Microwave diagnostics of a strong arc discharge plasma in SF6

The paper deals with the microwave free-space diagnostics of high collision arc discharge plasmas. It is found that information about the electron density N and the collision frequency ν in such a plasma can be obtained from the energy transmitted through the plasma by an electromagnetic wave. The phase of the electromagnetic wave cannot be used since it is almost the same as that of a wave passing through vacuum. These basic concepts are verified experimentally at a frequency of 37.5 GHz. It is shown how the time dependence of the electron density in a plasma with constant and with time variable collision frequency may be evaluated. (orig.)