In the recent experiment on HT-6M tokamak,an improved ohmic confinement phase has been observed after application of the edge multi-pulse turbulent heating,and variance of plasma currentΔI_(p)/I_(p) is about 14-20%;....In the recent experiment on HT-6M tokamak,an improved ohmic confinement phase has been observed after application of the edge multi-pulse turbulent heating,and variance of plasma currentΔI_(p)/I_(p) is about 14-20%;.The improved edge plasma confinement phase is characterized by(a)increased average electron density N_(e) and electron temperature T_(e);(b)reduced Hαradiation from the edge;(c)steeper density and temperature profiles at the edge;(d)a more negative radial electric field over a region of~5mm deep inside the limiter;(e)a deeper electrostatic potential well at the edge;(f)reduced magnetic fluctuations at the edge.展开更多
Lower hybrid current drive experiments on the HT-7 device have been carried out by scanning the following parameters: central line averaged electron density (ne = 0.6 - 2.0 × 1019m-3) and toroidal magnetic field ...Lower hybrid current drive experiments on the HT-7 device have been carried out by scanning the following parameters: central line averaged electron density (ne = 0.6 - 2.0 × 1019m-3) and toroidal magnetic field (Bt = 1.62 - 2.0 T). The dependence of current drive efficiency on these parameters has been studied and the experimental curves of current drive efficiency as a function of ne and Bt have also been obtained. From these experimental results, it can be seen that current drive efficiency rises with the increase of toroidal magnetic field. As plasma density increases, the current drive efficiency first increases to a certain value, then gradually decreases, that is, there exists an optimized density regime where a better drive efficiency can be obtained. The analysis shows that the current drive efficiency is mainly affected by wave accessibility and impurity concentration, and the competition of these two factors determines the current drive efficiency.展开更多
Lower hybrid current drive(LHCD)experiments have been done on the superconducting Tokamak HT-7 by using a new developed long pulse megawatt lower hybrid wave system.An LHCD efficiency of 0.5×10^(19)A·m^(-2)/...Lower hybrid current drive(LHCD)experiments have been done on the superconducting Tokamak HT-7 by using a new developed long pulse megawatt lower hybrid wave system.An LHCD efficiency of 0.5×10^(19)A·m^(-2)/W in a pulse length of several hundreds of milliseconds has been achieved.After boronization of the tokamak vacuum vessel,considerable improvements of plasma energy confinement and particle confinement during LHCD phase have been achieved by adjusting wave spectra.An energy transfer from the lower hybrid wave to plasma bulk electrons has been demonstrated experimentally.A computer simulation of the LHCD experiments by using a ray tracing code combined with a two dimensional Fokker-Planck code is in good accordance with experimental measurements and suggests an important role of plasma current profile.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No,19675041.
文摘In the recent experiment on HT-6M tokamak,an improved ohmic confinement phase has been observed after application of the edge multi-pulse turbulent heating,and variance of plasma currentΔI_(p)/I_(p) is about 14-20%;.The improved edge plasma confinement phase is characterized by(a)increased average electron density N_(e) and electron temperature T_(e);(b)reduced Hαradiation from the edge;(c)steeper density and temperature profiles at the edge;(d)a more negative radial electric field over a region of~5mm deep inside the limiter;(e)a deeper electrostatic potential well at the edge;(f)reduced magnetic fluctuations at the edge.
文摘Lower hybrid current drive experiments on the HT-7 device have been carried out by scanning the following parameters: central line averaged electron density (ne = 0.6 - 2.0 × 1019m-3) and toroidal magnetic field (Bt = 1.62 - 2.0 T). The dependence of current drive efficiency on these parameters has been studied and the experimental curves of current drive efficiency as a function of ne and Bt have also been obtained. From these experimental results, it can be seen that current drive efficiency rises with the increase of toroidal magnetic field. As plasma density increases, the current drive efficiency first increases to a certain value, then gradually decreases, that is, there exists an optimized density regime where a better drive efficiency can be obtained. The analysis shows that the current drive efficiency is mainly affected by wave accessibility and impurity concentration, and the competition of these two factors determines the current drive efficiency.
文摘Lower hybrid current drive(LHCD)experiments have been done on the superconducting Tokamak HT-7 by using a new developed long pulse megawatt lower hybrid wave system.An LHCD efficiency of 0.5×10^(19)A·m^(-2)/W in a pulse length of several hundreds of milliseconds has been achieved.After boronization of the tokamak vacuum vessel,considerable improvements of plasma energy confinement and particle confinement during LHCD phase have been achieved by adjusting wave spectra.An energy transfer from the lower hybrid wave to plasma bulk electrons has been demonstrated experimentally.A computer simulation of the LHCD experiments by using a ray tracing code combined with a two dimensional Fokker-Planck code is in good accordance with experimental measurements and suggests an important role of plasma current profile.
