Advanced operation modes relying on core plasma turbulence stabilization in tokamak fusion devices

Abstract Recent progress of advanced operation modes in tokamaks is addressed focusing upon internal transport barrier (ITB) discharges. These ITB discharges are being considered as one of candidate operation modes in fusion reactors. Here, “internal” means core region of a fusion plasma, and “transport barrier” implies bifurcation of transport phenomena due to suppressing plasma turbulence. Although ITB discharges have been developed since the mid-1990, they have been suffering from harmful plasma instabilities, impurity accumulation, difficulty of feedback control of kinetic plasma profiles such as pressure or current density, and so on. Sustainment of these discharges in long-pulse operations above wall saturation time is another huddle. Recent advances in ITB experiments to overcome the difficulties of ITB discharges are addressed for high βp plasmas in DIII-D, broad ITB without inte…