A nonlinear fluid description for the parameter processes has been der
ived. The linear instability analyses about three wave mixing process
w(0) --> w,(1) + w,(2) and four wave scattering process w(0) --> w(s)
+ w(p1) + w(p2) have been made. Correspondent backward or side scatter
ing light waves emitted from mentioned processes may provide valuable
information for the diagnostic of plasma parameters.