Parametric backscattering and absorptive instabilities in homogeneous unmagnetized plasmas

The paper considers the two scattering instabilities photon decays into photon plus plasmon ( t → t' + l ) and photon decays into photon plus phonon (t → t' + s) and the two absorptive instabilities photon decays into plasmon plus plasmon (t → l + l' ) and photon decays into plasmon plus phonon (t → l + s) . The corresponding growth rates and thresholds are determined for a homogeneous, unmagnetized plasma. The regimes of weak and moderately strong pump fields are examined, together with the possibility of purely-growing instabilities for the decays t → t' + s and t→ l + s .