Development of advanced collective thomson scattering for impurity, helium ash density, and D/T ratio measurements

Measurements of impurity concentration, helium ash density, and D/T fuel ratio are among the most important diagnoses for assessing the core region of burning plasmas. However, diagnostic method useful for these measurements has not yet been established. In order to realize such measurements, an advanced technique using collective Thomson scattering has been proposed [S. Lee and T. Kondoh, Rev. Sci. Instrum. 71, 3718 (2000)]. This article presents the conceptual design of this technique and the calculated results of a scattered spectrum associated with the ITER FEAT plasma. The experimental requirements for measuring a scattered spectrum resulting from ion cyclotron oscillations are discussed in detail. The possibility of proof-of-principle for this method in JT-60U and LHD plasmas is also considered. (author)