Experimental evidence for electron temperature fluctuations in the core plasma of the W7-AS stellarator

Correlation radiometry has been applied to detect for the first time electron temperature fluctuations in the core of a magnetically confined plasma by means of electron cyclotron emission. Broadband fluctuations are observed in the frequency range up to 150 kHz with levels below 1.4%. Apparent temperature fluctuations due to the finite optical depth are subtracted; the remaining electron temperature fluctuation level is significant. On the basis of reasonable considerations, the results indicate that electron temperature fluctuations can contribute to the anomalous electron heat flux.