Burning Plasma Physics Issues Illustrated by Simulations of Fire

Plasma startup and operating issues are examined for a burning plasma using WHIST [1] simulations of the Fusion Ignition Research Experiment (FIRE) design [2]. Fueling and density profile control issues are illustrated through pellet launch from the inboard side of the plasma. Auxiliary fast wave ion cyclotron heating and current drive are used to identify plasma startup and burn control issues. It is shown that the current rampup and bootstrap current strongly influence the evolution of the safety factor, and can be tailored to produce sawtooth-free operation for about 20 seconds of burn in well-confined high confinement mode (Hmode) plasmas. Furthermore, it is also possible to maintain a reversed magnetic configuration that could allow access to the improved core confinement seen in present experiments. Access to H-mode operation is influenced by the fueling, heating and current startup waveforms. Maintenance of H-mode conditions may require either hysterisis in the high to low confinement (H-L) back-transition or continued auxiliary heating if the fusion power is insufficient.