In order to improve the stability of corona discharge

the Trichel pulse in oxygen at low pressure was investigated by using a needle-plane electrode.Moreover

the evolution of U-I curve and the images of discharge at different discharge currents were measured. Results show that the discharge is divided into Townsend mode

Trichel pulse mode

and abnormal glow mode when the discharge current increases. Both of discharge pulsing current and pulsing voltage can be obtained at 532 Pa. A complete pulse consists of a quick rising time

a long destroying time

and a much long duration time

which are much longer than those of the pulses obtained at high pressure. The critical electric field controls the rising and destroying time of the pulses. The current peak appears earlier than the minimum of voltage. At the same time

the results show that the oxygen favors the formation of Trichle pulse. With the increasing of oxygen content

the waiting time increases

the width of pulses is constant

and the frequency of pulses decreases. The frequency of pulses increases linearly with the increase of averaged discharge current

and decreases with the increase of parallel capacitance.