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Title: Fundamental properties of field emission-driven direct current microdischarges

Abstract

For half a century, it has been known that the onset of field emission in direct current microdischarges with gap sizes less than 10 {mu}m can lead to breakdown at applied voltages far less than predicted by Paschen's law. It is still unclear how field emission affects other fundamental plasma properties at this scale. In this work, a one-dimensional fluid model is used to predict basic scaling laws for fundamental properties including ion density, electric field due to space charge, and current-voltage relations in the pre-breakdown regime. Computational results are compared with approximate analytic solutions. It is shown that field emission provides an abundance of cathode electrons, which in turn create large ion concentrations through ionizing collisions well before Paschen's criterion for breakdown is met. Breakdown due to ion-enhanced field emission occurs when the electric field due to space charge becomes comparable to the applied electric field. Simple scaling analysis of the 1D Poisson equation demonstrates that an ion density of n{sub +} Almost-Equal-To 0.1V{sub A}{epsilon}{sub 0}/qd{sup 2} is necessary to significantly distort the electric field. Defining breakdown in terms of this critical ion density leads analytically to a simple, effective secondary emission coefficient {gamma}{sup Prime} of the same mathematicalmore » form initially suggested by Boyle and Kisliuk [Phys. Rev. 97, 255 (1955)].« less

Authors:
;  [1]
  1. Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, Indiana 46556 (United States)
Publication Date:
OSTI Identifier:
22089539
Resource Type:
Journal Article
Journal Name:
Journal of Applied Physics
Additional Journal Information:
Journal Volume: 112; Journal Issue: 10; Other Information: (c) 2012 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0021-8979
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ANALYTICAL SOLUTION; APPROXIMATIONS; BREAKDOWN; COLLISIONS; DIRECT CURRENT; ELECTRIC DISCHARGES; ELECTRIC FIELDS; ELECTRONS; FIELD EMISSION; ION DENSITY; ION EMISSION; PLASMA; PLASMA DENSITY; POISSON EQUATION; SCALING LAWS; SECONDARY EMISSION; SPACE CHARGE

Citation Formats

Rumbach, Paul, and Go, David B. Fundamental properties of field emission-driven direct current microdischarges. United States: N. p., 2012. Web. doi:10.1063/1.4764344.
Rumbach, Paul, & Go, David B. Fundamental properties of field emission-driven direct current microdischarges. United States. doi:10.1063/1.4764344.
Rumbach, Paul, and Go, David B. Thu . "Fundamental properties of field emission-driven direct current microdischarges". United States. doi:10.1063/1.4764344.
@article{osti_22089539,
title = {Fundamental properties of field emission-driven direct current microdischarges},
author = {Rumbach, Paul and Go, David B.},
abstractNote = {For half a century, it has been known that the onset of field emission in direct current microdischarges with gap sizes less than 10 {mu}m can lead to breakdown at applied voltages far less than predicted by Paschen's law. It is still unclear how field emission affects other fundamental plasma properties at this scale. In this work, a one-dimensional fluid model is used to predict basic scaling laws for fundamental properties including ion density, electric field due to space charge, and current-voltage relations in the pre-breakdown regime. Computational results are compared with approximate analytic solutions. It is shown that field emission provides an abundance of cathode electrons, which in turn create large ion concentrations through ionizing collisions well before Paschen's criterion for breakdown is met. Breakdown due to ion-enhanced field emission occurs when the electric field due to space charge becomes comparable to the applied electric field. Simple scaling analysis of the 1D Poisson equation demonstrates that an ion density of n{sub +} Almost-Equal-To 0.1V{sub A}{epsilon}{sub 0}/qd{sup 2} is necessary to significantly distort the electric field. Defining breakdown in terms of this critical ion density leads analytically to a simple, effective secondary emission coefficient {gamma}{sup Prime} of the same mathematical form initially suggested by Boyle and Kisliuk [Phys. Rev. 97, 255 (1955)].},
doi = {10.1063/1.4764344},
journal = {Journal of Applied Physics},
issn = {0021-8979},
number = 10,
volume = 112,
place = {United States},
year = {2012},
month = {11}
}