  The effects of a frequency-modulated pump on stimulated Brillouin scattering
(SBS) in a flowing plasma are investigated by theoretical analysis, three-wave
simulations, and kinetic simulations. The resonance point of SBS oscillates in
a certain spatial region with time when frequency modulations are applied.
There exists a certain frequency modulation that causes the velocity of
resonant points to be similar to the group velocity of the seed laser, which
increases the SBS reflectivity. The SBS can also be suppressed by frequency
modulation with larger bandwidth. In the kinetic simulations, the effects of
the frequency-modulated pump on the reflectivity agree with our theoretical
predictions. Multi-location autoresonance is also observed in the
narrow-bandwidth frequency modulation case, which can also increase the SBS
reflectivity. Our work provides a method for selecting the laser bandwidth to
inhibit SBS in inhomogeneous plasmas.
