ECRH and ECE in high Te, low density plasmas of LHD
The central electron temperature of more than 15 keV is achieved in LHD as a result of increasing the injection power and the lowering the electron density. Such collision-less regime is important from the aspect of the neoclassical transport and also potential structure formation. The creation of the high energy electrons and the transport of them can trigger the potential structure formation. Evidences of the presence of high energy electrons are indicated from hard X-ray PHA, and the discrepancy between the stored energy and kinetic energy estimated from Thomson scattering. ECE spectrum in such low density regime under the presence of high energy electrons are discussed by comparing the calculated one that solves the radiation transfer equation. Such investigation might be used for the estimation of high energy electrons as an inverse process of the ECRH.
