共查询到20条相似文献,搜索用时 174 毫秒
1.
V. B. Bratchikov K. A. Gagarinov I. D. Kostyrya V. F. Tarasenko A. N. Tkachev S. I. Yakovlenko 《Technical Physics》2007,52(7):856-864
X-ray radiation from the volume discharge in atmospheric-pressure air is studied under the conditions when the voltage pulse rise time varies from 0.5 to 100 ns and the open-circuit voltage amplitude of the generator varies from 20 to 750 kV. It is shown that a volume discharge from a needle-like cathode forms at a relatively wide voltage pulse (to ≈60 ns in this work). The volume character of the discharge is due to preionization by fast electrons, which arise when the electric field concentrates at the cathode and in the discharge gap. As the voltage pulse rise time grows, X-ray radiation comes largely from the discharge gap in accordance with previous experiments. Propagation of fast avalanche electrons in nitrogen subjected to a nonuniform unsteady electric field is simulated. It is demonstrated that the amount of hard X-ray photons grows not only with increasing voltage amplitude but also with shortening pulse rise time. 相似文献
2.
Boichenko A. M. Burachenko A. G. Kostyrya I. D. Tarasenko V. F. Tkachev A. N. 《Technical Physics》2011,56(8):1202-1209
The influence of the voltage pulse rise time on the amplitude of a runaway electron beam and X-ray generation in air and nitrogen
under atmospheric pressure is studied experimentally and theoretically. Generalization of the whistle criterion for the case
of a nonuniform field is suggested. It is shown that the maximal energy of beam electrons and the beam current amplitude grow
when the voltage pulse rise time decreases. It is found that the amplitude of the runaway electron current reaches a maximum
at a certain curvature of the cathode. The maximal energy of electrons increases when the radius of curvature of the cathode
exceeds the value at which the beam current amplitude is the highest. If the field is nonuniform, its critical value at which
many electrons run away is more than an order of magnitude lower than in the uniform field. 相似文献
3.
V. F. Tarasenko 《Technical Physics》2007,52(4):534-536
The effect of the amplitude and rise time of a voltage pulse from a RADAN-303 pulser on the formation of an ultrashort avalanche electron beam (UAEB) in a gas diode is experimentally investigated. It is shown that, when the open-circuit voltage of the pulser exceeds an optimum value, the beam current amplitude and the gap voltage under which the UAEB is generated decrease. 相似文献
4.
E. Kh. Baksht A. G. Burachenko M. V. Erofeev M. I. Lomaev D. V. Rybka D. A. Sorokin V. F. Tarasenko 《Laser Physics》2008,18(6):732-737
A discharge in the presence of a nonuniform electric field and the generation of an ultrashort avalanche electron beam (UAEB) are studied in the insulating gas SF6 at the pressures 0.01–2.50 atm. High-voltage nanosecond pulses (about 150 and 250 kV) and the voltage pulses with an amplitude of 25 kV and a duration of tens of nanoseconds are applied across the gap. An electron beam is obtained behind the AlBe foil with a thickness of 45 μm at a sulfur hexafluoride pressure in a gas-filled diode of up to 2 atm. It is demonstrated that, at relatively high pressures (greater than 1 atm) and in the presence of high-voltage nanosecond pulses across the gap, the UAEB pulse FWHM increases. The spectra of the diffuse and contracted discharges in sulfur hexafluoride are measured. 相似文献
5.
I. D. Kostyrya V. M. Orlovskiĭ V. F. Tarasenko A. N. Tkachev S. I. Yakovlenko 《Technical Physics》2005,50(7):881-885
A study is made of the formation of a volume discharge in atmospheric-pressure air in a nonuniform electric field without additional preionization. It is shown that the spatial distribution of the plasma glow between a plane and a spherical (as well as a point) electrode at a subnanosecond rise time of the high-voltage pulse is volumetric in character. The change of the voltage polarity does not qualitatively affect the character of the glow. The propagation of a spherical ionization wave in nitrogen is calculated in the drift-diffusion approximation. The fact that the character of the discharge glow is essentially independent of the voltage polarity is explained by the multiplication of the background electrons in the dense working gas. 相似文献
6.
