It was found that low frequency discharge current oscillation of two inductors with the same nominal value is extremely different. To decide the general characteristic of thruster inductors, relationship between the frequency characteristic of inductors and low frequency oscillation is studied in experiments at the same operation conditions. Experimental results indicate that the differences of low frequency discharge current oscillation were caused by the different frequency characteristic of inductor. As the corner frequency of inductors increases, the discharge current low frequency oscillation declines at first and then slightly turns up after a certain frequency. Through analysis from the perspective of control system, advantageous frequency characteristics of thruster inductors in filter are suggested. (C) 2010 American Vacuum Society. [DOI: 10.1116/1.3457152]