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1.
V. F. Tarasenko E. Kh. Baksht D. V. Beloplotov A. G. Burachenko M. I. Lomaev 《Plasma Physics Reports》2016,42(4):369-381
The amplitude?temporal characteristics of a supershort avalanche electron beam (SAEB) with an amplitude of up to 100 A, as well as of the breakdown voltage and discharge current, are studied experimentally with a picosecond time resolution. The waveforms of discharge and SAEB currents are synchronized with those of the voltage pulses. It is shown that the amplitude?temporal characteristics of the SAEB depend on the gap length and the designs of the gas diode and cathode. The mechanism for the generation of runaway electron beams in atmospheric-pressure gases is analyzed on the basis of the obtained experimental data. 相似文献
2.
Electric explosion of fine tungsten wires in vacuum 总被引:1,自引:0,他引:1
A. G. Rousskikh R. B. Baksht A. Yu. Labetskii V. I. Oreshkin A. V. Shishlov S. A. Chaikovskii 《Plasma Physics Reports》2004,30(11):944-952
A study is made of the breakdown of a fine wire during its electric explosion in vacuum. The problem of how the wire diameter, the rate of energy deposition in the wire, and the insulation of the electrode surface near the electrode-wire contact influence the wire explosion and the accompanying breakdown is investigated experimentally. The wire explosion was performed at a positive polarity of the high-voltage electrode. A current density growth rate of 6×1011–5×1016 A/(s cm2) is achieved. It is shown that the breakdown along a wire is similar in many respects to the gas breakdown. The insulation of the wire surface makes it possible to avoid breakdown and to increase the deposited energy to values sufficient for the wire sublimation. 相似文献
3.
E. Kh. Baksht A. G. Burachenko M. V. Erofeev V. F. Tarasenko 《Plasma Physics Reports》2014,40(5):404-411
Pulse-periodic generation of supershort avalanche electron beams (SAEBs) and X-ray emission in nitrogen, as well as the transition from a single-pulse mode to a pulse-periodic mode with a high repetition frequency, was studied experimentally. It is shown that, in the pulse-periodic mode, the full width at halfmaximum of the SAEB is larger and the decrease rate of the gap voltage is lower than those in the single-pulse mode. It is found that, when the front duration of the voltage pulse at a nitrogen pressure of 90 Torr decreases from 2.5 to 0.3 ns, the X-ray exposure dose in the pulse-periodic mode increases by more than one order of magnitude and the number of SAEB electrons also increases. It is shown that, in the pulse-periodic mode of a diffuse discharge, gas heating in the discharge gap results in a severalfold increase in the SAEB amplitude (the number of electrons in the beam). At a generator voltage of 25 kV, nitrogen pressure of 90 Torr, and pulse repetition frequency of 3.5 kHz, a runaway electron beam was detected behind the anode foil. 相似文献
4.
Properties of phenylalanine transfer ribonucleic acid with modified 3''-terminal end in protein biosynthesis using a rabbit reticulocyte cell-free system: effect of the replacement of cytidine residues from the CpCpA end of tRNA by 5-iodocytidine or 2-thiocytidine. 总被引:1,自引:1,他引:0
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E K Baksht A Gal N de Groot A A Hochberg M Sprinzl F Cramer 《Nucleic acids research》1977,4(7):2205-2212
Phe-tRNA Phe from yeast containing 2-thiocytidine or 5-iodocytidine in position 75 of the polynucleotide chain or Phe-tRNA Phe in which both positions 74 and 75 were substituted by 5-iodocytidine were investigated in the poly U-dependent polyphenylalanine synthesis on ribosomes from rabbit reticulocytes. Phe-tRNA Phe-Cps2CpA was nearly as active as the native Phe-tRNA Phe-CpCpA in the overall process. Phe-tRNA Phe-Cpi 5CpA as well as Phe-tRNA Phe-i5Cpi 5CpA were considerably less active than the native species. Investigation of individual steps of protein biosynthesis with these modified substrates revealed that the donor activity of peptidyl-tRNAs which contain 5-iodocytidine in their 3'-terminus is strongly imparied suggesting exacting structural requirements for the interaction of the CpCpA end of tRNA with the ribosomal P-site. 相似文献
5.
