Weak langmuir turbulence of an isothermal plasma

The aim of the paper is to study the Langmuir turbulence of plasma in the case where the scattering of Langmuir oscillations on plasma ions is the main mechanism of its non-linear interaction. This mechanism plays a determining part in an isothermal plasma at not too great turbulence intensities (TI). The one-dimensional model based on the jet stability is used in the work. It is shown that the one-dimensional jets in k vector-space, which arise in most cases of Langmuir wave excitation, usually have a fine structure in the form of intensity oscillations. The jets break down into chains of discreate peaks at a narrow spectral increment of instability taking place in parametric wave excitation. Localized excitations - solitons- may spread both along the jet and along the chain of peaks. A non-stationary regime takes place at not very small TI; Langmuir plasmons have no time to decay on account of collisions; their condensation into states with k=0 and subsequent development of Langmuir collapse (LC) occur. The spectrum, which is non-stationary in this case, consists of moving solitons absorbed by the LC mechanism. It is noted that two LC regimes are possible depending on the LC intensity: subsonic and supersonic. Plasma heating by a relativistic electron beam is considered as an example. A series of numerical experiments have been carried out to verify the analytic solution. The results obtained show that the one-dimensional approximation adequately describes