Abstract: We analyze effect of a small-bandwidth linear frequency chirp on growth of Raman instability with coupled relativistic Maxwell-fluid equations.It is shown that threshold of Raman backward scattering is increased by frequency chirp with no dependence on the sign of chirp.And growth rate of Raman forward scattering increases(decreases) for a positive(negative) chirp.In addition 1D3V particle-in-cell simulations are performed.It shows agreement with theoretical analysis.

Key words: stimulated Raman scattering, frequency chirp, particle-in-cell simulation