Accession Number : AD0712190

Title :   RADIO-FREQUENCY FLOATING DOUBLE PROBE AS A PLASMA DIAGNOSTIC,

Corporate Author : VICTORIA UNIV (BRITISH COLUMBIA) DEPT OF PHYSICS

Personal Author(s) : Oliver,B. M. ; Clements,R. M. ; Smy,P. R.

Report Date : 17 NOV 1969

Pagination or Media Count : 6

Abstract : A floating double probe operating at radio frequencies in the MHz range has been developed to the point where measurements of sheath capacitance and resistance yield values for plasma ionization density and electron temperature with an accuracy of approximately 8% and approximately 16%, respectively. The experimental technique used supersedes previous methods in that it enables sheath capacities as low as .01 pF to be measured. The analysis of the results has been extended to cover the important nonplanar (cylindrical) sheath case. As a result of these two developments, the technique is now applicable to small diameter probes which are essential for measurements in most gas discharge plasmas. The performance of the probes has been checked over a range of plasma densities and working frequencies and has been found to give results which are in good agreement with microwave cavity and dc probe measurements. This type of measurement has various advantages over the usual dc probe methods in terms of complete isolation, but it is expected that its main application will be in situations where the use of the dc probe is suspect due to probe surface contamination effects. (Author)

Descriptors :   (*LANGMUIR PROBES, RADIOFREQUENCY), (*PLASMA MEDIUM, MEASUREMENT), ELECTRON DENSITY, ELECTRICAL RESISTANCE, TEMPERATURE, RADIATION MEASURING INSTRUMENTS, CAPACITANCE, ELECTRICAL IMPEDANCE, CANADA

Subject Categories : Test Facilities, Equipment and Methods
      Plasma Physics and Magnetohydrodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE