Undamping of acoustic plasmons in nonequilibrium plasmas

Abstract

Intraband pair excitation and plasmon spectra of nonequilibrium plasmas are analyzed using the dynamic dielectric function in the random-phase approximation. Nonequilibrium conditions are identified for which the Landau damping of acoustic plasmons vanishes. This acoustic-plasmon undamping is discussed for two-component plasmas and for one-component plasmas with a double-peaked distribution in momentum space.