Continuity of steered vacuum arc with Al cathode and N2 flow under pressure of 0.1-5Pa is investigated. Two constant-current power supplies (60V open-circuit voltage/30V load voltage and 310V /240V) and a constant-voltage power supply with open-circuit voltage of 550V are used. Arc current is 30 A, N2 flow rate is 20ml/min, and transverse magnetic field density at the cathode edge is 1.2mT. The following results are obtained. (1) When the power supply with lower open-circuit and load voltages is used, decrease in pressure causes the arc to lose sustainability. (2) When the power supply with high open-circuit and load voltages is used, the arc can continue even at lower pressure. (3) When the power supply with higher load voltage is used, abnormal discharge behind the magnet field guide-disk may occur at lower pressure.
The above mentioned influence of power supply on arc continuity is interpreted in terms of column fall and generation of a new cathode spot.