Sergey B. Alekseev
Russian Academy of Sciences
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Featured researches published by Sergey B. Alekseev.
Laser and Particle Beams | 2004
V. F. Tarasenko; V. S. Skakun; I. D. Kostyrya; Sergey B. Alekseev; V. M. Orlovskii
This article reports on experimental studies of subnanosecond electron beams formed in air under atmospheric pressure. An electron beam with an amplitude of ∼170 A with a duration at FWHM of ∼0.3 ns has been obtained. Based on beam temporal characteristics and discharge spatial characteristics, the critical fields were supposed to be reached at plasma approach to anode. Simultaneously, the sharp high-energy pulse of e-beam current is generated. Of critical importance is the cathode type and occurrence on the cathode of plasma protrusions. It is shown that to get maximum amplitude of the electron beam in the gas diode, the discharge in the gas diode should be volumetric.
Technical Physics Letters | 2003
Sergey B. Alekseev; V. M. Orlovskii; V. F. Tarasenko
We have studied the electron beam formation in a diode filled with a molecular gas at atmospheric pressure. A beam current amplitude of up to ∼20 A at an electron energy of ∼70 keV was obtained in an air-filled diode. It is suggested that the main fraction of runaway electrons at low initial values of the parameter E/p (∼0.1 kV/(cm Torr)) is formed in the space between cathode plasma and anode. As the plasma spreads from cathode to anode, the electric field strength between the plasma front and anode increases and the E/p value reaches a critical level.
Technical Physics Letters | 2005
E. I. Lipatov; V. F. Tarasenko; V. M. Orlovskii; Sergey B. Alekseev; D. V. Rybka
Subnanosecond avalanche electron beams formed in air at atmospheric pressure ensure intense luminescence of synthetic ruby and natural spodumene crystals.
Technical Physics Letters | 2003
Sergey B. Alekseev; V. M. Orlovskii; V. F. Tarasenko; A. N. Tkachev; S. I. Yakovlenko
The formation of a beam of runaway electrons in a diode filled with helium at a pressure from 0.1 to 760 Torr was studied under conditions of a pulsed ≈4 ns) high ≈200 kV) voltage applied to the discharge gap. Both theoretical results and experimental data indicate that the electron beam is generated both at a large strength of the electric field, when the fraction of runaway electrons is large, and in a field of low strength, where intensive electron multiplication takes place. In the latter case, a high current can be obtained despite a small fraction of runaway electrons relative to their total number. The electron beams obtained in the helium-filled diode had a current amplitude of up to 140 A (corresponding to a current density above 10 A/cm2) at an electron energy of ∼150 keV.
Technical Physics | 2005
Sergey B. Alekseev; V. M. Orlovskii; V. F. Tarasenko; A. N. Tkachev; S. I. Yakovlenko
Electron beam formation in krypton, neon, helium, and nitrogen at elevated pressures are experimentally investigated. It is shown that, when the krypton, neon, and helium pressures are varied, respectively, from 70 to 760 Torr, from 150 to 760 Torr, and from 300 to 4560 Torr, runaway electrons are beamed at the instant the plasma in the discharge gap approaches the anode and the nonlocal criterion for electron runaway is fulfilled. The fast-electron simulation of discharge gap preionization is performed. The simulation data demonstrate that preionization in the discharge gap is provided if the voltage pulse rise time is shorter than a nanosecond under atmospheric pressure.
Technical Physics Letters | 2004
Sergey B. Alekseev; V. P. Gubanov; V. M. Orlovskii; V. F. Tarasenko
Subnanosecond electron beams can be formed in gas-filled diodes at high pressures (up to 6 and 4 bar in helium and nitrogen, respectively). In a diode filled with air at atmospheric pressure, a beam current amplitude above 240 A was obtained at a pulse duration (FWHM) of ∼0.2 s and a beam current density of ∼40 A/cm2.
Instruments and Experimental Techniques | 2003
Sergey B. Alekseev; V. P. Gubanov; V. M. Orlovskii; A. S. Stepchenko; V. F. Tarasenko
A technique for determining the amplitude and time parameters of pulsed electron beams is proposed. Using this technique, it is possible to measure weak currents. It is based on the non-self-sustained discharge initiated by the electron beam under investigation. The experimental results are presented for two electron beams formed in a gas-filled diode at the atmospheric pressure of air, nitrogen, a mixture of CO2 : N2 : He = 1 : 1 : 3, or helium and ejected through a foil or grid.
Instruments and Experimental Techniques | 2006
Sergey B. Alekseev; V. A. Kuvshinov; A. A. Lisenko; Mikhail I. Lomaev; V. M. Orlovskii; V. A. Panarin; E. A. Rozhdestvenskii; V. S. Skakun; V. F. Tarasenko
A photoreactor developed on the basis of a Xe2 excilamp with a power of ∼10 W (with a power density of 15 mW/cm2 emitted from a surface of ∼700 cm2), which can operate in liquids and gases at a pressure of up to 40 atm, and a multifunctional cell with an active volume of ∼760 cm3 is described. Data on water photolysis in a natural gas exposed to VUV radiation with λ=172 nm are presented.
Technical Physics | 2004
V. F. Tarasenko; Sergey B. Alekseev; V. M. Orlovskii; V. G. Shpak; S. A. Shunailov
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.
Technical Physics | 2012
Sergey B. Alekseev; E. Kh. Baksht; A. M. Boichenko; I. D. Kostyrya; V. F. Tarasenko; A. N. Tkachev
The dependences of the electron beam intensity and X-ray dose on the thickness of metal foils (Al, Cu) in a nanosecond discharge initiated in atmospheric-pressure air are studied theoretically and experimentally. Calculated curves of electron beam attenuation in aluminum and X-ray dose attenuation in copper agree well with experimental data. It is found that the amplitude of a super-short avalanche electron beam and the X-ray exposure dose reach maximal values at different values of the interelectrode gap. When the length of the cathode’s edge with a small radius of curvature increases, an interelectrode gap maximizing the amplitude of the runaway electron current shrinks.