Investigation On Optical Characteristics Of Argon/Helium Plasma Jet At Atmospheric Pressure

In this paper,using argon or helium as the working gas,an atmospheric plasma jet generated by three kinds of electrode configurations is obtained,and the discharge characteristics of the plasma jet are investigated by electrical and optical methods.First,the discharge current and quantity of electric charge are measured by electrical method simultaneously.Meanwhile,we also investigated the discharge pulse and average discharge power.The plasma parameters of the plasma jet are studied by spatial resolved optical emission spectroscopy.In addition,excited electron temperature is estimated by spectral intensity of the corresponding spectral line.It is found that the discharge current pulses are asymmetric at different discharge phases.The number of discharge current pulses increases with the applied voltage.During the discharge process,we also measured the light pulse signal of the plasma jet at the quartz orifice.We found that the light pulse and the discharge current pulse showed a similar rule,they appeared almost simultaneously,but the light pulse duration was less than the discharge current pulse duration.With the increase of the applied voltage,the discharge powers of the three electrodes are increased.At the same applied voltage,the smaller the area of the electrode is,the longer the length of the plasma jet becomes.The length of plasma jet increases with the increase of applied voltage within a certain range,but it does not increase all the time.When the voltage increases to a certain critical value,the jet length curve shows a downward trend.Besides the above results,we also found that the excited electron temperature decreases with the increase of the gas flow rate,while the electron density of the plasma jet decreases with the gas flow rate.The experimental results show that the applied voltage has some influence on the discharge power and the length of jet is related to the electrode area.The gas flow rate plays an important role in the excited electron temperature and the spatial distribution of electron density.