The Electrostatic Turbulence of Edge Plasma under Electron Cyclotron Resonance Heating in NCST

Understanding the laws of confinement and transport of plasma at high electron temperature is a key issue in the field of plasma fusion research. The turbulent transport level of edge plasma is studied by using the Langmuir probe in NanChang Spherical Tokamak (NCST). The results show that electron heat conduction dominated by temperature diffusion due to temperature gradient occupies the center of the energy flow in the scrape-off layer (SOL) of NCST. In addition, it is observed that the contribution of electron heat convection resulting from the electron transport process gradually increases during the discharge process, with the ratio of electron thermal convection and electron thermal conduction increasing from about 15 to 44%. The study of different fueling methods found that the gas-fueling efficiency and disturbance of secondary gas-fueling using supersonic molecular beam injection (SMBI) are stronger than those using gas puffing (GP). It indicates that the SMBI is more suitable for supplementing gas during the discharge.