Impurity behaviour during ion Bernstein wave heating in the PBX-M tokamak

Ion Bernstein wave heating (IBWH) is used in the PBX-M tokamak to investigate active control of the pressure profile. A series of experiments was carried out to study impurity behaviour during IBWH under various discharge conditions. In all cases, impurity concentration increased and impurity transport was affected by application of IBWH. Core particle confinement was found to rise during IBWH, which resulted in an increase in the inward convective flow of impurities. Real time boronization of the vacuum vessel was successful in decreasing the overall impurity concentration.