Experiments on Physics Issues in Burning Plasma: Isotope Mixing and Ion Collisionless Energy Transfer

Abstract Experiments on physics issues in burning plasma were conducted in the deuterium campaign of Large Helical Devices (LHD). One is an isotope mixing experiment, and the other is the collisionless energy transfer from energetic particles to bulk ions.The important finding for ion mixing in the LHD experiment is that the ITG turbulence (but not TEM turbulence) contributes to the isotope and ion mixing, which is beneficial for controlling the isotope ratio (deuterium and tritium) and helium ash exhaust. The experimental identification of energy transfer from energetic particles to bulk ions through Landau damping and transit-time damping suggests a possible ion-heating process for the ion-ITB plasma with (T i /T e > 1) through collisionless energy transfer from alpha particles to bulk ions through energetic particle-driven instability, so-called alpha channeling.