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Title: Large density variation predicted along the magnetic axis for cold electron plasmas in the Columbia Nonneutral Torus (CNT)

Abstract

Cold pure electron plasmas confined in Penning-Malmberg traps with mirror fields are known to exhibit density variations along field lines, such that the density is roughly proportional to the magnetic field strength, n{approx}B. The Columbia Nonneutral Torus (CNT) is the first stellarator designed to study pure electron plasmas, and exhibits substantial mirroring, with B{sub max}{approx_equal}1.8B{sub min}. However, results of a three-dimensional equilibrium solver, presented in this Letter, predict a factor of 5.3 increase in density from the minimum-field cross section to the maximum-field cross section along the magnetic axis, for a 1.5 cm Debye length plasma (a{approx_equal}15 cm for CNT). In this Letter, it is shown that the density variation of electron plasmas in mirror traps can be significantly enhanced in a device that has a cross section that varies from cylinder-like to slab-like, such as the CNT. A simple analytic expression is derived that describes the axial density variation in such a device, and it is found to agree well with the computational predictions for CNT.

Authors:
;  [1]
  1. Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027 (United States)
Publication Date:
OSTI Identifier:
20860416
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 13; Journal Issue: 12; Other Information: DOI: 10.1063/1.2405341; (c) 2006 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; DEBYE LENGTH; ELECTRONS; EQUILIBRIUM; MAGNETIC FIELDS; MAGNETIC MIRRORS; PLASMA; PLASMA CONFINEMENT; PLASMA DENSITY; RADIATION TRANSPORT; STELLARATORS; TRAPS; VARIATIONS

Citation Formats

Lefrancois, Remi G., and Pedersen, Thomas Sunn. Large density variation predicted along the magnetic axis for cold electron plasmas in the Columbia Nonneutral Torus (CNT). United States: N. p., 2006. Web. doi:10.1063/1.2405341.
Lefrancois, Remi G., & Pedersen, Thomas Sunn. Large density variation predicted along the magnetic axis for cold electron plasmas in the Columbia Nonneutral Torus (CNT). United States. doi:10.1063/1.2405341.
Lefrancois, Remi G., and Pedersen, Thomas Sunn. Fri . "Large density variation predicted along the magnetic axis for cold electron plasmas in the Columbia Nonneutral Torus (CNT)". United States. doi:10.1063/1.2405341.
@article{osti_20860416,
title = {Large density variation predicted along the magnetic axis for cold electron plasmas in the Columbia Nonneutral Torus (CNT)},
author = {Lefrancois, Remi G. and Pedersen, Thomas Sunn},
abstractNote = {Cold pure electron plasmas confined in Penning-Malmberg traps with mirror fields are known to exhibit density variations along field lines, such that the density is roughly proportional to the magnetic field strength, n{approx}B. The Columbia Nonneutral Torus (CNT) is the first stellarator designed to study pure electron plasmas, and exhibits substantial mirroring, with B{sub max}{approx_equal}1.8B{sub min}. However, results of a three-dimensional equilibrium solver, presented in this Letter, predict a factor of 5.3 increase in density from the minimum-field cross section to the maximum-field cross section along the magnetic axis, for a 1.5 cm Debye length plasma (a{approx_equal}15 cm for CNT). In this Letter, it is shown that the density variation of electron plasmas in mirror traps can be significantly enhanced in a device that has a cross section that varies from cylinder-like to slab-like, such as the CNT. A simple analytic expression is derived that describes the axial density variation in such a device, and it is found to agree well with the computational predictions for CNT.},
doi = {10.1063/1.2405341},
journal = {Physics of Plasmas},
number = 12,
volume = 13,
place = {United States},
year = {Fri Dec 15 00:00:00 EST 2006},
month = {Fri Dec 15 00:00:00 EST 2006}
}