ABSTRACT
Investigating plasma plume interaction can give some insight into the physics of propagating streamers. How the energy is coupled to the fast propagating plasma plume is the key issue for nonequilibrium atmospheric pressure plasma jet (N-APPJ). One interesting phenomena of an APPJ is how its cross-section image indicates the donut shape of the plasma plume in a radial direction. The measurement and calculation of electron density can deduce the conductivity of the plasma channel. The theory attributed to plasma bullet propagation is G. A. Dawson’s photon-ionization theory. Dawson’s original work studied the generation of cathode-directed streamers in air and suggested that photoionization could facilitate streamer tip propagation at very high velocity. Photoionization is essential under conditions when the density of seed electrons is low, such as during the initial phase of the plasma jet, especially the very first plasma bullet.
