LANGMUIR TURBULENCE IN-SPACE PLASMAS

Recent developments in theoretical and numerical modeling of Langmuir turbulence in space and laboratory plasmas are addressed Kinetic effec ts, which have been missing from (fluid) traditional Zakharov equation models are explored using Vlasov code simulations. These studies are motivated by beam-driven Langmuir waves and particle distributions mea sured in Earth's foreshock region, and by beam-driven Langmuir waves a nd beams that underlie Type III solar radio emission in the solar wind . The nonlinear physical processes studied in these 1-D Vlasov simulat ions include bath wave-wave interactions and acceleration of particles by waves-leading to electron-beam flattening. We study bump-on-tail i nstabilities as boundary value problems, and determine the interplay i n space and time between beam plateau formation, stimulated wave-wave backscatter cascades, and strong turbulence wave-packet collapse.