Effect of Energetic‐Ion‐Driven MHD Instabilities on Energetic‐Ion‐Transport in Compact Helical System and Large Helical Device

Abstract

Abstract This paper describes 1) representative results on excitation of energetic‐particle mode (EPM) and toroidicity‐induced Alfvén eigenmode (TAE) and consequent beam‐ion losses in CHS, and 2) recent results on beam‐ion transport and/or losses while EPMs are destabilized in LHD. Bursting EPMs and TAEs are often excited by co‐injected beam ions in the high‐beam ion pressure environment and give a significant effect on co‐going beam ions in both experiments. It seems that in CHS, resonant beam ions are lost within a relatively short‐time scale once they are anomalously transported due to energetic‐ion driven MHD modes, whereas unlike CHS, redistribution of beam ions due to energetic‐ion driven MHD modes is seen in LHD, suggesting that not all anomalously transported beam ions escape from the plasma (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)