skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Formation of a strong electric field resulting in the excitation of microplasma discharges at the edge of a dielectric film on a metal in a plasma flow

Abstract

Results are presented from experimental and analytical studies of the processes resulting in the excitation of microplasma discharges (MPDs) on a metal surface partially covered with a thin dielectric film under the action of an external plasma flow in vacuum. It is shown experimentally that MPDs are excited at the interface between the open metal surface and the region covered by the dielectric film. The probability of MPD excitation is investigated as a function of the thickness of the dielectric film deposited on the metal. It is found that, for a film thickness of 1 μm, the probability of MPD excitation is close to unity. As the film thickness decreases below ~10 nm or increases above ~10 μm, the probability of MPD excitation is reduced by more than two orders of magnitude. A two-dimensional kinetic numerical code is developed that allows one to model the processes of Debye sheath formation and generation of a strong electric field near the edge of a finite-thickness dielectric film on a metal surface in a plasma flow for different configurations of the film edge. It is shown that the maximum value of the tangential component of the electric field is reached at the filmmore » edge and amounts to E{sub max} ≈ |φ{sub 0}|/2d (where φ{sub 0} < 0 is the electric potential applied to the metal and d is the film thickness), which for typical conditions of experiments on the excitation of MPDs on metal surfaces (φ{sub 0} ≈–400 V, d ≈ 1 μm) yields E{sub max} ≈ 2 MV/cm. The results of kinetic simulations confirm the qualitative idea about the mechanism of the formation of a strong electric field resulting in the excitation of MPDs at the edge of a dielectric film on a metal surface in a plasma flow and agree with experimental data.« less

Authors:
; ;  [1]
  1. Russian Academy of Sciences, Prokhorov General Physics Institute (Russian Federation)
Publication Date:
OSTI Identifier:
22614113
Resource Type:
Journal Article
Resource Relation:
Journal Name: Plasma Physics Reports; Journal Volume: 42; Journal Issue: 6; Other Information: Copyright (c) 2016 Pleiades Publishing, Ltd.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; COMPUTER CODES; DIELECTRIC MATERIALS; ELECTRIC DISCHARGES; ELECTRIC FIELDS; ELECTRIC POTENTIAL; EXCITATION; EXPERIMENTAL DATA; KINETIC EQUATIONS; METALS; PLASMA; THICKNESS; THIN FILMS; TWO-DIMENSIONAL CALCULATIONS

