Propagation of radiation pulses through gas-plasma mixtures
  We determine the linear optical susceptibility of a radiation pulse propagating through a mixture of a gas of atoms or molecules and a plasma. For a specific range of radiation and plasma frequencies, resonant generation of volume plasmons significantly amplifies the radiation intensity. The conditions for resonant amplification are derived from the dispersion relations in the mixture, and the amplification is demonstrated in a numerical simulation of pulse propagation. 
Karl-Peter Marzlin, Anuraj Panwar, M. Shajahan G. Razul and Barry C.   Sanders
physics.plasm-ph physics.optics