Temporal behavior of backscattering instabilities in a three-dimensional cylindrical hot spot: II. Modified decay regime and user guide

The space and time behavior of backscattering instabilities in a three-dime nsional cylindrical hot spot of finite lifetime is computed analytically in the modified decay regime. A uniform expression for the instantaneous back scattered power, valid for any time and any hot spot intensity in the modif ied decay regime, is proposed. It is shown that the finite transverse size of the hot spot leads to important diffraction effects that can significant ly reduce the hot spot backscattered energy. A "user guide" is provided for an easy use of this model whatever the instantaneous regime of the instabi lity: Standard decay, modified decay, and nonlinearly saturated (the hot sp ot depletion being taken into account heuristically). All the parameters ne eded in this model are given in physical units for both stimulated Brilloui n scattering and stimulated Raman scattering. (C) 1999 American Institute o f Physics. [S1070-664X(99)02809-8].