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Title: Direct Vlasov simulations of electron-attracting cylindrical Langmuir probes in flowing plasmas

Abstract

Current collection by positively polarized cylindrical Langmuir probes immersed in flowing plasmas is analyzed using a non-stationary direct Vlasov-Poisson code. A detailed description of plasma density spatial structure as a function of the probe-to-plasma relative velocity U is presented. Within the considered parametric domain, the well-known electron density maximum close to the probe is weakly affected by U. However, in the probe wake side, the electron density minimum becomes deeper as U increases and a rarified plasma region appears. Sheath radius is larger at the wake than at the front side. Electron and ion distribution functions show specific features that are the signature of probe motion. In particular, the ion distribution function at the probe front side exhibits a filament with positive radial velocity. It corresponds to a population of rammed ions that were reflected by the electric field close to the positively biased probe. Numerical simulations reveal that two populations of trapped electrons exist: one orbiting around the probe and the other with trajectories confined at the probe front side. The latter helps to neutralize the reflected ions, thus explaining a paradox in past probe theory.

Authors:
;  [1]
  1. Departamento de Física Aplicada, Escuela Técnica Superior de Ingenieros Aeronáuticos, Universidad Politécnica de Madrid, Plaza de Cardenal Cisneros 3, 28040 Madrid (Spain)
Publication Date:
OSTI Identifier:
22304104
Resource Type:
Journal Article
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 21; Journal Issue: 7; Other Information: (c) 2014 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; COMPUTERIZED SIMULATION; CYLINDRICAL CONFIGURATION; DISTRIBUTION FUNCTIONS; ELECTRIC FIELDS; ELECTRON DENSITY; IONS; LANGMUIR PROBE; PLASMA DENSITY; RADIAL VELOCITY; TRAPPED ELECTRONS

Citation Formats

Sánchez-Arriaga, G., and Pastor-Moreno, D. Direct Vlasov simulations of electron-attracting cylindrical Langmuir probes in flowing plasmas. United States: N. p., 2014. Web. doi:10.1063/1.4889732.
Sánchez-Arriaga, G., & Pastor-Moreno, D. Direct Vlasov simulations of electron-attracting cylindrical Langmuir probes in flowing plasmas. United States. https://doi.org/10.1063/1.4889732
Sánchez-Arriaga, G., and Pastor-Moreno, D. 2014. "Direct Vlasov simulations of electron-attracting cylindrical Langmuir probes in flowing plasmas". United States. https://doi.org/10.1063/1.4889732.
@article{osti_22304104,
title = {Direct Vlasov simulations of electron-attracting cylindrical Langmuir probes in flowing plasmas},
author = {Sánchez-Arriaga, G. and Pastor-Moreno, D.},
abstractNote = {Current collection by positively polarized cylindrical Langmuir probes immersed in flowing plasmas is analyzed using a non-stationary direct Vlasov-Poisson code. A detailed description of plasma density spatial structure as a function of the probe-to-plasma relative velocity U is presented. Within the considered parametric domain, the well-known electron density maximum close to the probe is weakly affected by U. However, in the probe wake side, the electron density minimum becomes deeper as U increases and a rarified plasma region appears. Sheath radius is larger at the wake than at the front side. Electron and ion distribution functions show specific features that are the signature of probe motion. In particular, the ion distribution function at the probe front side exhibits a filament with positive radial velocity. It corresponds to a population of rammed ions that were reflected by the electric field close to the positively biased probe. Numerical simulations reveal that two populations of trapped electrons exist: one orbiting around the probe and the other with trajectories confined at the probe front side. The latter helps to neutralize the reflected ions, thus explaining a paradox in past probe theory.},
doi = {10.1063/1.4889732},
url = {https://www.osti.gov/biblio/22304104}, journal = {Physics of Plasmas},
issn = {1070-664X},
number = 7,
volume = 21,
place = {United States},
year = {Tue Jul 15 00:00:00 EDT 2014},
month = {Tue Jul 15 00:00:00 EDT 2014}
}