Strongly coupled large-angle stimulated Raman scattering of short laser pulse in plasma-filled capillary

Strongly coupled large-angle stimulated Raman scattering (LA SRS) of a short intense laser pulse develops in a plane plasma-filled capillary differently than in a plasma with open boundaries. Coupling the laser pulse to a capillary seeds the LA SRS in the forward direction (scattering angle smaller than $π∕2$⁠) and can thus produce a high instability level in the vicinity of the entrance plane. In addition, oblique mirror reflections off capillary walls partly suppress the lateral convection of scattered radiation and increase the growth rate of the SRS under arbitrary (not too small) angle. Hence, the saturated convective gain falls with an angle much slower than in an unbounded plasma and even for the near-forward SRS can be close to that of the direct backscatter. At a large distance, the LA SRS evolution in the interior of the capillary is dominated by quasi-one-dimensional leaky modes whose damping is related to the leakage of scattered radiation through the walls.