Status of steady-state magnetic diagnostic for ITER and outlook for possible materials of Hall sensors for DEMO

Abstract

The ITER outer vessel steady state (OVSS) magnetic diagnostic employing bismuth Hall sensors is presently being manufactured. New results on understanding and analytical description of a rather complex dependence of bismuth Hall coefficient on magnetic field and temperature are presented. Both, dependence of bismuth Hall coefficient on temperature and magnetic field is captured by a single analytical function while the error of the fit is comparable to the maximum allowed error of the ITER OVSS diagnostic. Results of FISPACT simulation of indium transmutation under ITER OVSS like neutron fluence are presented. Indium is used within OVSS sensors to provide periodic in-situ recalibration of embedded thermocouples. It is demonstrated that additional impurities introduced by indium transmutation does not compromise precision of the ITER OVSS diagnostic. Finally, outlook for Hall sensing materials (InAs, Bi, BiCu, Sb, Au-nanofilms, and graphene) potentially applicable for DEMO steady state sensors is given reviewing their properties in relation to the harsh environmental constraints posed to their implementation on DEMO reactor.