Hysteresis and Transition to Chaos in a Thermionic Plasma Discharge

We report a period-doubling route to chaos in a modulated unmagnetized low pressure thermionic argon discharge. The bifurcation cascade has many similarities to a noisy logistic map. The non-modulated discharge shows strong hysteresis in the current voltage characteristic. Two distinct discharge states are identified by spatial plasma potential measurements and compared with the classification for higher pressures.