Langmuir turbulence in space plasmas

Abstract

Recent developments in theoretical and numerical modeling of Langmuir turbulence in space plasmas are addressed. After reviewing the basic concepts of nonlinear wave‐wave and wave‐particle interactions, various kinetic effects, which have been missing from traditional Zakharov eqn. models, are explored using Vlasov code simulations. Two physical examples in weakly magnetized plasmas addressed in detail are: beam‐driven Langmuir waves and particle distributions in Earth’s foreshock region, and radiation‐driven Langmuir waves and accelerated particles in the ionosphere. The physical processes studied in the Vlasov simulations of these environments include electron‐beam flattening, acceleration of particles by waves, self‐consistent effects of accelerated particles on wave damping rates, and strong Landau damping of ion‐acoustic waves.