It was shown theoretically that the increase in the cathode emission current in a low-voltage cesium-hydrogen discharge to ≈10 A/cm2 leads to an increase in the electron temperature in the anode plasma to T e ≥ 1 eV. In this regime, the rate constant for the production of H? ions via dissociative electron attachment to vibrationally excited H2 molecules is close to its maximum value and the density of H? ions is maximal (about 1013 cm?3) in the anode plasma. 相似文献
6.
R. B. Baksht A. Yu. Labetsky A. G. Rousskikh A. V. Fedyunin A. V. Shishlov V. A. Kokshenev N. E. Kurmaev F. I. Fursov 《Plasma Physics Reports》2001,27(7):557-562
Experiments are reported on the implosion of structured loads with outer argon, krypton, and xenon gas puffs and an inner tungsten multiwire array. Experiments were carried out in the GIT-12 generator with a current of 2.6 MA and a current rise time of 270 ns. It is shown that the current successfully switches to the wire array only when the gas puff is sufficiently light. The total implosion time is 300 ns, and the implosion time of a wire array, determined from streak camera images, is 50–70 ns. It is suggested that the switching is efficient only when the active impedance of the gas puff is higher than the transitional resistance of the electrically exploded wires. 相似文献
7.
A. G. Rousskikh R. B. Baksht A. Yu. Labetsky A. V. Shishlov A. V. Fedyunin 《Plasma Physics Reports》2001,27(7):549-556
Experiments are reported on the implosion of argon double gas puffs in the GIT-12 current generator (T
fr=0.25 μs, I
m
=2.3 MA). The gas-puff medium was preionized by different methods. The experimental data provide evidence for a strong effect
of the initial conditions for the formation of the current-carrying shell on the implosion process. Emphasis is given to a
discussion of the following issues: the enhanced scatter in both the emission power and X-ray yield in the Ar K-lines, the
existence of a large number of current filaments, the uncertainty in the process by which the generator current is redistributed
among a progressively smaller number of current filaments, and the redistribution of the generator current between the inner
and outer gas-puff shells.
__________
Translated from Fizika Plazmy, Vol. 27, No. 7, 2001, pp. 584–591.
Original Russian Text Copyright ? 2001 by Rousskikh, Baksht, Labetsky, Shishlov, Fedyunin. 相似文献
8.
A. G. Russkikh R. B. Baksht A. Yu. Labetskiĭ P. R. Levashov S. I. Tkachenko K. V. Khishchenko A. V. Shishlov A. V. Fedyunin S. A. Chaĭkovskiĭ 《Plasma Physics Reports》2006,32(10):823-835
Results are presented from experiments on the explosion of 30.5-μm tungsten wires at a current density of up to 140 MA/cm2 and resistive-heating time of 40–100 ns. The experiments were performed both with and without preheating of wires and at different polarities of the high-voltage electrode. The effect of plasma production at the electrodes on the initiation of breakdown along the exploding wire was investigated by using a frame camera. It is shown that, when the polarity of the high-voltage electrode is positive, breakdown begins with the formation of a bright spot on the wire surface near the cathode, whereas at the negative polarity, breakdown begins with the formation of bright spots on the cathode surface. A comparative analysis of the main characteristics of wire explosions is performed. It is shown that preheating of the conductor increases the resistive-heating time and, accordingly, the energy deposited in the wire core. This effect takes place during explosions of both single wires and wire arrays. The evolution of the state of a metal during the explosion (including melting and evaporation) is studied by one-dimensional simulations by using a semiempirical equation of state describing the properties of tungsten over a wide range of parameters. 相似文献
9.
Plasma Physics Reports - Modeling of the pulse-periodic high-pressure cesium discharge on the basis of the radiative gas dynamic equations is executed. Calculation results of radial profiles of the... 相似文献
10.
V. F. Tarasenko E. Kh. Baksht A. G. Burachenko M. I. Lomaev 《Plasma Physics Reports》2017,43(7):792-795
Results are presented from experimental studies of elevated-pressure diffuse discharge in a highly nonuniform electric field. It is shown that, in discharges in nitrogen and air, the characteristic radiation (the K-line of nitrogen) is generated at the positive polarity of the electrode with a small curvature radius. X-ray bremsstrahlung from the anode was detected in a discharge in atmospheric-pressure air at a 12-kV amplitude of the incident voltage pulse. 相似文献