Relativistic effect on synergy of electron cyclotron and lower hybrid waves on EAST

In recent experiments on EAST, the electron temperature at the center can be raised to 9.7 keV by injecting electron cyclotron (EC) and lower hybrid (LH) waves simultaneously. With such strong core electron heating, the relativistic effect could play an important role in the interactions between the plasma and waves. In order to explore the relativistic effect on synergy between the EC and LH waves on EAST, ray-tracing/Fokker-Planck simulations are conducted to investigate electron heating for a typical discharge with a center electron temperature of 9.7 keV. It is found that the relativistic effect can cause the EC wave to deposit its power deeper in the plasma core, where the synergy between the EC and LH waves occurs and enhances the absorption of the LH waves. As a result, a high center electron temperature can be achieved.