skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Equilibrium and magnetic properties of a rotating plasma annulus

Abstract

Local linear analysis shows that magneto-rotational instability can be excited in laboratory rotating plasmas with a density of 10{sup 19} m{sup -3}, a temperature on the order of 10 eV, and a magnetic field on the order of 100 G. A laboratory plasma annulus experiment with a dimension of {approx}1 m, and rotation at {approx}0.5 sound speed is described. Correspondingly, magnetic Reynolds number of these plasmas is {approx}1000, and magnetic Prandtl number ranges from about one to a few hundred. A radial equilibrium, {rho}U{sub {theta}}{sup 2}/r=d(p+B{sub z}{sup 2}/2{mu}{sub 0})/dr=K{sub 0}, with K{sub 0} being a nonzero constant, is proposed for the experimental data. Plasma rotation is observed to drive a quasisteady diamagnetic electrical current (rotational current drive) in a high-{beta} plasma annulus. The rotational energy depends on the direction and the magnitude of the externally applied magnetic field. Radial current (J{sub r}) is produced through biasing the center rod at a negative electric potential relative to the outer wall. J{sub r}xB{sub z} torque generates and sustains the plasma rotation. Rotational current drive can reverse the direction of vacuum magnetic field, satisfying a necessary condition for self-generated closed magnetic flux surfaces inside plasmas. The Hall term is found to be substantialmore » and therefore needs to be included in the Ohm's law for the plasmas. Azimuthal magnetic field (B{sub {theta}}) is found to be comparable with the externally applied vacuum magnetic field B{sub z}, and mainly caused by the electric current flowing in the center cylinder; thus, B{sub {theta}}{proportional_to}r{sup -1}. Magnetic fluctuations are anisotropic, radial-dependent, and contain many Fourier modes below the ion cyclotron frequency. Further theoretical analysis reflecting these observations is needed to interpret the magnetic fluctuations.« less

Authors:
; ; ;  [1]
  1. Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
Publication Date:
OSTI Identifier:
21254521
Resource Type:
Journal Article
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 15; Journal Issue: 10; Other Information: DOI: 10.1063/1.3002395; (c) 2008 American Institute of Physics; 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; EQUILIBRIUM; FLUCTUATIONS; MAGNETIC FIELDS; MAGNETOHYDRODYNAMICS; PLASMA DENSITY; PLASMA DIAMAGNETISM; PLASMA INSTABILITY; ROTATING PLASMA

Citation Formats

Zhehui, Wang, Jiahe, Si, Wei, Liu, and Hui, Li. Equilibrium and magnetic properties of a rotating plasma annulus. United States: N. p., 2008. Web. doi:10.1063/1.3002395.
Zhehui, Wang, Jiahe, Si, Wei, Liu, & Hui, Li. Equilibrium and magnetic properties of a rotating plasma annulus. United States. https://doi.org/10.1063/1.3002395
Zhehui, Wang, Jiahe, Si, Wei, Liu, and Hui, Li. 2008. "Equilibrium and magnetic properties of a rotating plasma annulus". United States. https://doi.org/10.1063/1.3002395.
@article{osti_21254521,
title = {Equilibrium and magnetic properties of a rotating plasma annulus},
author = {Zhehui, Wang and Jiahe, Si and Wei, Liu and Hui, Li},
abstractNote = {Local linear analysis shows that magneto-rotational instability can be excited in laboratory rotating plasmas with a density of 10{sup 19} m{sup -3}, a temperature on the order of 10 eV, and a magnetic field on the order of 100 G. A laboratory plasma annulus experiment with a dimension of {approx}1 m, and rotation at {approx}0.5 sound speed is described. Correspondingly, magnetic Reynolds number of these plasmas is {approx}1000, and magnetic Prandtl number ranges from about one to a few hundred. A radial equilibrium, {rho}U{sub {theta}}{sup 2}/r=d(p+B{sub z}{sup 2}/2{mu}{sub 0})/dr=K{sub 0}, with K{sub 0} being a nonzero constant, is proposed for the experimental data. Plasma rotation is observed to drive a quasisteady diamagnetic electrical current (rotational current drive) in a high-{beta} plasma annulus. The rotational energy depends on the direction and the magnitude of the externally applied magnetic field. Radial current (J{sub r}) is produced through biasing the center rod at a negative electric potential relative to the outer wall. J{sub r}xB{sub z} torque generates and sustains the plasma rotation. Rotational current drive can reverse the direction of vacuum magnetic field, satisfying a necessary condition for self-generated closed magnetic flux surfaces inside plasmas. The Hall term is found to be substantial and therefore needs to be included in the Ohm's law for the plasmas. Azimuthal magnetic field (B{sub {theta}}) is found to be comparable with the externally applied vacuum magnetic field B{sub z}, and mainly caused by the electric current flowing in the center cylinder; thus, B{sub {theta}}{proportional_to}r{sup -1}. Magnetic fluctuations are anisotropic, radial-dependent, and contain many Fourier modes below the ion cyclotron frequency. Further theoretical analysis reflecting these observations is needed to interpret the magnetic fluctuations.},
doi = {10.1063/1.3002395},
url = {https://www.osti.gov/biblio/21254521}, journal = {Physics of Plasmas},
issn = {1070-664X},
number = 10,
volume = 15,
place = {United States},
year = {Wed Oct 15 00:00:00 EDT 2008},
month = {Wed Oct 15 00:00:00 EDT 2008}
}