A. M. Boichenko V. F. Tarasenko E. Kh. Baksht A. G. Burachenko M. V. Erofeev A. N. Tkachev 《Technical Physics》2013,58(3):370-374
The influence of the nitrogen pressure on the breakdown voltage in a nonuniform electric field is studied. Voltage pulses with nanosecond and subnanosecond rise times are applied to the gas gap. Simultaneously with the application of voltage pulses, supershort avalanche electron beam pulses are observed behind a foil anode. It is found that, when a runaway electron beam is generated and voltage pulses have a subnano-second rise time, the breakdown voltage rises as the nitrogen pressure decreases from 9 × 104 to 1 × 102 Pa. Experimental data are in good agreement with pulsed breakdown analytical curves. 相似文献
7.
V. F. Tarasenko S. B. Alekseev V. M. Orlovskii V. G. Shpak S. A. Shunailov 《Technical Physics》2004,49(8):982-986
Conditions are studied under which an electron beam and a volume discharge with a subnanosecond rise time of a voltage pulse
are produced in air under atmospheric pressure. It is shown that the electron beam appears in a gas-filled diode at the front
of the voltage pulse in ∼0.5 ns, has a half-intensity duration of ≤0.4 ns and an average electron energy of ∼0.6 of the voltage
across the gas-filled diode, and terminates when the voltage across the gap reaches its maximum value. The electron beam with
an average electron energy of 60 to 80 keV and a current amplitude of ≥70 A is obtained. It is assumed that the electron beam
is formed from electrons produced in the gap due to gas ionization by fast electrons when the intensity of the field between
the front of the expanding plasma cloud and the anode reaches its critical value. A nanosecond volume discharge with a specific
power input of ≥400 MW/cm3, a density of the discharge current at the anode of up to 3 kA/cm2, and specific energy deposition of ∼1 J/cm3 over 3 to 5 ns is created. 相似文献
8.
E. H. Baksht A. G. Burachenko M. V. Erofeev I. D. Kostyrya M. I. Lomaev D. V. Rybka V. F. Tarasenko 《Technical Physics》2008,53(6):804-807
The effect of a transverse magnetic field (0.080 and 0.016 T) on generation of an electron beam in the gas-filled diode is
experimentally investigated. It is shown that, at voltage U = 25 kV across the diode and a low helium pressure (45 Torr), the transverse magnetic field influences the beam current amplitude
behind a foil and its distribution over the foil cross section. At elevated pressures and under the conditions of ultrashort
avalanche electron beam formation in helium, nitrogen, and air, the transverse magnetic field (0.080 and 0.016 T) has a minor
effect on the amplitude and duration of the beam behind the foil. It is established that, when the voltage of the pulse generator
reaches several hundreds of kilovolts, some runaway electrons (including the electrons from the discharge plasma near the
cathode) are incident on the side walls of the diode. 相似文献
9.
E. Kh. Baksht I. D. Kostyrya M. I. Lomaev D. V. Rybka V. F. Tarasenko 《Physics of Wave Phenomena》2008,16(3):199-206
The results of experimental study on generation of ultrashort avalanche electron beams (UAEB) in gas-filled diodes are considered.
The spatial distribution of the flux of runaway electrons and X-rays generated in the gas diode fed by nanosecond high-voltage
pulses was studied. It was shown that the UAEB in the gas-filled diode (at an air pressure of 1 atm) with sharply nonuniform
electric field is generated from the interelectrode region into a solid angle exceeding 2π sr. Narrowing of the cathode-anode
gap results in a decrease in the current amplitude of the beam generated to side walls of the gas diode and an increase in
the beam current pulse duration in both axial and radial directions. Current pulses of the beam initiated from the side surface
of the tubular cathode were detected. 相似文献
10.
E. H. Baksht A. G. Burachenko A. V. Kozyrev I. D. Kostyrya M. I. Lomaev V. K. Petin D. V. Rybka V. F. Tarasenko S. V. Shljakhtun 《Technical Physics》2009,54(1):47-55
The spectra of electrons and X-ray photons generated in nanosecond discharges in air under atmospheric pressure are investigated
theoretically and experimentally. Data for the discharge formation dynamics in a nonuniform electric field are gathered. It
is confirmed that voltage pulses with an amplitude of more than 100 kV and a rise time of 1 ns or less causing breakdown of
an electrode gap with a small-radius cathode generate runaway electrons, which can be divided into three groups in energy
(their energy varies from several kiloelectronvolts to several hundreds of kiloelectronvolts). It is also borne out that the
formation of the space charge is due to electrons appearing in the gap at the cathode and a major contribution to the electron
beam behind the foil comes from electrons of the second group, the maximal energy of which roughly corresponds to the voltage
across the gap during electron beam generation. X-ray radiation from the gas-filled diode results from beam electron slowdown
both in the anode and in the gap. It is shown that the amount of group-3 electrons with an energy above the energy gained
by runaway electrons (in the absence of losses) at a maximal voltage across the gap is much smaller than the amount of group-2
electrons. 相似文献
11.
