Modulation of the current in a nitrogen discharge by sound

Results are presentedfrom experimental studies of molecular nitrogen discharges in an acoustic wave field directed along the plasma column. It is found that creating an acoustic wave leads to a modulation of the discharge current at a frequency equal to that of the sound. It is shown experimentally that the depth of modulation increases with rising pressure and intensity of the sound and decreases with increasing discharge current (for a fixed pressure). A modulation of $\eta = 25\%$ in the discharge current is obtained at a nitrogen pressure of $50$ torr, a current of $40$ mA, and an acoustic intensity of $98$ dB. Adding argon or helium to the nitrogen discharge leads to a substantial reduction in the depth of modulation of the discharge current.