X-ray Observations between 10 and 150 keV from the Alcator C Tokamak

78ET51013. Reproduction, translation, publication, use and disposal, in whole or in part by or for the United States government is permitted. By acceptance of this article, the publisher and/or recipient acknowledges the U. S. Govern-ment's right to retain a non-exclusive, royalty-free license in and to any copyright covering this paper. X-ray Observations between 10 and 150 keV from the Alcator C Tokamak J.E.Rice and K. L.Chamberlain Plasma Fusion Center MIT A mercuric iodide (HgI2) detector has been used to obtain x-ray spectra in the en-ergy range from 5 to 200 keV from the Alcator C tokamak. During high density ohmic operation of Alcator C, this detection system provides a reliable electron temperature di-agnostic. Non-thermal x-ray spectra above 20 keV are observed under certain conditions when a substantial amount of LHRF power is injected. The magnitude of this non-thermal behaviour strongly increases as the electron density is lowered and is more pronounced in deuterium plasmas than in hydrogen. Model electron distribution functions, which can give rise to the observed x-ray spectra, are discussed. I