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Title: Electron reflection effects on particle and heat fluxes to positively charged dust subject to strong electron emission

A new model describing dust charging and heating in unmagnetized plasmas in the presence of large electron emission currents is presented. By accounting for the formation of a potential well due to trapped emitted electrons when the dust is positively charged, this model extends the so-called OML + approach, thus far limited to thermionic emission, by including electron-induced emission processes, and in particular low-energy quasi-elastic electron reflection. Revised semi-analytical formulas for the current and heat fluxes associated with emitted electrons are successfully validated against particle-in-cell simulations and predict an overall reduction of dust heating by up to a factor of 2. Finally, when applied to tungsten dust heating in divertor-like plasmas, the new model predicts that the dust lifetime increases by up to 80%, as compared with standard orbital-motion-limited estimates.
Authors:
 [1] ;  [2] ; ORCiD logo [1] ;  [1]
  1. KTH Royal Inst. of Technology, Stockholm (Sweden). Space and Plasma Physics
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Report Number(s):
LA-UR-18-21064
Journal ID: ISSN 1070-664X
Grant/Contract Number:
AC52-06NA25396
Type:
Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 25; Journal Issue: 6; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE Office of Science (SC). Fusion Energy Sciences (FES) (SC-24); USDOE
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Magnetic Fusion Energy
OSTI Identifier:
1481988
Alternate Identifier(s):
OSTI ID: 1454349

Vignitchouk, L., Delzanno, G. L., Tolias, P., and Ratynskaia, S.. Electron reflection effects on particle and heat fluxes to positively charged dust subject to strong electron emission. United States: N. p., Web. doi:10.1063/1.5026384.
Vignitchouk, L., Delzanno, G. L., Tolias, P., & Ratynskaia, S.. Electron reflection effects on particle and heat fluxes to positively charged dust subject to strong electron emission. United States. doi:10.1063/1.5026384.
Vignitchouk, L., Delzanno, G. L., Tolias, P., and Ratynskaia, S.. 2018. "Electron reflection effects on particle and heat fluxes to positively charged dust subject to strong electron emission". United States. doi:10.1063/1.5026384.
@article{osti_1481988,
title = {Electron reflection effects on particle and heat fluxes to positively charged dust subject to strong electron emission},
author = {Vignitchouk, L. and Delzanno, G. L. and Tolias, P. and Ratynskaia, S.},
abstractNote = {A new model describing dust charging and heating in unmagnetized plasmas in the presence of large electron emission currents is presented. By accounting for the formation of a potential well due to trapped emitted electrons when the dust is positively charged, this model extends the so-called OML+ approach, thus far limited to thermionic emission, by including electron-induced emission processes, and in particular low-energy quasi-elastic electron reflection. Revised semi-analytical formulas for the current and heat fluxes associated with emitted electrons are successfully validated against particle-in-cell simulations and predict an overall reduction of dust heating by up to a factor of 2. Finally, when applied to tungsten dust heating in divertor-like plasmas, the new model predicts that the dust lifetime increases by up to 80%, as compared with standard orbital-motion-limited estimates.},
doi = {10.1063/1.5026384},
journal = {Physics of Plasmas},
number = 6,
volume = 25,
place = {United States},
year = {2018},
month = {6}
}