feature of this approach is the formation of the accelerating-potential profile with the inherent electric field of a high-current electron beam. It is shown that the use of the space-variant beam-potential sag helps raise the estimated efficiencies of relativistic Cherenkov TWT and BWO up to values of about 50%. 相似文献
6.
Investigations of the generation and transport of a high-current, low-energy electron beam are performed in a system with
a gas-filled diode based on a plasma cathode. At accelerating voltages of up to 20 kV and pressures of (1–5)×10−1 Pa, a beam with an emission current of 600 A, emission current density of 12 A/cm2 and pulse duration of 30 μs if obtained in a diode with a grid-stabilized emission opening having a diameter equal to 8 cm.
The beam is transported in the absence of an external magnetic field over a distance of 20 cm. The beam is compressed by its
self-magnetic field, and the current density at the collector reaches 100 A/cm2 when the beam diameter is 3 cm.
Zh. Tekh. Fiz. 68, 44–48 (January 1998) 相似文献
7.
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
8.
V. T. Uvarov A. G. Ponomarev Yu. F. Lonin V. V. Uvarov A. N. Nikitin V. N. Robuk T. I. Ivankina V. F. Klepikov V. V. Lytvynenko S. E. Donets M. I. Bazaleev 《Physics of Particles and Nuclei Letters》2014,11(3):274-281
The characteristic manifestations of radiation-acoustic effects in metals and alloys under the irradiation of a high-current relativistic electron beam, leading to a melt surface with the partial removal of material from the surface, are studied in this paper. An increase in the acoustic emission in the samples when they are irradiated with a high-current electron beam is experimentally observed. It is shown that the primary mechanism for the generation of radiation-acoustic pulses in irradiated refractory metals is a stress-relieving mechanism. The amplitudes of the acoustic pulses after the second and subsequent electron pulses do not change, which indicates a correlation between the amplitude of the acoustic signal and the surface structure of the irradiated material. 相似文献
9.
D. I. Vaisburd 《Russian Physics Journal》1996,39(11):1093-1101
This article is a survey of works by the author and colleagues on the investigation of charging and discharging dynamics in
solid dielectrics exposed to dense electron beams with subnanosecond resolution. Small high-current electron accelerators
of theDzhin type, which were developed and fabricated at the Nonlinear Physics Laboratory, were used as the source of the primary electron
beam. The primary electron beam parameters were: 0.25–0.45 MeV, 1–30 nsec, 0.1–10,000 A/cm3. The dielectric is investigated experimentally with its surface covered by a metallic electrode and with critical electron
emission into the vacuum eliminated. In this case, the total current in the dielectric consists of three components: the primary
beam current, the displacement current, and the conduction current. The first and last are responsible for charging and discharging
of the dielectric volume. It is shown that the bulk nonequilibrium radiation conduction mechanism depends greatly on the dose
intensity. For small dose intensities, the principal current carriers are the low-energy electrons of the conduction band
and holes of the valence band, which are in quasi-equilibrium with the lattice phonon field before capture by defects or merging
into excitons preceding recombination. This type of conduction has been well studied in the physics of semiconductors and
dielectrics. However, over a broad interval of intermediate and high dose intensities, another type of nonequilibrium conduction
dominates — the high-energy, which was discovered and studied by the author and colleagues. The principal carriers are then
passive-ionization electrons and holes with energies of 0.1–10 eV in the process of phonon relaxation in which phonon emission
dominates absorption. The high-energy conduction differs considerably from the low-energy in many properties, which determines
the unusual dynamics of dielectric charging and discharging with irradiation by the dense electron beam of a high-current
accelerator.
Institute of High-Current Electronics, Siberian Section, Russian Academy of Sciences. Tomsk Polytechnic University. Translated
from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 109–119, November, 1996. 相似文献
10.
The dynamics of a high-current (102–104 A) electron beam with energies of 105–106 eV and picosecond duration (10−10 s) at the output of the accelerator tube is investigated. The slowing of electrons by the residual positive charge on the
surface of the tube is found to have a significant influence in the case of short pulse durations. The distance of the electron
beam from the surface of the tube in vacuum is estimated on the basis of a one-dimensional model. It is shown that the electron
radiation can travel to a distance of several centimeters from the surface at current densities below 20 A/mm2, whereas at high current densities the beam is trapped near the surface.
Zh. Tekh. Fiz. 69, 111–115 (May 1999) 相似文献
11.
The feasibility of producing high-current, high-energy electron beams was studied for the application of nanosecond voltage pulses with amplitudes to 300 kV in accelerating gaps. The pressures of the gap gases (helium and nitrogen) measured from 10–1 torr to atmospheric. Experiments showed that the placement of two barriers in the accelerating gap significantly increased the electron beam current due to an increase in the burn time of the volume discharge under conditions involving significant over-voltage in the electrical field. Electron beams with energies of up to 250 keV and currents up to 260 A were obtained.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 7–9, February, 1992. 相似文献
12.
