Improvement of plasma confinement with lower hybrid current drive on HT-6B tokamak

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.