Simulation of high ion temperature mode in JT-60

The high ion temperature mode in JT-60, where Ti above 10 keV were obtained by hydrogen beam heating of 20 MW into hydrogen limiter plasmas with IP = 1 ∼ 2 MA, is investigated by using the one dimensional transport code and experimental data of electron density and temperature. It is found that, in a low density plasma with high Zeff, the dilution of thermal ions due to impurities and fast ions produced by neutral beam injection causes rapid increase in the ion temperature. On the other hand, in the steady state, the dilution has little effect on the central ion temperature for fixed electron temperature because the convection loss is dominant. (author)