A Multiple-Probe Microwave System for Plasma Studies

Abstract

This paper describes a fast-acting ~nicrowave diagnostic system which was developed for use with non-repetitive plas~nas, such as those in shocl; tubes and pulsed discharges, and which has proved i~seful in a wide variety of experimental configurations. The system may be used for either reflection or trans~nission measurements and gives a polar display of phase and amplitude in conjunction with timing marks. Sorile of the principal features are wide dynamic range, expansion of high attenuation regions of the display, and a presentation of data which is readily assessed visually. The system has been used a t microwave frequencies of 9.2 ki\/Ic, 9.7 bMc, 23.5 IcMc, and 34.5 kRiIc, with sa~npling periods from 0.1 msec to 0.1 psec a t 507, duty cycles.

Reflection of Circularly Polarized Electromagnetic Waves From an Anisotropic Plasma

“…The 8-in diameter, all-glass container for generating the plasma included a grid electrode structure (Bachynski and Gibbs, 1966) with a spacing of 2 in (1.56>..) and was positioned between the coils of an electromagnet in a Helmholtz configuration. The microwave signal, after being reflected from the plasma, passed back through the microwave lens into the aperture of the transmitting-receiving antenna, which fed the received signal into a multiple probe unit (Osborne, 1962) for recording. The necessary precautions (Bachynski and Cloutier, 1964) were taken to eliminate or minimize all undesirable interactions between the incident wave and the experimental system.…”