  In a laser-irradiated plasma, the Langdon effect can result in a
super-Gaussian electron energy distribution function (EEDF), imposing
significant influences on the stimulated backward Raman scattering (SRS). In
this work, the influence of a super-Gaussian EEDF on the nonlinear evolution of
SRS is investigated by three wave model simulation and Vlasov-Maxwell
simulation for plasma parameters covering a wide range of k{\lambda}De from
0.19 to 0.48 at both high and low intensity laser drives. In the early-stage of
SRS evolution, it is found that besides the kinetic effects due to electron
trapping [Phys. Plasmas 25, 100702 (2018)], the Langdon effect can also
significantly widen the parameter range for the absolute growth of SRS, and the
time for the absolute SRS to reach saturation is greatly shorten by Langdon
effect within certain parameter region. In the late-stage of SRS, when
secondary instabilities such as decay of the electron plasma wave to beam
acoustic modes, rescattering, and Langmuir decay instability become important,
the Langdon effect can influence the reflectivity of SRS by affecting the
secondary processes. The comprehension of Langdon effect on nonlinear evolution
and saturation of SRS would contribute to a better understanding and prediction
of SRS in inertial confinement fusion.
