Laser emission filamentation - Transient linear regime, effect of induced spatial noncoherence, and supersonic collapse

The filamentation instability of laser emission is investigated analytically in the case of a coherent laser beam and in the case of emission consisting of a large number of beams with a wide frequency spectrum. It is shown that induced spatial noncoherence cannot stabilize long-wave thermal instabilities. It is also found that, in the linear regime, consideration of ion energy leads to the possibility of a supersonic filamentation collapse.