Improvement of fusion reactivity and fusion power multiplication factor in the presence of fast ions

Abstract

Improvement of fusion reactivity (〈σv〉) and fusion power multiplication factor ( Q) in the presence of fast ions has been investigated with the analytical solution of the velocity distribution function. Fast ions created by only NBI heating, only ICRF heating and a combination of NBI and ICRF heating are considered in a D-T plasma. The dependences of 〈σv〉 on the plasma temperature, the deposited power density, the electron density and the injected beam energy are clarified. Calculations of evaluating Q employ a simple plasma model in which the radial profiles of the plasma temperature and density are the same as those observed in recent experiments. 〈σv〉 and Q are enhanced by only NBI heating, the combined NBI and ICRF heating and only ICRF heating in this order under the same heating power. However, the increase in 〈σv〉 and Q for the former two methods is almost the same. In the presence of fast ions, the enhancement of 〈σv〉 and Q is larger than the increase in the plasma pressure.