ABSTRACT
The electron temperature is much higher than the temperature of the heavy particles in atmospheric pressure nonequilibrium plasmas. Due to the high collision frequency between electrons and heavy particles, the electrons lose their energy in a short period. If molecular gas is presented, the electrons quickly transfer their energy to molecular rotational and vibrational states because the energy levels of the latter can be much lower than that for electrons’ excitation and ionization [1-3]. This makes it difficult to obtain atmospheric pressure nonequilibrium plasmas with high electron energy. Thus the ionization efficiency in such case is low. Furthermore, when electronegative gases, such as O2 and SF6, are present, electrons could be absorbed by the gas in a timescale of tens of nanoseconds, or even shorter, which makes it even harder to obtain atmospheric pressure nonequilibrium plasma with electronegative gases [4].
