EXCITATION OF ION-SOUND FLUCTUATIONS IN A MAGNETIZED PLASMA WITH STRONG LANGMUIR TURBULENCE

In the presence of the strong Langmuir turbulence excited by a high-po wer relativistic electron beam (E = 700 keV, j = 1.5 kA/cm(2), tau = 2 00 ns), the energy density of ion-sound fluctuations in a nonisotherma l magnetized plasma (n(e) similar to 10(15) cm(-3), T-e much greater t han T-i) is measured. The turbulence is studied by laser scattering (C O2 laser, E = 10 J, lambda = 10.288 mu m). It is shown that the spectr al energy density of ion-sound oscillations substantially exceeds the thermal level (W-k/T-e approximate to 10(5)). From the k spectrum of i on-sound fluctuations, the upper limit for the minimum dimension of co llapsing cavities, l(min) < 30r(D), is found.