Description of plasma bullet in plasma jet in terms of wave-packet of plasma diffusion

Abstract

Summary form only given. The propagation of plasma bullet in a plasma jet is described under the base of fluid theory of plasma diffusion and plasma drift as well as the gas flow. The origin of plasma bullet is analyzed to be the electrostatic plasma diffusion wave propagating in the plasma column of plasma jets. The plasma diffusion waves, electron wave as well as ion wave, propagate as the form of wave-packet modulated to the operation frequency of voltage pulse. The waves have the dispersion relation of ω∼(u d +u b +u n )k where the phase velocity is the addition of fluid such as drift velocity u d , gas blowing velocity u b , and plasma diffusion velocity u n . The waves are modulated to be the wave-packet of dω∼u g dk with the group velocity u g ∼c s 2/u n ∼(104–105) m/s where the acoustic velocity is c s ∼103 m/s and the diffusion velocity is u n ∼(10–102) m/s estimated in a plasma jet device. The plasma diffusion wave propagates resistively against the slope of plasma density gradient1.