DT fusion power production in ELM free H modes in JET

摘要

Experiments in the ELM free hot ion H mode regime have been carried out in DT plasmas in JET. Initial experiments undertaken at constant neutral beam (NB) power (～11 MW) demon- strated that core fuelling was dominated by wall/target recycling rather than NB fuelling and made it possible to arrange an optimum core DT mix by adjusting the DT mix in wall/target, gas and NB. High power experiments at 4.2 MA/3.6 T have successfully and reliably delivered fusion power (P_fus) up to 16.1 MW and plasma stored energy (W_dia) up to 17 MJ. The results are in good agree- ment with extrapolations, carried out with the TRANSP and JETTO codes, from similar deuterium discharges. Transiently, values of Q_tot up to 0.95 ± 0.17 were achieved, consistent with values of n_DT(0)τ_E, _diaT_i(0) ≈ 8.7× 10~20 m~(-3)·s·keV± 20%. The ratio of fusion power to input power, Q_in, is in excess of 0.6. There are indications of an isotope effect on the edge pressure pedestal, but no net dependence of global confinement on isotopic plasma composition has been found.