DIAGNOSTICS OF DENSITY-FLUCTUATIONS BY ENHANCED SCATTERING WITH FREQUENCY-TUNABLE MICROWAVE SOURCES

The enhanced scattering diagnostics method based on the scattering of microwaves close to the upper hybrid resonance in the plasma has a hig h sensitivity and spatial resolution and makes it possible to observe the plasma density fluctuations with characteristic scale-lengths much smaller than the wavelength of the probing radiation in vacuum. Good spatial resolution for spatial positioning of the scattering volume by fast tuning of the source frequency +/-5% around the reference freque ncy in the range 100 - 300 GHz; at high power makes this diagnostic me thod particularly suitable for fluctuation and high energy particle me asurements in tokamak plasmas with relatively flat density and tempera ture profiles.