Conceptual design of high resolution and reliable density measurement system on helical reactor FFHR-d1 and demonstration on LHD

摘要

This paper describes a conceptual design of the density measurement system on the helical reactor FFHR-d1 based upon its quantitative operation scenario. The density measurement is necessary to satisfy the reactor design, and to have a high density resolution of the order of 10~(17) m~(-3) with a time resolution of 10ms. High reliability that avoids measurement failures is also necessary. A combined system of 'a dispersion interferometer' and a polarimeter is designed and a prototype of the dispersion interferometer with an Nd:YAG laser is tested. The dispersion interferometer with a CO_2 laser is also installed on LHD, which can realize a demo relevant density plasma. The prototypes demonstrate the feasibility on a demo reactor.