A new multi-tracer pellet injection for a simultaneous study of low- and mid/high-Z impurities in high-temperature plasmas

Abstract

A new multi-tracer technique in the Tracer-Encapsulated Solid Pellet (TESPEL) method has been developed in order to acquire simultaneously the information about the behaviors of various impurities, i.e., to study concurrently the behaviors of low-and mid/high-Z impurities in magnetically confined high-temperature plasmas. In this new technique, an inorganic compound (for example, lithium titanate, Li 2 TiO 3 ) is proposed to be used as a tracer embedded in the core of the TESPEL, instead of pure elements. The results of the proof-ofprinciple experiment clearly demonstrate the applicability of the new multi-tracer technique in the TESPEL method for the simultaneous study of behaviors of low-and mid/high-Z impurities in high-temperature plasmas.

Development of a double-barreled Tracer Encapsulated Solid Pellet (TESPEL) injection system for LHD

“…And, compared to the LBO, many more various impurities can be injected into the plasmas utilizing the TESPEL. It should be noted here that it is technically possible to embed pure elements [8] or compounds [9] in the TESPEL as long as they are solid. Therefore, we believe that if we can inject multiple TESPELs in a single discharge, we could make significant progress in the study of impurity transport in the core region of the confined plasmas.…”