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Title: On the interpretation of diamagnetic loop measurements for a current-carrying plasma column in a conducting chamber

Abstract

A general expression is derived for the signal of a magnetic loop encircling a plasma column inside a conducting chamber with nonuniform current distribution over the plasma cross-section. The ratio of the paramagnetic component to the diamagnetic component of the signal is shown to be independent of the loop radius. Both components increases the loop radius decreases from the chamber radius to the plasma radius. From the derived expressions, the paramagnetic component of the signal is calculated numerically for several current distributions including those of interest for the experiments. At a given total current, the paramagnetic component of the signal may vary considerably, which generally has to be taken into account in interpreting experimental data. The results of the calculations are used to process the data obtained in the experiments on the SPIN plasma device.

Authors:
; ;  [1];  [2]
+ Show Author Affiliations
  1. AN SSSR, Novosibirsk (Russian Federation). Inst. Yadernoj Fiziki
  2. Texas Univ., Austin, TX (United States). Inst. for Fusion Studies
Publication Date:
Research Org.:
Texas Univ., Austin, TX (United States). Inst. for Fusion Studies
Sponsoring Org.:
USDOE, Washington, DC (United States)
OSTI Identifier:
10125472
Report Number(s):
DOE/ET/53088-628; IFSR-628
ON: DE94007107; BR: 39KG01000/AT0520240
DOE Contract Number:
FG05-80ET53088
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: Oct 1993
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; PLASMA; MAGNETIC FIELDS; ELECTRIC CURRENTS; 700430; MAGNET COILS AND FIELDS

Citation Formats

Aleynikov, A.N., Cherkassky, V.S., Knyazev, B.A., and Breizman, B.N. On the interpretation of diamagnetic loop measurements for a current-carrying plasma column in a conducting chamber. United States: N. p., 1993. Web. doi:10.2172/10125472.
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Aleynikov, A.N., Cherkassky, V.S., Knyazev, B.A., & Breizman, B.N. On the interpretation of diamagnetic loop measurements for a current-carrying plasma column in a conducting chamber. United States. doi:10.2172/10125472.
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Aleynikov, A.N., Cherkassky, V.S., Knyazev, B.A., and Breizman, B.N. Fri . "On the interpretation of diamagnetic loop measurements for a current-carrying plasma column in a conducting chamber". United States. doi:10.2172/10125472. https://www.osti.gov/servlets/purl/10125472.
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@article{osti_10125472,
title = {On the interpretation of diamagnetic loop measurements for a current-carrying plasma column in a conducting chamber},
author = {Aleynikov, A.N. and Cherkassky, V.S. and Knyazev, B.A. and Breizman, B.N.},
abstractNote = {A general expression is derived for the signal of a magnetic loop encircling a plasma column inside a conducting chamber with nonuniform current distribution over the plasma cross-section. The ratio of the paramagnetic component to the diamagnetic component of the signal is shown to be independent of the loop radius. Both components increases the loop radius decreases from the chamber radius to the plasma radius. From the derived expressions, the paramagnetic component of the signal is calculated numerically for several current distributions including those of interest for the experiments. At a given total current, the paramagnetic component of the signal may vary considerably, which generally has to be taken into account in interpreting experimental data. The results of the calculations are used to process the data obtained in the experiments on the SPIN plasma device.},
doi = {10.2172/10125472},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Fri Oct 01 00:00:00 EDT 1993},
month = {Fri Oct 01 00:00:00 EDT 1993}
}
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Technical Report:
View Technical Report (0.81 MB)
DOI:  10.2172/10125472
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  • ; ; ; ... - Physics of Plasmas; (United States)
    An expression is derived for the signal of a magnetic loop encircling a plasma column inside a conducting chamber with nonuniform current distribution over the plasma cross section. The plasma with radius much smaller than the length of the column is assumed to be in a quasistationary force-balanced state. The ratio of the paramagnetic component to the diamagnetic component of the signal is shown to be independent of the loop radius. Both components increase as the loop radius decreases from the chamber radius to the plasma radius. From the derived expressions, the paramagnetic component of the signal is calculated numericallymore » for several current distributions including those of interest for the experiments. At a given total current, the paramagnetic component of the signal may vary considerably, which generally has to be taken into account in interpreting experimental data. The results of the calculations are used to process the data obtained in the experiments on the SPIN plasma device [Knyazev [ital et] [ital al]., Characteristics of plasma produced by a linear discharge in the metal chamber of the SPIN device,'' J. Tech. Phys. [bold 63], 49 (1993) (in Russian)].« less

  • ; ;
    By means of the neighbouring equilibrium method the saturation level of the kink instability of a current carrying plasma column is investigated. We obtain the helical equilibrium which is the stationary saturated stage of kink instability. The analysis is performed for the rounded current profile case and shows that the shell has very strong suppression effect on the saturation level.

  • The axially symmetric modes of propagation of hydromagnetic disturbances in a current carrying plasma column with a nonuniform mass density distribution are investigated. The current density is assumed to be uniform and the column is surrounded by a vacuum. In the limit of small discharge current, two uncoupled modes of oscillation can take place. One involves a radial pulsation against the externally imposed axial magnetic field with associated pressure, density, and temperature fluctuations, while the other is a torsional motion. The torsional mode is not accompanied by flucthations in the thermodynamic properties. The properties of the radial waves in amore » nonuniform column are investigated and found not to be markedly different than those for a column of uniform density with the exception that the phase velocity and cutoff frequency are considerably higher. Due to the density gradient in the column, the radial wave is confined largely near the column axis, especially at high frequencies. This is due to refraction produced by variation in the Aifven speed across the column. As opposed to the radial waves, the torsional wave is radically altered by the presence of a density gradient. The pbase velocity is exactly the Aifven speed based upon the local density and, therefore, a function of the radial distance from the center of the column. For a given frequency, the wave length is also variable changing from a minimum value at the center to infinity at the plasma-vacuum interface. Thus, an original plane disturbance will become distorted as it moves down the column. Due to the difference in phase, the axial current density and space charge density, which are functions of the gradients of the field quantities, increase with distance from the source. The total currert, however, is always zero and the total charge per unit length does not grow but fluctuates in time balanced by an equal and opposite fluctuation at the surface. The attenuation of both the radial and torsional modes due to resistivity and viscosity is calculated using an energy principle. It is found that the attenuation of the torsional mode is greatly increased due to the increase in axial current density and radial velocity gradient as the wave progresses. (auth)« less

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