Alpha particle loss in TFTR deuterium-tritium plasmas with reversed magnetic shear

摘要

The confinement and loss of fusion alpha particles are examined for reversed magnetic shear plasmas in TFTR. Such plasmas, with high central q and non-monotonic q profiles can exhibit remarkably reduced energy and particle transport of the thermal ions. However, these same conditions are theoretically predicted to produce high levels of stochastic ripple loss of suprathermal particles, which may reduce the efficiency of plasma heating by the alpha particles and other heating schemes involving fast ions. This paper presents calculations of guiding-center code alpha particle orbit loss from deuterium- tritium (DT) simulations of TFTR deuterium-only experiments. They are compared to results of measurements made in DT reversed shear plasmas of both the confined alpha particle distribution and the alpha particles lost from the plasma. Large fast particle losses have also been found in reversed shear ITER simulations (up to 20%) and from measurements of triton burnup in reversed shear experiments on JT-60U (12%).