LOW-FREQUENCY INSTABILITY IN WEAKLY IONIZED CURRENT-CARRYING MAGNETIZED PLASMAS .1. EXPERIMENTS ON INSTABILITY BEHAVIOR

Low-frequency drift wave-type instability of weakly ionized, weakly ma gnetized plasma in a dc discharge in argon is studied experimentally. The instability exists in the intermediate region OMEGA(ci) approximat ely nu(i), rho(i) approximately R between the conditions defining magn etization and unmagnetization of the ion plasma component (OMEGA(ci) a nd rho(i) are the ion gyrofrequency and gyroradius, nu(i) is the ion-n eutral collision frequency and R is the radius of the plasma column). The observations pertain to the appearance of the instability as a thr eshold effect and its dispersion properties. The behaviour of the inst ability is interpreted in relationship with the variation of the ambip olar field and its anomalously enhanced values. The effect of the long itudinal electric field sustaining the discharge is also discussed.