  The development of one-dimensional parametric instabilities of intense
long-wave plasma waves is considered in terms of the so-called hybrid models,
when electrons are treated as a fluid and ions are regarded as particles. The
analysis is performed for both cases when the average plasma field energy is
lower (Zakharov's hybrid model -- ZHM) or greater (Silin's hybrid model -- SHM)
than the plasma thermal energy. The efficiency of energy transfer to ions and
to ion perturbations under the development of the instability is considered for
various values of electron-to-ion mass ratios. The energy of low-frequency (LF)
oscillations (ion-sound waves) is found to be much lower than the final ion
kinetic energy. We also discuss the influence of the changes in the damping
rate of the high-frequency (HF) field on the instability development. Reduced
absorption of the HF field leads to the retardation of the HF field burnout
within plasma density cavities and to the broadening of the HF spectrum. At the
same time, the ion velocity distribution tends to the normal distribution in
both ZHM and SHM.
