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.
We apply the well-known concept of spontaneous and stimulated emission to some nonlinear processes in plasma. The consideration of beam–plasma instability in this approach allows us not only to obtain an increment of the instability and other important characteristics by a non-traditional method but also to study in detail the initial stage of the instability, when a noise caused by spontaneous emission has a great influence on further dynamics of the system. Another interesting example of the considered method is the three-wave interaction of ion-sonic waves in plasma. We have shown that oscillations generated by nonlinear currents at combined frequencies demonstrate all the characteristics of spontaneous and stimulated emission. In both cases, we derived the equations for the intensity of emitting waves in a form that is similar to equations obtained in the traditional theory of spontaneous and stimulated emission.
dispertion law, a nonlinearity saturation e. t. c. I , which may be very significant in the finish stage collapse dynamics.-The estimate follows from the "improved" equations shows that t h e some of higher order nonlinearities become essential at WmT < 1, Ck rd2 < 1.-In the frame work of analysis of linear stage of the instability the influence of these nonlinearities on the instability increment is established. 2P18 SURFACE cYcx".m UKS O>i PLASMA -METAL BJ'JNZRY GIFKA v. A. , PAYLE>CC r. v. Kharkiv State University. Svobvdy T I E sq,,
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