First Results of Collective Thomson Scattering Diagnostic of Fast Ions at the GDT Open Magnetic Trap

Fast-ion diagnostic based on measuring of the collective Thomson scattering of high-power gyrotron radiation has been developed for the gasdynamic trap facility in Budker Institute during the last 3 years. This diagnostic is aimed at reconstruction of ion distributions over transverse and longitudinal velocities driven in the plasma core by strong neutral beam injection. Here, we present the first experimental results which may be interpreted as the expected scattering signal from fast ions. The detected spectra with the effective noise temperature of about 100 eV detuned in a particular frequency range of 100–300 MHz from the probe gyrotron frequency are compatible with the early theoretical predictions.