Using lower hybrid current drive (LHCD), improved confinement has been achieved on HT-6B tokamak. The particle confinement time was increased by 2- 6 times and the plasma-stored energy was doubled. Only obtainable in ...Using lower hybrid current drive (LHCD), improved confinement has been achieved on HT-6B tokamak. The particle confinement time was increased by 2- 6 times and the plasma-stored energy was doubled. Only obtainable in an electron density window of 0.3×1013- 1.5× 1013cm-3, the improvement was accompanied by suppression of the fast fluctuations and increment of the gradient of edge electron temperature with very low power threshold. An analysis shows that the improvement might be possibly caused by certain energetic electrons produced by LHCD.展开更多
A cylindrical carbon pellet with a size of 1.2L x 1.2φ mm to 1.8L x 1.8φ mm and a velocity of 100 m/s to 300 m/s was injected into large helical device （LHD） for an efficient fueling based on its deeper deposition...A cylindrical carbon pellet with a size of 1.2L x 1.2φ mm to 1.8L x 1.8φ mm and a velocity of 100 m/s to 300 m/s was injected into large helical device （LHD） for an efficient fueling based on its deeper deposition instead of hydrogen gas puffing and ice pellet injection. Electron density increment of Ane = 10^14 cm^-3 is successfully obtained by single carbon pellet injection without plasma collapse. Typical density and temperature of the ablation plasma of the carbon pellet, e.g., 6.5× 10^16 cm^-3 and 2.5 eV for CII, are examined respectively by spectroscopic method. A confinement improvement up to 50% compared to ISS-95 stellarator scaling is clearly observed in a relatively low-density regime of ne = 2 × 10^13 cm^-3 to 4×10^13 cm^-3, and high ion temperature Ti（0） of about 6 keV is also observed with an internal transport barrier at ne = 1.2 × 10^13 cm^-3. In particular, the improvement in the ion temperature largely exceeds that observed in hydrogen gas-puffed discharges, which typically ranges below 3 keV.展开更多
文摘Using lower hybrid current drive (LHCD), improved confinement has been achieved on HT-6B tokamak. The particle confinement time was increased by 2- 6 times and the plasma-stored energy was doubled. Only obtainable in an electron density window of 0.3×1013- 1.5× 1013cm-3, the improvement was accompanied by suppression of the fast fluctuations and increment of the gradient of edge electron temperature with very low power threshold. An analysis shows that the improvement might be possibly caused by certain energetic electrons produced by LHCD.
文摘A cylindrical carbon pellet with a size of 1.2L x 1.2φ mm to 1.8L x 1.8φ mm and a velocity of 100 m/s to 300 m/s was injected into large helical device （LHD） for an efficient fueling based on its deeper deposition instead of hydrogen gas puffing and ice pellet injection. Electron density increment of Ane = 10^14 cm^-3 is successfully obtained by single carbon pellet injection without plasma collapse. Typical density and temperature of the ablation plasma of the carbon pellet, e.g., 6.5× 10^16 cm^-3 and 2.5 eV for CII, are examined respectively by spectroscopic method. A confinement improvement up to 50% compared to ISS-95 stellarator scaling is clearly observed in a relatively low-density regime of ne = 2 × 10^13 cm^-3 to 4×10^13 cm^-3, and high ion temperature Ti（0） of about 6 keV is also observed with an internal transport barrier at ne = 1.2 × 10^13 cm^-3. In particular, the improvement in the ion temperature largely exceeds that observed in hydrogen gas-puffed discharges, which typically ranges below 3 keV.
