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Title: Screening and sheath formation in a nonequilibrium mixed Cairns-Tsallis electron distribution

Abstract

The effects of electron nonextensivity for a given nonthermality state, on Debye shielding and electrostatic sheath formation are examined. A physically meaningful Cairns-Tsallis distribution is outlined and a generalized expression for the Debye screening length λ{sub D}{sup q,α} is obtained. It is shown that an increase of the entropic index q causes λ{sub D}{sup q,α} to decrease whatever the amount of plasma nonthermality α. In addition, smaller pertinent values of q along with relatively higher values of α provide larger values of λ{sub D}{sup q,α}. The shielded electrostatic potential falls off as a function of distance more slowly as α increases, a result somewhat analogous to the dynamical shielding decrease (albeit in a different context) of a free charge as it begins to move. Moreover, smaller pertinent values of q along with relatively higher values of α are found to involve higher ion drift speed v{sub i0} for proper sheath formation. As α increases, the sheath electrostatic potential-gradient dΨ{sub s}/dξ becomes abruptly steep slowing down the energetic electrons leakage to the wall. Moreover, the sheath thickness broadens as the electron nonthermality strengthens.

Authors:
; ;  [1]
  1. Faculty of Physics, Theoretical Physics Laboratory (TPL), University of Bab-Ezzouar, USTHB, B.P. 32, El Alia, Algiers (Algeria)
Publication Date:
OSTI Identifier:
22410292
Resource Type:
Journal Article
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 22; Journal Issue: 5; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1070-664X
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; DEBYE LENGTH; DISTANCE; DISTRIBUTION; ELECTRIC POTENTIAL; FIRST WALL; ION DRIFT; LEAKS; PLASMA; PLASMA SHEATH; SHIELDING; SLOWING-DOWN; TAIL ELECTRONS; THICKNESS

Citation Formats

Bouzit, Omar, Gougam, Leila Ait, and Tribeche, Mouloud. Screening and sheath formation in a nonequilibrium mixed Cairns-Tsallis electron distribution. United States: N. p., 2015. Web. doi:10.1063/1.4919956.
Bouzit, Omar, Gougam, Leila Ait, & Tribeche, Mouloud. Screening and sheath formation in a nonequilibrium mixed Cairns-Tsallis electron distribution. United States. doi:10.1063/1.4919956.
Bouzit, Omar, Gougam, Leila Ait, and Tribeche, Mouloud. Fri . "Screening and sheath formation in a nonequilibrium mixed Cairns-Tsallis electron distribution". United States. doi:10.1063/1.4919956.
@article{osti_22410292,
title = {Screening and sheath formation in a nonequilibrium mixed Cairns-Tsallis electron distribution},
author = {Bouzit, Omar and Gougam, Leila Ait and Tribeche, Mouloud},
abstractNote = {The effects of electron nonextensivity for a given nonthermality state, on Debye shielding and electrostatic sheath formation are examined. A physically meaningful Cairns-Tsallis distribution is outlined and a generalized expression for the Debye screening length λ{sub D}{sup q,α} is obtained. It is shown that an increase of the entropic index q causes λ{sub D}{sup q,α} to decrease whatever the amount of plasma nonthermality α. In addition, smaller pertinent values of q along with relatively higher values of α provide larger values of λ{sub D}{sup q,α}. The shielded electrostatic potential falls off as a function of distance more slowly as α increases, a result somewhat analogous to the dynamical shielding decrease (albeit in a different context) of a free charge as it begins to move. Moreover, smaller pertinent values of q along with relatively higher values of α are found to involve higher ion drift speed v{sub i0} for proper sheath formation. As α increases, the sheath electrostatic potential-gradient dΨ{sub s}/dξ becomes abruptly steep slowing down the energetic electrons leakage to the wall. Moreover, the sheath thickness broadens as the electron nonthermality strengthens.},
doi = {10.1063/1.4919956},
journal = {Physics of Plasmas},
issn = {1070-664X},
number = 5,
volume = 22,
place = {United States},
year = {2015},
month = {5}
}