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Indexed by:期刊论文

Date of Publication:2016-04-27

Journal:JOURNAL OF PHYSICS D-APPLIED PHYSICS

Included Journals:SCIE、EI

Volume:49

Issue:16

ISSN No.:0022-3727

Key Words:ionization wave; plasma bullet; atmospheric pressure plasma; residual charge

Abstract:In this paper, by using a high precision synchronization system, the ignition time, velocity, and propagation properties of the ionization waves (IWs) have been investigated in detail from the 1st high voltage (HV) pulse to the sequential ones over a large range of the pulse-off time. In order to clarify the effects of previous ionization and excitation on the IW propagation, the density of the residual charges are controlled by varying the pulse-off time from 199 mu s to 15 mu s. The results show that the formation and propagation of IWs can be strongly affected by previous discharge. For a longer pulse-off time (100 mu s-190 mu s), the propagation velocity of plasma bullets are decreased from the 1st to the 10th HV pulse, then increased after the 10th pulse, and finally become stable after about 500 pulses. When the pulse-off time is reduced to 15 mu s, the propagation velocity of plasma bullets will rapidly increase and become stable after the 1st HV pulse. The ignition voltage is significantly reduced after the 1st HV pulse with the decrease in pulse-off time. Consequently, the generation and propagation of IWs in the tube are strongly affected by the accumulation of long-lived metastable helium (He) species and residual charges from previous discharges, which is important for understanding the plasma bullet behavior.