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

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_gdk with the group velocity u_g~c_s²/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.