ION ACOUSTIC PARAMETRIC DECAY INSTABILITIES WITH STRONG ION LANDAU DAMPING

i-UNCLASSIFIED (Lll B.uip./u^ ^ 1, kM/k>1) excite plasma wave are reporteB. Two basi investigated, one where the pump wa W mstHF^^) (electromagnetic excitat SECURITY CLASSIFiCATIQN OF T^.S PAQEr^.w D... B„,.„d; wavelength is finite, ^irkf-d by an m«0 Gould-Trivelpiece c excitation regimes are velength is very long, ion) and one where the pump Ü, (electrostatic excitation). Foi electromagnetic excitation, instabilxty threshold and instabili were measured and found to be in ag However, measured saturated instabi stronger pump intensity dependence saturation theories, and are in qua predicted dependences based on equi density dependence of ty threshold frequency shift reement with expectations, lity intensities show a much than predictea by nonlinear litative agreement with librium changes. wavelenot^fnv0*^1 ^ excitation, measurements of frequency and:r««onw?r£.cc^nnr,d the m"sured <'^pe"iönc)'reoLcj1ijna"on