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Using Planar Probes to Estimate the Hall Electron Drift Speed in Magnetized Plasma
Author(s) -
Vetushka A.,
Karkari S. K.,
ArandaGonzalvo Y.,
Bradley J. W.
Publication year - 2004
Publication title -
contributions to plasma physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.531
H-Index - 47
eISSN - 1521-3986
pISSN - 0863-1042
DOI - 10.1002/ctpp.200410095
Subject(s) - saturation current , plasma , electron , planar , physics , anisotropy , electron temperature , saturation (graph theory) , atomic physics , magnetic field , ion , optics , voltage , nuclear physics , computer graphics (images) , mathematics , quantum mechanics , combinatorics , computer science
A circular planar probe of diameter 4 mm has been used to determine the ratio of the electron E × B drift speed V d to the thermal speed V th in the bulk plasma of a magnetron discharge. It is found that when the probe is orientated into the E × B drift, with its surface parallel to the local B‐field, significantly higher electron saturation currents are detected than when the probe is orientated away from the drift (i.e. 180 degrees from this orientation). Using the electron and ion saturation current measurements and a simple model of the anisotropic plasma‐probe system, which assumes both Hall and collisional cross‐field transport, V d /V th has been determined at different positions in the bulk plasma. The maximum in V d /V th is found to be about 0.14 (corresponding to V d = 1 · 10 5 ms –1 ) and the measured distribution of drift current agrees well with data that was found in a previous study, in which V d was determined from the knowledge of E and B, namely V d = E × B/B 2 , and with V th determined from electron temperature measurements, i.e. V th = (2kT e /m e ) 1/2 . (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)