Asynchronous quenching and resonance excitation of ionization waves in positive columns

The non‐linear interactions between the self‐excited ionization wave and the forced oscillation are observed in the positive column of a glow discharge. The self‐excited wave is suppressed and quenched by applying the forced oscillation. The square of the amplitude of the self‐excited wave linearly decreases with the forced oscillation, and at the same time the frequency of the original wave somewhat shifts. Next, a resonance excitation of oscillation is observed, when a forced oscillation is applied after extinguishing the self‐excited wave by controlling the heater current of the tube. In order to explain these non‐linear phenomena the VAN DER POL equation is deduced from the basic equations for the ionization wave, extending the KEEN'S method for the ion‐acoustic wave. The approximate solution of the VAN DER POL equation by the asymptotic expansion can explain the experimental results with a quantitative agreement.