摘要
Impurity transports in two neighboring discharges with and without electron cyclotron resonance heating（ECRH）are studied in the HL-2A tokamak by laser blow-off（LBO） technique.The progression of aluminium ions as the trace impurity is monitored by soft x-ray（SXR） and bolometer detector arrays with good temporal and spatial resolutions.Obvious difference in the time trace of the signal between the Ohmic and ECRH L-mode discharges is observed.Based on the numerical simulation with one-dimensional（1D） impurity transport code STRAHL,the radial profiles of impurity diffusion coefficient D and convective velocity V are obtained for each shot.The result shows that the diffusion coefficient D significantly increases throughout the plasma minor radius for the ECRH case with respect to the Ohmic case,and that the convection velocity V changes from negative（inward） for the Ohmic case to partially positive（outward） for the ECRH case.The result on HL-2A confirms the pump out effect of ECRH on impurity profile as reported on various other devices.
Impurity transports in two neighboring discharges with and without electron cyclotron resonance heating（ECRH）are studied in the HL-2A tokamak by laser blow-off（LBO） technique.The progression of aluminium ions as the trace impurity is monitored by soft x-ray（SXR） and bolometer detector arrays with good temporal and spatial resolutions.Obvious difference in the time trace of the signal between the Ohmic and ECRH L-mode discharges is observed.Based on the numerical simulation with one-dimensional（1D） impurity transport code STRAHL,the radial profiles of impurity diffusion coefficient D and convective velocity V are obtained for each shot.The result shows that the diffusion coefficient D significantly increases throughout the plasma minor radius for the ECRH case with respect to the Ohmic case,and that the convection velocity V changes from negative（inward） for the Ohmic case to partially positive（outward） for the ECRH case.The result on HL-2A confirms the pump out effect of ECRH on impurity profile as reported on various other devices.
基金
Project partly supported by the National Natural Science Foundation of China(Grant Nos.11375057 and 11175061)
the Chinese National Magnetic Confinement Fusion Science Program(Grant No.2014GB108003)
