Results from prototype polarimeter/interferometer on Alcator C-Mod

Abstract

The poloidal field and corresponding toroidal current profiles have been among the most difficult and most important measurements in tokamak fusion research. One method demonstrated to obtain information about these quantities is polarimetry, in which Faraday rotation caused by the plasma is measured. Design has begun for a 20-channel, Far-infrared polarimeter-interferometer system on Alcator C-Mod. In preparation for this experiment, a poloidally-viewing prototype polarimeter-interferometer has been constructed, installed, and tested on Alcator C-Mod. This thesis describes the design of this prototype and reports the results obtained, with emphasis on those applicable to the future polarimeter-interferometer. Specifically, experimental techniques and alignment procedures, sensitivity to vibration, and conditions affecting reflection from the inner wall are explored.