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Title: Computation of the effect of neutral collisions on ion current to a floating sphere in a stationary plasma

Abstract

The Specialized-Coordinate Electrostatic Particle and Thermals in Cell (SCEPTIC) code [I. H. Hutchinson, Plasma Physics and Controlled Fusion 45, 1447 (2003)] is used to compute the ion flux to a floating sphere in a stationary plasma, including the effects of charge-exchange collisions with neutrals. The results agree well with the available prior calculations at very low and very high collisionality thus validating the code and those prior calculations. In addition, SCEPTIC provides quantitative results at intermediate collisionalities where no analytic theory is available. Reasonable agreement in the floating potential is found there with some prior numerical results. For {lambda}{sub De} much greater than the sphere radius, enhancements of the ion collection above the orbital motion limited value by factors as high as 5 occur, enough to exceed slightly the radial motion value, but only over a restricted range of collisionality. An explicit analytic fit to SCEPTIC's results is provided for easy evaluation over the entire range of collisionality.

Authors:
;  [1]
  1. Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)
Publication Date:
OSTI Identifier:
20960126
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 14; Journal Issue: 1; Other Information: DOI: 10.1063/1.2431584; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; CALCULATION METHODS; CHARGE EXCHANGE; COLLISIONS; COORDINATES; CURRENTS; IONS; PLASMA; PLASMA SIMULATION; SPHERES

Citation Formats

Hutchinson, I. H., and Patacchini, L. Computation of the effect of neutral collisions on ion current to a floating sphere in a stationary plasma. United States: N. p., 2007. Web. doi:10.1063/1.2431584.
Hutchinson, I. H., & Patacchini, L. Computation of the effect of neutral collisions on ion current to a floating sphere in a stationary plasma. United States. doi:10.1063/1.2431584.
Hutchinson, I. H., and Patacchini, L. Mon . "Computation of the effect of neutral collisions on ion current to a floating sphere in a stationary plasma". United States. doi:10.1063/1.2431584.
@article{osti_20960126,
title = {Computation of the effect of neutral collisions on ion current to a floating sphere in a stationary plasma},
author = {Hutchinson, I. H. and Patacchini, L.},
abstractNote = {The Specialized-Coordinate Electrostatic Particle and Thermals in Cell (SCEPTIC) code [I. H. Hutchinson, Plasma Physics and Controlled Fusion 45, 1447 (2003)] is used to compute the ion flux to a floating sphere in a stationary plasma, including the effects of charge-exchange collisions with neutrals. The results agree well with the available prior calculations at very low and very high collisionality thus validating the code and those prior calculations. In addition, SCEPTIC provides quantitative results at intermediate collisionalities where no analytic theory is available. Reasonable agreement in the floating potential is found there with some prior numerical results. For {lambda}{sub De} much greater than the sphere radius, enhancements of the ion collection above the orbital motion limited value by factors as high as 5 occur, enough to exceed slightly the radial motion value, but only over a restricted range of collisionality. An explicit analytic fit to SCEPTIC's results is provided for easy evaluation over the entire range of collisionality.},
doi = {10.1063/1.2431584},
journal = {Physics of Plasmas},
number = 1,
volume = 14,
place = {United States},
year = {Mon Jan 15 00:00:00 EST 2007},
month = {Mon Jan 15 00:00:00 EST 2007}
}