DIAGNOSTICS OF PLASMA FLUCTUATIONS BY CO2-LASER COLLECTIVE SCATTERINGWITH A MULTICHANNEL ANGULAR ANALYSIS OF SCATTERED RADIATION

A new CO2-laser collective scattering diagnostic technique is develope d and used for studying plasma microturbulence during the transition t o improved plasma confinement or the transition from the lower-hybrid current drive to the plasma heating regime in the FT-2 tokamak. The di agnostics provide simultaneous measurements of radiation scattered by fluctuations of four different scales. The conception and basic parame ters of the diagnostics are discussed. The results of measurements car ried out in the FT-2 tokamak show the feasibility of this diagnostic t echnique. It is shown that multichannel angular analysis of scattered radiation allows observation of new features of small-scale fluctuatio ns.