WAVE-PARTICLE RESONANCE IN MAGNETIZED PLASMA

We report the first observation of the wave-particle resonance line in a magnetized and weakly collisional plasma. The linear resonance sati sfies the relation omega - n Omega(ci) = k(parallel to)v(parallel to) and has a width which is related to the wave-particle coherence time. Both the in-phase (real) and quadrature (imaginary) parts of the reson ant response are directly determined by a phased-lock laser induced fl uorescence diagnostic. The wave-particle coherence time obtained by fi tting the resonance line shape to a one-dimensional Poisson-Fokker-Pla nck model does not agree with a simple model of ion collisionality.