DENSITY FLUCTUATION EFFECTS ON ELECTRON-CYCLOTRON EMISSION CORRELATION-MEASUREMENTS IN OPTICALLY GRAY PLASMAS

Measurements of electron temperature using electron cyclotron emission (ECE) may be contaminated by density effects in plasmas with low opti cal depth. ECE intensity fluctuations in these plasmas will include a component dependent on density fluctuations as well. Correlation measu rements, which will extract the temperature fluctuations from the domi nant radiometer thermal noise, will include correlated density fluctua tions in the result. In tokamak core plasmas, where normalized density fluctuations have been measured to be about 1%, this effect can be co nsiderable (approximately 100%) at low levels of temperature fluctuati ons. However, at ''relevant'' levels, defined by the amount of anomalo us heat transport, these effects are reduced, at least in TEXT-U. Whil e exact interpretation of:temperature fluctuation amplitudes is compro mised, statements regarding the relevance of the inferred temperature fluctuation amplitudes can be made relatively unambiguously.