Effect of microwave radiation on a shock-produced electron precursor

Results of experiments in which a small pressure driven shock tube was used to produce shocks in argon and air above Mach 10 are presented. This was strong enough to produce low level precursor ionization ahead of the shock. At the same time, the shock tube was used as a waveguide for pulsed X-band microwave radiation with a peak power of a few kilowatts. This further ionized the gas in the precursor region, resulting in an ionization wave which propagated very rapidly toward the microwave source. The velocity of this wave was measured as a function of the microwave power and an interpretation and comparison with other data is given.