Langmuir wave filamentation instability

A Langmuir wave (LW) model is constructed whose equilibria are consistent with stimulated Raman scatter optimization, with Hamiltonian dynamics, and with rotational invariance. Linear instability analysis includes terms to all orders in wave amplitude and fluctuation wavenumber expansions, delta k. Resultant LW modulational instability is nonstandard: As the LW amplitude increases, the unstable delta k range first expands and then shrinks to zero. Large amplitude wave model dynamics requires hyperdiffraction terms if k lambda(D)<0.45, lest artificially small length scales become unstable. (C) 2008 American Institute of Physics.