An analysis of modern notions of breakdown in condensed media opens up new possibilities for a decrease in the microsecond
voltages for solid dielectric breakdown. Investigations of solid dielectric and rock breakdowns on the trailing edge of a
voltage pulse in a sharply nonuniform field demonstrate that the pulse amplitude and the slope of the working voltage pulse
edge can be decreased significantly. 相似文献
12.
E. H. Baksht I. D. Kostyrya E. I. Lipatov M. I. Lomaev D. V. Rybka V. F. Tarasenko 《Technical Physics》2007,52(4):489-494
The characteristics of an IMA3-150É sealed-off vacuum diode connected to a RADAN-220 nanosecond pulser are investigated. It is found that the electron beam behind the foil contains electrons with an energy exceeding the voltage applied to the diode. It is shown that the elevated-energy electrons appear at the leading edge of a current pulse, the FWHM of the current pulse of these electrons is 200–450 ps, and the pulse amplitude reaches several tens of amperes. 相似文献
13.
Nanosecond space discharge in a gas-filled diode is promising for pumping of lasers and high-power lamps. The space charge formed in the absence of an additional preionization source has a few advantages. The energy distributions of the beam electrons and the X-ray spectrum are determined. It is demonstrated that several high-energy electron bunches are formed in such a discharge. The main contribution to the beam current measured behind the foil is related to the runaway electrons, which have energies of tens or hundreds of kiloelectronvolts (supershort avalanche electron beam (SAEB)). Fast electrons with energies of several or tens of kiloelectronvolts are responsible for the generation of the soft X rays in the discharge gap. Anomalous electrons whose energy is higher than the voltage across the gap provide for a minor (less than 5%) contribution to the beam current. The generation time of these electrons is equal to the SAEB generation time accurate to 0.1 ns. It is demonstrated that the anomalous electrons can be generated owing to the acceleration in the presence of the field in front of the moving background-electron multiplication wave. The spectra of the X-ray radiation generated by the fast electrons in the volume are calculated. 相似文献
14.
V. F. Tarasenko I. D. Kostyrya V. K. Petin S. V. Shlyakhtun 《Technical Physics》2006,51(12):1576-1585
The energy distributions of beam electrons and x-ray photons in a volume nanosecond discharge on atmospheric-pressure air are studied. Several groups of elevated-energy electrons are found. It is shown that electrons with an energy from several tens to several hundreds of kiloelectronvolts (which is lower than a maximal voltage across the gap) make a major contribution to the beam current measured behind thin foils. It is corroborated that fast electrons (with an energy from several kiloelectronvolts to several tens of kiloelectron-volts) arise 100–150 ps before the basic peak of the beam current, elongating the current pulse and significantly increasing its amplitude. The contribution from electrons with an anomalously high energy (exceeding a maximal voltage across the gap) to the beam current is shown to be insignificant (less than 5%). The x-ray spectra in gas-filled diodes of different design are studied. Techniques of measuring the subnanosecond electron beam current and mechanisms generating fast and runaway electrons in volume high-pressure gas discharges are analyzed. 相似文献
15.
E. Kh. Baksht V. F. Tarasenko M. I. Lomaev D. V. Rybka A. N. Tkachev S. I. Yakovlenko 《Laser Physics》2007,17(9):1124-1128
The generation of the runaway-electron beam in nitrogen and helium is studied at an oscillator voltage of about 25 kV. Various regimes of the electron beam generation with a pulse duration ranging from 200 ps to several nanoseconds are realized depending on the pressure in the gas diode. An ultrashort avalanche electron beam (UAEB) with a low (10–20%) variation in the voltage across the gap is obtained at a relatively high pressure in the gas diode. The UAEB generation can be delayed relative to the leading edge of the voltage pulse by tens of nanoseconds at low oscillator voltages. 相似文献
16.
