共查询到20条相似文献,搜索用时 31 毫秒
1.
A wide-aperture plasma source of low-energy electron beams on the basis of an electrically asymmetric reflex discharge is studied experimentally. The characteristic features of the generation of electron beams are investigated, and the boundaries of the generation regime are determined. The influence of the dimensions and shape of the discharge electrodes on the source characteristics is examined. A method for efficiently controlling the electron-beam current is proposed. 相似文献
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3.
Wong C.S. Ong C.S. Lee S. Choi P. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1992,20(4):405-409
The generation of prebreakdown electron beams in a low-energy vacuum spark with a hollow-cathode configuration is observed under a range of experimental conditions. The vacuum spark studied is powered by either a 25-kV, 3.3-nF single capacitor discharge or a two-stage, 50-kV, 1.65-nF Marx. The electron beams are detected by observing the X-ray emission from the anode tip produced by electron impact. Results show that an electron beam is formed well before the onset of the electrical breakdown. This prebreakdown electron beam has an initial slow buildup phase followed by an exponential rise, leading to the breakdown of the discharge. This behavior of the electron beam evolution is in good qualitative agreement with the model simulation of the pseudospark phenomenon obtained for a transient hollow-cathode discharge 相似文献
4.
Shunri Oda Kenji Akagi Hiroshi Kukimoto Tadahisa Nakayama 《Journal of luminescence》1978,16(3):323-330
Bright blue and green cathodoluminescence from low resistivity ZnS crystals has been observed under the excitation of low-energy electron beams of several tens of volts; i.e., 40 fL at 50 V. Properties of the surface of the crystals are studied by the dependence of current and brightness on applied voltage and by the spectra of cathodoluminescence and photoluminescence. 相似文献
5.
The process of formation of high-density low-energy (5–10 keV) pulsed electron beams of small diameter (on the order of a
few millimeters) in a gun of the “channel-spark” type is studied. It is shown that beams with a rate of rise of the current
exceeding 1011 A/s and an amplitude exceeding the Alfvén current by a factor of 1.5–2.0 can be obtained in experiments with intense preionisation
of the transport channel combined with a pulsed supply of the accelerating voltage to the cathode. In the optimal pressure
mode, the current density at a distance of 2–3 cm from the gun outlet is 40–25 kA/cm2, which will ensure ablation of most solid targets. 相似文献
6.
A model of thermal erosion of a metal surface under the action of low-energy fine-focused scanning electron beams is developed. Peculiarities of thermal erosion of a metal surface irradiated by these beams with a power of 1…10 kW are considered. The influence of the irradiation parameters on the intensity of carrying the substance from the surface is analyzed. It is shown that due to such beams, the coefficients of metal erosion reach values of 103 atom/electron and even greater. This is characteristic of powerful submicrosecond electron and ion beams, but the efficiency of using their energy turns out to be much higher. 相似文献
7.
A. Sirunyan A. Hakobyan G. Ayvazyan A. Babayan H. Vardanyan G. Zohrabyan K. Davtyan H. Torosyan A. Papyan 《Journal of Contemporary Physics (Armenian Academy of Sciences)》2018,53(4):271-278
Owing to the growing interest in the low-energy nuclear physics, it becomes relevant to enhance the potential of the experimental facilities at Yerevan Physics Institute (YerPhI). The complex unit based on the linear electron accelerator LUE-75 (ARUS synchrotron injector) for applied and fundamental experiments with electron beams, the intensity and energy of which can vary in a wide range of 10–18–10–5 А and 10–50 MeV, has been created. In recent years, the regimes developed at LUE-75 were applied to obtain the controllable electron beams of extremely low intensity used for calibration of detectors. 相似文献
8.
Favre M. Chuaqui H. Wyndham E.S. Choi P. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1992,20(2):53-56
Two different regimes of electron beams have been reported in the pulsed hollow cathode discharge-a low-current, high-energy beam, and a relatively high-current beam of low energy. The high-energy beam is related to the hollow cathode geometry and is found to be present even in the absence of subsequent gas breakdown, while the low-energy beam is always associated with voltage breakdown. Detailed measurements of the spatial and temporal distribution of the electron beam transported beyond a semitransparent anode associated with gas breakdown are reported. In particular, a high-energy component is observed after electrical breakdown. Low-energy electron beams are observed to be transported beyond the anode throughout the main discharge period 相似文献
9.
Two types of contracted arc discharge are investigated with a view to generating intense electron beams over a wide pressure range (1–10–3 Pa). For an arc discharge with a hollow cathode and anode, an electron beam corresponding to a current of up to 300 A and a pulse length of 25 µsec is obtained at a pressure of 1–10–1 Pa in the accelerating gap with an accelerating voltage of up to 15 kV. At pressures of 10–2–10–3 Pa, emitting plasma is created by a low-pressure arc discharge on the basis of a Penning cell. Three discharge systems operating in parallel are used to increase the working life of the cathode and improve the current density distribution of the beam. An electron beam of diameter 200 mm with a current of up to 125 A and a pulse length of 50 µsec is obtained.Institute of High-Power Electronics, Siberian Branch, Russian Academy of Sciences. Translated from Izvestiya Vysshkikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 76–82, March, 1994. 相似文献
10.
Works on the physics of electron runaway in gases, developing a new understanding of formation of runaway electron beams in
gas discharge, are reviewed. Results of experiments with atmospheric-pressure gas-filled diodes, in which subnanosecond electron
beams with a record current amplitude were obtained, are reported. The properties of volume nanosecond discharge, allowing
to obtain such beams, are analyzed. 相似文献
11.
