Comparison of Microwave and Langmuir Probe Measurements on a Gaseous Plasma†

Abstract

Microwave and Langmuir probe measurements were carried out simultaneously on the plasma of a low-pressure mercury-vapour are. The values of the average electron density, obtained by the two types of measurements, are in reasonable agreement. The effect of the well-known Lorentz term in the evaluation of the electron density in low-density plasmas is discussed in the context of microwave measurements. The method of Hoyaux for obtaining the space potential from the voltage-current characteristic for the Langmuir probe is confirmed.