Effect of isotope mass on transport simulations of Joint European Torus high-mode plasmas with Edge Localized Modes

The effect of isotopic mass on heat and particle transport in Joint European Torus (JET) [P.-H. Rebut , Nucl. Fusion 25, 1011 (1985)] plasma discharges is studied using the Multi-Mode model in the BALDUR predictive transport code [Bateman , Phys. Plasmas 5, 1793 (1998)]. Temperature and density profiles from these simulations generally agree with the experimentally measured profiles for high-mode JET discharges with Edge Localized Modes in hydrogen, deuterium, and tritium discharges. It is surprising that a purely gyro-Bohm transport model, used in these simulations, correctly predicts the experimentally observed improvement in confinement as the isotope mass is increased-given the fact that gyro-Bohm diffusion coefficients increase with isotope mass when the shapes of all the plasma profiles are held fixed. However, in the JET experiment, it was found that the electron and ion temperature at the top of the edge pedestal increases systematically as the isotope mass in increased (J. G. Cordey , Report No. JET-P (98)53, 1998). The numerical simulations reported here show that this increase in the edge temperatures and subsequent broadening of the temperature profiles account for the improvement in confinement as the isotope mass is increased. (C) 1999 American Institute of Physics. [S1070-664X(99)00112-3].