ECE imaging of plasma Te profiles and fluctuations

A novel electron cyclotron emission (ECE) radiometry technique, Electron Cyclotron Emission Imaging (ECEI), has been developed and applied to the TEXT-U and RTP tokamaks for the study of electron temperature profiles and fluctuations. Instead of a single receiver located in the tokamak midplane as in conventional ECE radiometers, the ECEI systems utilized newly developed millimeter wave imaging arrays as the receiver/mixers. Combined with specially designed imaging optics, the use of these compact, low cost arrays has resulted in the excellent spatial resolution of the ECEI systems, the unique capability of two-dimensional measurements, and great flexibility in the measurement of plasma fluctuations. Technical details of the diagnostic are described in this paper, emphasizing the data for the RTP ECEI system. Illustrative experimental results are presented, together with a discussion of the further development of the diagnostic. (C) 2001 Elsevier Science B.V. All rights reserved