Studies of Antenna Breakdown in the Presence of a Plasma Sheath Including Effects of Forced Convection

摘要

Interest in the reentry communications problem has motivated an effort to generate a plasma layer on a model in a supersonic wind tunnel using a nitrogen dc plasma jet mounted in the blunt nose of the model. Langmuir probe data indicate non-uniform charged particle distribution with a peak about 0.25 to 0.4 inches from the model surface. Results of high power X-band antenna measurements, both visually and with VSWR and received power instrumentation, show a distinct indication of antenna breakdown persisting with the plasma layer present. However, changes in VSWR and received power after breakdown are more gradual. It is suggested that changes in slope of a received power curve as a function of applied power be used as an indication of breakdown in the presence of a plasma layer. (Author)