We report on current profile evolution in EAST NBI driven plasmas where two neutral beams are injected,one during the current ramp phase and the second during flattop.At the end of the current ramp phase,it is found t...We report on current profile evolution in EAST NBI driven plasmas where two neutral beams are injected,one during the current ramp phase and the second during flattop.At the end of the current ramp phase,it is found that a flat q profile with q0-1 is achieved with low magnetic shear in the core.It is observed that plasma current and density both relax much faster than resistive time,even in the absence of sawtooth activity when H-L transition occurs.Density fluctuations associated with magnetic perturbations（3/2） as a precursor to the H-L transition are observed.It is likely that these modes play a role in fast current transport.展开更多
基金supported by National Key R&D Program of China,contract No.2014GB106002partly supported by the US D.O.E.contract DESC0010469partly supported by the Major Program of Development Foundation of Hefei Center for Physical Science and Technology with contract No.2016FXZY007
文摘We report on current profile evolution in EAST NBI driven plasmas where two neutral beams are injected,one during the current ramp phase and the second during flattop.At the end of the current ramp phase,it is found that a flat q profile with q0-1 is achieved with low magnetic shear in the core.It is observed that plasma current and density both relax much faster than resistive time,even in the absence of sawtooth activity when H-L transition occurs.Density fluctuations associated with magnetic perturbations（3/2） as a precursor to the H-L transition are observed.It is likely that these modes play a role in fast current transport.
