Numerical study of wave damping and amplification through ionization and recombination

Plasma wave energy in slowly ionizing or recombining plasma obeys general adiabatic invariants [1]. For a simple model of a homogeneous in space ionization we studied the behavior of a 1D Langmuir wave using our PIC code. However, discrepancies are found from the theory for linear waves [1] with unusual effects attributed possibly to ponderomotive focusing, namely, different damping rates for standing and moving waves.\\[4pt] [1] I.Y. Dodin and N.J. Fisch, Phys. Plasmas 17, 112113 (2010).