Improvement of confinement by lower hybrid waves

Quasi-steady-state H-mode has been achieved by combination of two lower hyb rid waves in HT-6M tokamak. Plasma energy confinement time increases by two times,and the particle confinement time increases by a factor of three und er a high plasma density condition. The wave diffusion and current radial d iffusion code is used to simulate the experimental data on HT-6M. The calcu lated results show that the off-axis power deposition of lower hybrid wave is formed due to the low toroidal magnetic field and high plasma density. R eversed sheared(RS) configuration of the plasma current density is formed d uring H-mode phase. The RS configuration and internal transport barrier are attributed to the enhanced confinement improvement. The experimental data also gives the evidence for the reversed shear formation.