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Ion density and current distributions in a propagating current sheet, determined by microwave reflection technique

Published online by Cambridge University Press:  13 March 2009

W. R. Ellis
Affiliation:
Department of the Aerospace and Mechanical Sciences, Princeton University, Princeton, N.J..
R. G. Jahn
Affiliation:
Department of the Aerospace and Mechanical Sciences, Princeton University, Princeton, N.J..

Abstract

Electron and ion density distributions and the problem of electron/ion current partitioning are studied in a large radius Z-pinch in argon. Radial scans of the electron density and temperature proffles in the propagating sheet are obtained with a multi-purpose microwave interferometer which measures the complex refiexion coefficient from the plasma. At 70 GHz the probe resolves densities up to 1017 cm−3 over dimensions of ˜ 4 mm. Proffles of the electric and magnetic field components are obtained using standard probe techniques, and these data are used to calculate ion and electron current components in the sheet.

Within the approximations of MHD theory, calculations show that the overall axial current pattern is built up of four interior zones alternately dominated by electron or ion current. This structure is observed to be closely correlated with variations of the Hall parameter, Wb/vc, about the value of unity through the sheet, which suggests that this parameter might be used as a guide to the relative importance of ion conduction in pinch discharge current sheets.

Type
Research Article
Copyright
Copyright © Cambridge University Press 1969

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