Citation Formats

Ivanov, V. A., E-mail: ivanov@fpl.gpi.ru, Sakharov, A. S., and Konyzhev, M. E. Formation of a strong electric field resulting in the excitation of microplasma discharges at the edge of a dielectric film on a metal in a plasma flow. United States: N. p., 2016. Web. doi:10.1134/S1063780X16060039.
Ivanov, V. A., E-mail: ivanov@fpl.gpi.ru, Sakharov, A. S., & Konyzhev, M. E. Formation of a strong electric field resulting in the excitation of microplasma discharges at the edge of a dielectric film on a metal in a plasma flow. United States. doi:10.1134/S1063780X16060039.
Ivanov, V. A., E-mail: ivanov@fpl.gpi.ru, Sakharov, A. S., and Konyzhev, M. E. 2016. "Formation of a strong electric field resulting in the excitation of microplasma discharges at the edge of a dielectric film on a metal in a plasma flow". United States. doi:10.1134/S1063780X16060039.
@article{osti_22614113,
title = {Formation of a strong electric field resulting in the excitation of microplasma discharges at the edge of a dielectric film on a metal in a plasma flow},
author = {Ivanov, V. A., E-mail: ivanov@fpl.gpi.ru and Sakharov, A. S. and Konyzhev, M. E.},
abstractNote = {Results are presented from experimental and analytical studies of the processes resulting in the excitation of microplasma discharges (MPDs) on a metal surface partially covered with a thin dielectric film under the action of an external plasma flow in vacuum. It is shown experimentally that MPDs are excited at the interface between the open metal surface and the region covered by the dielectric film. The probability of MPD excitation is investigated as a function of the thickness of the dielectric film deposited on the metal. It is found that, for a film thickness of 1 μm, the probability of MPD excitation is close to unity. As the film thickness decreases below ~10 nm or increases above ~10 μm, the probability of MPD excitation is reduced by more than two orders of magnitude. A two-dimensional kinetic numerical code is developed that allows one to model the processes of Debye sheath formation and generation of a strong electric field near the edge of a finite-thickness dielectric film on a metal surface in a plasma flow for different configurations of the film edge. It is shown that the maximum value of the tangential component of the electric field is reached at the film edge and amounts to E{sub max} ≈ |φ{sub 0}|/2d (where φ{sub 0} < 0 is the electric potential applied to the metal and d is the film thickness), which for typical conditions of experiments on the excitation of MPDs on metal surfaces (φ{sub 0} ≈–400 V, d ≈ 1 μm) yields E{sub max} ≈ 2 MV/cm. The results of kinetic simulations confirm the qualitative idea about the mechanism of the formation of a strong electric field resulting in the excitation of MPDs at the edge of a dielectric film on a metal surface in a plasma flow and agree with experimental data.},
doi = {10.1134/S1063780X16060039},
journal = {Plasma Physics Reports},
number = 6,
volume = 42,
place = {United States},
year = 2016,
month = 6
}
  • Excitation of microplasma discharges in the interaction of a plasma flow with a metal surface partially covered with a dielectric film is investigated experimentally and theoretically. A new phenomenon-the excitation of microplasma discharges at the boundary between the free metal surface and the area covered with the film-is discovered. Microplasma discharges at the edge of the dielectric film are initiated by a strong electric field that arises between the free metal surface and the outer surface of the film in the interaction with the plasma flow. This field gives rise to surface breakdowns at the film edge, followed by themore » development of primary microplasma discharges. In turn, the dense plasma of primary microplasma discharges causes secondary microplasma discharges, which also arise at the edge of the dielectric film after the external plasma flow has already terminated. Microplasma discharges gradually evaporate the dielectric film, and the surface cleaned of the film acquires a microrelief due to the local melting and subsequent fast cooling of the metal at the sites of microplasma discharges.« less
  • Excitation of microplasma discharges in the interaction of a plasma flow with a metal surface partially covered with a dielectric film is investigated experimentally and theoretically. A new phenomenon-the excitation of microplasma discharges at the boundary between the free metal surface and the area covered with the film-is discovered. Microplasma discharges at the edge of the dielectric film are initiated by a strong electric field that arises between the free metal surface and the outer surface of the film in the interaction with the plasma flow. This field gives rise to surface breakdowns at the film edge, followed by themore » development of primary microplasma discharges. In turn, the dense plasma of primary microplasma discharges causes secondary microplasma discharges, which also arise at the edge of the dielectric film after the external plasma flow has already terminated. Microplasma discharges gradually evaporate the dielectric film, and the surface cleaned of the film acquires a microrelief due to the local melting and subsequent fast cooling of the metal at the sites of microplasma discharges.« less
  • The ultrafast dynamics of microplasmas generated by femtosecond laser pulses in noble gases has been investigated using four-wave mixing (FWM). The time dependence of the FWM signal is observed to reach higher intensity levels faster for Xe, with progressively lower scattering intensity and longer time dynamics for the noble gas series Xe, Kr, Ar, Ne, and He. The temporal dynamics is interpreted in terms of a tunnel ionization and impact cooling mechanism. A formalism to interpret the observed phenomena is presented here with comparison to the measured laser intensity and gas pressure trends.
  • Excitation of Al/Al{sub 2}O{sub 3} microplasma devices with 50 {mu}s, 800 V pulses produces, in Ar/H{sub 2} gas mixtures at 600 Torr, {approx}6 A current pulses with a duration of {approx}30 ns. Corresponding to peak current and power densities of {approx}10{sup 4} A/cm{sup 2} and {approx}2.5 GW/cm{sup 3}, respectively, these pulses are generated in a 10 {mu}s burst in which the voltage self-pulses at a repetition frequency of {approx}3 MHz. Analysis of the H{sub {alpha}}, H{sub {beta}}, and Ar II emission line profiles yields a plasma density of {approx}10{sup 17} cm{sup -3}, and the emission of O IV ions suggestsmore » the presence of energetic electrons. Images of the microplasma indicate that the plasma is initiated by surface flashover and extends {approx}200 {mu}m outside the microcavity.« less