The Study Of Pulse-modulated Radio-frequency Atmospheric Pressure Dielectric Barrier Glow Discharge

Recently, atmospheric pressure glow discharges (APGDs) have attracted much attention for their feasibility and convenience in a wide scope of potential applications, including surface modifications, material synthesis, and biological sterilization. They can be obtained at atmospheric pressure without need of vacuum system. By applying pulse modulation on radio frequency, excitation power, the ignition and duration of discharge burst can be manipulated in atmospheric pressure glow discharge, in which, heat accumulation effect and plasma temperature can be reduced. It proposed a way to improve discharge stability.. In this paper, we study the characteristics of pulse-modulated radio frequency atmospheric pressure glow discharge. The obtained results are introduced as following:1. An experimental study of 13.56 MHz radio-frequency glow discharges in atmospheric helium modulated by pulses with repetition frequency of 100 kHz was carried out. It is shown that the discharge during power on has similar characteristics with that of discharge without pulsing, except during the discharge ignition and extinguishment phase. The electrical and optical characteristics of discharge in phases of ignition and extinguishment were studied by time-resolved imaging and optical emission spectrograph. The temporal evolution of discharge ignition and extinguishment phases were investigated by plasma image intensity, discharge spatial profile and optical emission line intensity.2. An experimental study of 15 MHz glow discharges in atmospheric helium modulated by pulses with repetition frequency of 500 kHz and duty cycle of 6% and 8% was studied. In each discharge burst, the discharge is restricted to operate in ignition phase with duration of one or two radio-frequency cycles. The number of rf cycle in each discharge burst is demonstrated by means of discharge current, image intensity, and optical emission intensity at line of 706 nm. The ignition characteristics in terms of spatial-temporal evolution of discharge interelectrode structure and optical emission intensity are investigated by time resolved imaging. It proposes a way to obtain atmospheric radio frequency glow discharge with high stability and reduced power consumption by operating discharge in ignition phase.