The feasibility of shock initiation in thin pentaerythritol tetranitrate (PETN) single crystals under the action of a pulsed high-current electron beam (0.25 MeV, 20 ns, 15 J/cm2) is shown experimentally. The real-time dynamic characteristics of crystal glow arising under the action of the electron beam and glow due to subsequent shock-wave-induced transformations are presented. A shock wave results from beam energy absorption and initiation of an exothermal chemical reaction in the irradiated layer. 相似文献
13.
Brower D. F. Kusse B. R. Meixel G. D. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1974,2(3):193-195
Two experimentally verified methods are presented for the injection of high-current relativistic electron beams (30 kA, 400 kV) into strong toroidal magnetic fields (1-8 kGauss). Injection is accomplished by contouring the current flow in the stalk of a field-emission cathode to perturb the flux lines only during beam generation. On conclusion of the emission process the perturbed lines can return to their original positions thereby trapping the beam. 相似文献
14.
15.
提出了一种新结构的高功率径向强流速调管振荡器,该器件利用折叠式同轴谐振腔的微波场与接近空间电荷限制电流的径向电子束强烈相互作用产生高功率微波。首先对这种器件的实现机理进行了初步的分析,提出了有间隙电压情况时的径向同轴间隙的空间电荷限制电流1维近似估计模型。分析表明:对于电子束直流接近但小于直流空间限制电流的径向速调管,当有调制间隙电压时,空间限制电流要小于无调制间隙电压情况下的直流空间限制电流,径向强流电子束电流接近和超过空间电荷限制电流时会出现强烈的调制。然后用PIC程序对其特性进行了粒子模拟,在二极管输入电压500 kV、电子束电流为30 kA条件下,最终得到了峰值功率6 GW、频率1.3 GHz的微波输出。 相似文献
16.
17.
A.?V.?Agafonov 《Physics of Particles and Nuclei Letters》2010,7(7):490-493
The results of a numerical simulation of the nonstationary processes in different charge-neutralization schemes of high-current electron beams and the results of a measurement of the beam parameters are presented. Most attention is paid to beams with a current higher than the limiting Alfven current. 相似文献
18.
Current and space-charge density distribution calculation is of great significance for numerical analysis and design of high-current electron guns and beams. When the electrons’ thermal initial velocities are taken into account, though there have been some numerical methods published, the calculation is very complicated. By introducing equivalent meridional potential and projection trajectory theory, the curvilinear axis trajectory equation for electrons neighboring to a central curved trajectory in rotationally symmetric electro-magnetic fields is derived in first- and second-order approximations. The evolution equation of the current density distribution of toroidal electron sub-beams is derived and it can be used to calculate the current and charge density distribution in electron beams and guns in iteration calculation. A compact numerical algorithm for calculating round high-current electron guns and beams was developed and related program was written as well. As examples, the evolution of the current density distribution of a Pierce gun and a periodic magnetic focusing high-current electron beam is simulated. This proves that this method is effective and practical. 相似文献
19.
C. Habfast H. Poth B. Seligmann A. Wolf J. Berger P. Blatt P. Hauck W. Meyer R. Neumann 《Applied physics. B, Lasers and optics》1987,44(2):87-92
First results are presented from an experiment scattering laser light from a relativistic electron beam. The 5 cm diameter continuous electron beam of 28 keV kinetic energy and 2.6 A current presents an electron gas of a density of 8×107 cm–3, from which 20 ns pulses of laser light (490 nm) were scattered at a repetition rate of 15 Hz and an average power of 20 mJ per pulse. The Doppler-shifted wavelength of photons backscattered under 180° was analysed with a Fabry-Perot interferometer. This technique provides, for the first time, a non-destructive measurement of the velocity distribution in an electron beam radially resolved in space. The results presented here comprise the direct measurement of the absolute electron energy and the degree of space-charge compensation in the electron beam. The determination of an upper bound of 10–2 for the ratio of longitudinal to transverse electron temperature implies the first direct measurement of a flattened velocity distribution. 相似文献
20.
The transition of a low-current discharge with a self-heated hollow cathode to a high-current discharge is studied, and stability conditions for the latter in the pulsed–periodic mode with a current of 0.1–1.0 kA, pulse width of 0.1–1.0 ms, and a pulse repetition rate of 0.1–1.0 kHz are determined. The thermal conditions of the hollow cathode are analyzed, and the conclusion is drawn that the emission current high density is due to pulsed self-heating of the cathode’s surface layer. Conditions for stable emission from a plasma cathode with a grid acting as a plasma boundary using such a discharge are found at low accelerating voltage (100–200 eV) and a gas pressure of 0.1–0.4 Pa. The density of the ion current from a plasma generated by a pulsed beam with a current of 100 A is found to reach 0.1 A/cm2. Probe diagnostics data for the emitting and beam plasmas in the electron source are presented, and a mechanism behind the instability of electron emission from the plasma is suggested on their basis. 相似文献