Experimental Study of Microwave Transmission through a Decaying Plasma

摘要

The physics of pulsed microwave, or radio frequency (rf), transmission through a decaying plasma column, is studied experimentally. A plasma column is formed in Argon or Nitrogen gases, to represent the neutral gas breakdown due to an rf pulse. Initially the electron frequency is greater than the microwave frequency. An rf pulse capable of plasma reionization is applied across the plasma column at varying times in the plasma's decay phase (the plasma afterglow). We have studied the variation of the transmitted rf pulse characteristics, pulse width and amplitude, as a function of the time into the afterglow. The ionization frequency of argon by a microwave pulse is found experimentally to be within 20% of the theoretical value. The comparison of ionization frequency is useful in establishing the applicability of earlier cavity measurements to present day open geometry systems used in transmission/propagation experiments. (rh)