S. I. Yakovlenko 《Laser Physics》2007,17(3):268-281
It is demonstrated that the similarity relationships (breakdown curves), which establish a dependence of the field strength divided by the pressure on the product of the pressure and the delay time of the breakdown, are realized upon the uniform breakdown of the gas gap in the presence of both rectangular and triangular voltage pulses, which is interesting for the physics of gas and plasma discharges, and remain valid for strong fields. The breakdown criterion is described with a two-valued curve such that the effective multiplication of electrons in gas becomes possible in the presence of both weak and strong fields and at small products of the pressure and the pulse time. An analogue of the Stoletov effect, which corresponds to a maximum in the current with respect to pressure at a given voltage pulse, is demonstrated for the pulsed discharge. The analogues of the Stoletov constant are calculated for non-self-sustained pulsed discharges in various gases. The minimum delay time of the breakdown is also determined by these constants. 相似文献
17.
18.
Morrow R. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1991,19(2):86-94
A theoretical examination is made of the mechanism of corona formation for a positive point-plane gap in SF6 at 100 kPa. The impulse voltage applied has a rise time of 15 ns and peak value of 200 kV. Seed electrons are released 1 ns after the start of the voltage rise. For a 0.5-cm diameter positive sphere located 6.5 cm from a negative plane, the calculated circuit current initially consists of subnanosecond corona onset pulses, and then the current steadily rises to a maximum, as the voltage reaches a maximum, followed by a rapid fall in current. During the current rise a streamer moves out into the gap along a 100-μm channel, with the electric field in the streamer trail E>E*, where E* is the critical field where ionization equals attachment. The light output during the discharge is predicted to be a maximum at the anode with only a minor pulse of light at the streamer head, making it hard to detect. After the current maximum, recombination rapidly reduces the numbers of positive ions, negative ions, and electrons, but the net charge density remains constant and thus so does the electric field. The electric field is E~E* in the streamer trail, but has a sharp maximum, E≫E* at the head of the streamer trail. The origin of mid-gap precursors, observed when the streamer channel reilluminates after some 100 ns, is attributed to this field maximum in the remnant electric field. The evolution of positive ions, negative ions, and electrons is described by one-dimensional continuity equations, with the space-charge electric fields determined by the disk method. The effects of ionization, attachment, recombination, electron diffusion, and photoionization are all included. New numerical methods allow resolution of the streamer head and the anode fall region to be obtained with a 1-μm mesh, while following the streamer propagation for ~2 cm 相似文献
19.
Sumeruk HA Kneip S Symes DR Churina IV Belolipetski AV Donnelly TD Ditmire T 《Physical review letters》2007,98(4):045001
Irradiation of a planar solid by an intense laser pulse leads to fast electron acceleration and hard x-ray production. We have investigated whether this high field production of fast electrons can be controlled by introducing dielectric spheres of well-defined size on the target surface. We find that the presence of spheres with a diameter slightly larger than half the laser wavelength leads to Mie enhancements of the laser field which, accompanied by multipass stochastic heating of the electrons, leads to significantly enhanced hard x-ray yield and temperature. 相似文献
20.
通过气体放电产生更高浓度的低温等离子体要求具有纳秒上升沿和纳秒脉宽的高重频快脉冲,而目前被广泛使用的MOSFET和IGBT都无法满足这些参数要求,而双极结型晶体管(BJT)的集电极与发射极之间的雪崩击穿过程具有快导通、快恢复、高稳定性等优点,适合作为小型Marx发生器的自击穿开关。文中对用多种型号的BJT进行击穿特性比较测试实验,发现可以通过改变BJT的门极和发射极的并联电阻来调节其雪崩击穿电压,实现一定范围的工作电压。雪崩击穿恢复特性实验表明,当击穿电流衰减到低于维持电流时,BJT就会开始恢复绝缘而关断,通过改变电路中的参数以控制击穿电流的变化就可以控制BJT的雪崩击穿导通时间(即导通脉宽)。将这些结论应用到实际电路中,可获得上升沿5 ns、脉宽为10 ns、幅值2 kV、重复频率高达100 kHz的纳秒快脉冲,可用于激发高浓度低温等离子体。 相似文献