Self-alignment of ions drifting in plasma

The hypothesis that drift of ions in a plasma causes their spontaneous alignment with a quadrupole orientation of their angular momentum was confirmed in an experiment with ionization of argon in a 100 to 400 V hollow-cathode discharge tube 5 cm long and 3 cm in diameter. Distinct difference signals corresponding to the fine structure were recorded within the narrow low-pressure range of 0.1 to 0.5 torr at discharge currents of 10 to 60 mA. A comparison of difference signals from atomic argon and from weakly ionized argon proves the drift hypothesis of self-alignment most directly. The experimental data confirm also other predictions, namely that self-alignment of ions is closely associated with collisional mixing of half-levels in the fine structure of ions and that the self-alignment signal originates from a deviation of the ratio (N sub 1)/(N sub 2) of respective half-level populations from the ratio (g sub 1)/(g sub 2) of their statistical weights.