Bohmcriterion approximation versus optimal matched solution for a cylindrical probe in radialmotion theory
Abstract
The theory of positiveion collection by a probe immersed in a lowpressure plasma was reviewed and extended by Allen et al. [Proc. Phys. Soc. 70, 297 (1957)]. The numerical computations for cylindrical and spherical probes in a sheath region were presented by F. F. Chen [J. Nucl. Energy C 7, 41 (1965)]. Here, in this paper, the sheath and presheath solutions for a cylindrical probe are matched through a numerical matching procedure to yield “matched” potential profile or “M solution.” The solution based on the Bohm criterion approach “B solution” is discussed for this particular problem. The comparison of cylindrical probe characteristics obtained from the correct potential profile (M solution) and the approximated Bohmcriterion approach are different. This raises questions about the correctness of cylindrical probe theories relying only on the Bohmcriterion approach. Also the comparison between theoretical and experimental ion current characteristics shows that in an argon plasma the ions motion towards the probe is almost radial.
 Authors:
 Theoretical Physics Division, PINSTECH, P. O. Nilore, 44000 Islamabad (Pakistan)
 Publication Date:
 OSTI Identifier:
 22599950
 Resource Type:
 Journal Article
 Resource Relation:
 Journal Name: Physics of Plasmas; Journal Volume: 23; Journal Issue: 8; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ARGON; BOHM CRITERION; CATIONS; COMPARATIVE EVALUATIONS; CYLINDRICAL CONFIGURATION; PLASMA PRESSURE; PROBES; SPHERICAL CONFIGURATION
Citation Formats
Din, Alif. Bohmcriterion approximation versus optimal matched solution for a cylindrical probe in radialmotion theory. United States: N. p., 2016.
Web. doi:10.1063/1.4960319.
Din, Alif. Bohmcriterion approximation versus optimal matched solution for a cylindrical probe in radialmotion theory. United States. doi:10.1063/1.4960319.
Din, Alif. 2016.
"Bohmcriterion approximation versus optimal matched solution for a cylindrical probe in radialmotion theory". United States.
doi:10.1063/1.4960319.
@article{osti_22599950,
title = {Bohmcriterion approximation versus optimal matched solution for a cylindrical probe in radialmotion theory},
author = {Din, Alif},
abstractNote = {The theory of positiveion collection by a probe immersed in a lowpressure plasma was reviewed and extended by Allen et al. [Proc. Phys. Soc. 70, 297 (1957)]. The numerical computations for cylindrical and spherical probes in a sheath region were presented by F. F. Chen [J. Nucl. Energy C 7, 41 (1965)]. Here, in this paper, the sheath and presheath solutions for a cylindrical probe are matched through a numerical matching procedure to yield “matched” potential profile or “M solution.” The solution based on the Bohm criterion approach “B solution” is discussed for this particular problem. The comparison of cylindrical probe characteristics obtained from the correct potential profile (M solution) and the approximated Bohmcriterion approach are different. This raises questions about the correctness of cylindrical probe theories relying only on the Bohmcriterion approach. Also the comparison between theoretical and experimental ion current characteristics shows that in an argon plasma the ions motion towards the probe is almost radial.},
doi = {10.1063/1.4960319},
journal = {Physics of Plasmas},
number = 8,
volume = 23,
place = {United States},
year = 2016,
month = 8
}

The theory of positiveion collection by a probe immersed in a lowpressure plasma was reviewed and extended by Allen, Boyd, and Reynolds [Proc. Phys. Soc. 70, 297 (1957)]. For a given value of the ion current, the boundary values of the matched “nonneutral” or “sheath” solution V{sup ~}{sub nn}{sup (m)}(r; r{sub m}) were obtained from the “quasineutral” or “presheath” solution V{sup ~}{sub qn}(r) by choosing the small potential and electricfield values corresponding to some large “matching radius” r{sub m}. Here, a straightforward but efficient numerical method is presented for systematically determining an optimal value of the matching radius at whichmore »

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