Temperature fluctuation measurements with ECE on W7-AS

Electron temperature fluctuations at a relative level of the order of 0.1% in the presence of strong inherent intensity fluctuations of thermal radiation can be measured applying correlation radiometry of electron cyclotron emission. The diagnostic problem and the technique are briefly reviewed. Examples are given which characterize the temperature fluctuations as measured in the core region of purely ECRH heated plasmas with respect to spectrum, relative level, and coherence length. Parameter dependences are discussed. (author)