The time-delay of a microwave signal, backscattered at the hybrid resonance and new possibilities for the diagnostics of small scale plasma fluctuations

Enhanced scattering (ES) is a diagnostics, based on backscattering close to a hybrid resonance layer. Compared with conventional collective scattering, ES ''sees'' fluctuations with much smaller scale-lengths and produces much more strong signals. In addition, it provides automatically fairly good spatial resolution of measurements. However, the wave-vector resolution here is intrinsically poor because both incident KI and scattered KS wave-vectors have a rapid variation in the resonance region and the matching conditions 2K(x)=q with K=KI=-KS can be satisfied in a wide interval of q. Here q is the fluctuation wave-vector and we suppose for simplicity that all waves propagate along the plasma inhomogeneity direction. A radar-like modification of ES using the time of flight analysis to cope with this problem is presented in this report. (author) 3 refs., 4 figs