Temperature verification of the cold plasma jet generated by atmospheric dielectric barrier capillary discharge

Abstract

Summary form only given. A novel kind of millimeter cold plasma jet is achieved in atmospheric pressure of He, by capillary quartz dielectric barrier discharge (DBD) powered by a sinuous power source with frequency of 33 kHz. There are two different discharge regions in the generator: the filament discharge in the DBD gap and the plasma jet near the outlet of the capillary. The coexistence of the two discharge regions and the flow of the working gas are two basic requisites for generating the cold plasma jet. The temperature of the plasma jet is verified to be lower than any other continuous atmospheric discharges by two kinds of spectroscopic methods. The emission spectra from helium atoms is used to obtained the excitation temperature of the plasma jet by the Boltzmann plot scheme and the rotational spectral structure of the first negative band of nitrogen is used to simulate the plasma thermal-dynamic temperature. The tendencies of the two jet temperatures on the discharge power and the gas flow rate are investigated in detail. The results show that the plasma thermal-dynamic temperature lies in the range of 300-450 K while rising slightly with the discharge power and dropping with the gas flow rate. The excitation temperature of the jet rises with the discharge power but lies in range of 2000-3000 K, which is much lower than that of arc plasmas and plasma torches. The plasma power input is obtained from the discharge waveforms of voltage and current