H-mode operation in helium plasma with tungsten divertor and low input torque in EAST

To support the ITER early non-nuclear operational phase, recent helium experiments have been investigated intensively in the superconducting tokamak EAST equipped with ITER-like Tungsten divertor, under the condition of low injected torque. This paper demonstrates experimental observations from these experiments. In particular, we report the impact of helium concentration on the L-H transition power threshold, energy confinement, and the ELM behavior. Dependences of L-H threshold on electron density, plasma current and magnetic field are also discussed. (paper)