Low-frequency instability in weakly ionized current-carrying magnetized plasmas: Pt. 1

Low-frequency drift wave-type instability of weakly ionized, weakly magnetized plasma in a dc discharge in argon is studied experimentally. The instability exists in the intermediate region between the conditions defining magnetization and unmagnetization of the ion plasma component. The observations pertain to the appearance of the instability as a threshold effect and its dispersion properties. The behaviour of the instability is interpreted in relationship with the variation of the ambipolar field and its anomalously enhanced values. The effect of the longitudinal electric field sustaining the discharge is also discussed. (author)