Line integrated density measurements based on Cotton–Mouton polarimetry

Abstract

A polarimeter based on the Cotton–Mouton effect has been developed and installed at the W7-AS stellarator. It is operated in the submillimeter wave region at frequencies of 500–650 GHz. The polarimeter demonstrated its capability to perform absolute, robust measurements of the line integrated electron density. The change of the state of polarization is calculated with high accuracy using Segre’s formalism. By varying the frequency and the B field, it could be shown that the Faraday effect has negligible influence on the measurements.