Mode conversion in a randomly-stratified unmagnetized plasma

In real space plasmas, there exist random spatial variations of the plasma density as well as regular variations. The random density profile can affect the behaviors of resonance and wave propagation. In this paper, we investigate how the mode conversion from electromagnetic waves into electrostatic modes in a stratified unmagnetized plasma is affected by random density variations superimposed to the linear profile near the resonance. We obtain a surprising result that mode conversion is substantially enhanced in the presence of weak randomness. We interpret this result in terms of the enhancement of tunneling due to weak randomness.