Self-consistent simulations of the interaction between fusion-born alpha particles and lower hybrid waves in ITER

Abstract

In order to control the plasma current profile, it might be necessary to apply lower hybrid waves in ITER and future fusion reactors, since they are capable of generating off-axis current. However, the efficiency of the lower hybrid current drive may be affected by parasitic absorption by fusion-born alpha particles. In order to quantify this absorption, a consistent coupling has been established between (i) the DELPHINE code which calculates the LH wave propagation and absorption on electrons and alpha particles and (ii) the SPOT orbit following Monte Carlo code augmented with an operator accounting for the interaction between fast ions and radio-frequency waves. The LH wave absorption in the ITER steady-state reference scenario 4 (ITER Technical Basis 2002 ITER EDA Documentation Series No 24, Report G A0 FDR 1 01-07-13 R1.0) has been analysed for the LH source frequencies of 5 and 3.7 GHz. Results indicate that the alpha parasitic absorption is weak for both cases: 0.08% and less than 3% for 5 GHz and 3.7 GHz, respectively.