H. Löhner B. Ludewigt D. Frekers G. Gaul R. Santo 《Zeitschrift für Physik A Hadrons and Nuclei》1979,290(1):35-41
On the basis of low pressure spark discharges a new type of a particle accelerator as been developed. It produces pulsed ion as well as electron beams of high intensities in a gas atmosphere at pressures of the order of 1 mbar. The method was used to produce in hydrogene at particle energies of about 70 keV an electron beam with a current density of more than 106 A/cm2 at 140 A total current. It is shown that magnetic confinement by the pinch effect takes place in the discharge. Discharge times smaller than 5 ns and spark frequencies up to 2 MHz can be obtained. 相似文献
12.
Bugaev S.P. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1991,19(5):743-745
At present, ion and electron beams, extensively used in industry, usually have a small cross section. Presented are generators of ion and electron flows with a large cross section using plasma emitters. These devices have a wide range of currents and voltages and are designed for metallurgical treatment and microelectronics. The author discusses a technological source of ions based on the vacuum-arc excited by a constricted discharge electron-beam installation with a large cross-section beam for microelectronics technology, a high-power electron-energy complex for heat treatment of manufactured articles and a generator of a low-energy, high-current electron beam with a plasma anode 相似文献
13.
An approach to the reconstruction of the electron energy distribution function (EEDF) as the sum of the second derivative of the electron current to the probe and some value proportional to its first derivative is proposed (hereafter we mean derivatives with respect to voltage). Solutions to model problems for typical electron distributions in a plasma show that this approach lowers the systematic error of EEDF reconstruction by several times in comparison with the conventional techniques using Langmuir and diffusion probes. The approach is applicable in a wide range of the ratio of the probe radius to the free path of electrons. It can be used for the determination of fast nonequilibrium electron distribution in neon discharge afterglow and also for the evaluation of the Maxwellian electron temperature in the low-energy range of nitrogen discharge afterglow. 相似文献
14.
Experimental data for the electrical and optical characteristics of a transverse slot-cathode nanosecond discharge are reported.
The discharge is initiated in He at a discharge current of 1–500 A and a working gas pressure in a discharge chamber ranging
from 102 to 104 Pa. It is shown that the cathode current density is much (several orders of magnitude) higher than the total current density
of an equivalent abnormal discharge. The electrical characteristics of an open discharge and a discharge confined by dielectric
walls are found to differ considerably. Electrons passing through the cathode fall region acquire a high energy (on the order
of 1 keV) under the given conditions. The fast electron relaxation conditions correlate with the initiation and evolution
of the discharge. A pattern of the discharge evolution is derived from experimental data. A way of estimating the coefficient
of electron emission from the cathode plasma is suggested. 相似文献
15.
Research has been done on major physical processes governing the scope for generating magnetized low-energy high-current electron beams in a plasma-filled system. Conditions are considered for efficient excitation of the explosive electron emission at a large-area cathode at low accelerating voltages, together with the trends in beam formation in the nonstationary double layer formed between the cathode and anode plasmas, as well as the beam transport to the collector in the inhomogeneous guiding plasma. It is found that a gun having a plasma anode enables one to generate wide-aperture electron beams of microsecond duration having a mean electron energy of 10–20 keV and an energy density of up to 20 J/cm2 or more, which goes with homogeneity sufficient for technological purposes.High-Current Electronics Institute, Siberian Branch, Russian Academy of Sciences. Translated from Izvestiya Vysshikh, Fizika, No. 3, pp. 100–114, March, 1994. 相似文献
16.
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
17.
Murray C.S. Rocca J.J. Szapiro B. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1988,16(5):570-573
A reflex electron beam glow discharge has been used as a plasma source for the generation of broad-area electron beams. An electron current of 120 A (12 A/cm2) was extracted from the plasma in 10 μs pulses and accelerated to energies greater than 1 keV in the gap between two grids. The scaling of the scheme for the generation of multikiloamp high-energy electron beams is discussed 相似文献
18.
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
19.
S. Schwarz C. Bachelet M. Block G. Bollen D. Davies M. Facina C. M. Folden III C. Guénaut J. Huikari E. Kwan A. A. Kwiatkowski D. J. Morrissey G. Pang A. Prinke R. Ringle J. Savory P. Schury C. Sumithrarachchi T. Sun 《Hyperfine Interactions》2006,173(1-3):113-122
The low-energy beam and ion trap facility LEBIT at the NSCL at MSU has demonstrated that rare isotopes produced by fast-beam
fragmentation can be slowed down and prepared such that precision experiments with low-energy beams are possible. For this
purpose high-pressure gas-stopping is employed combined with advanced ion manipulation techniques. Penning trap mass measurements
on short-lived rare isotopes have been performed with a 9.4 T Penning trap mass spectrometer. Examples include 66As, which has a half-live of only 96 ms, and the super-allowed Fermi-emitter 38Ca, for which a mass accuracy of 8 ppb (280 eV) has been achieved. The high accuracy of this new mass value makes 38Ca a new candidate for the test of the conserved vector current hypothesis.
相似文献
20.
The most popular methods for submicrosecond electron beam generation and physical processes underlying electron extraction from plasma in plasma emitters are considered. Electron sources and accelerators developed on the basis of plasma emitters allow pulsed beams with currents from tens to 103 A and current densities of several amperes per square centimeter, pulse durations of hundreds of nanoseconds, and high repetition rates to be generated. 相似文献