Amplification of Radio-Waves in Partially Ionized Gases

Abstract

The amplification of radio-frequency wave is observed in partially ionized gases, having large Ramsauer effect, in the absence of magnetic field. This paper gives results showing power gains of more than 4 db at 60 Mc/s and 3 db at 20 Mc/s in a xenon discharge plasma. By adjusting a dc grid current of a triode-type discharge tube, a strong attenuation or an amplification of an applied r f wave or an intense r f emission with no input signal is observed. This phenomenon occurs in pulses at some definite phase of a l f oscillation existing in the d c discharge when the detecting frequency is smaller than the critical one, which is somewhat smaller than the collision frequency of the plasma electrons. It is considered that experimental results are interpreted as a phenomenon of the negative absorption due to the stimulated brems-strahlung in partially ionized gases.