Anomalous current diffusion and improved confinement in the HT-6M tohamak

• Published in: Physics letters. A 1994-10, Vol.193 (4), p.397-402
• Main Authors: Gao, X., Li, J.G., Wan, Y.X., Huo, Y.P., Guo, W.K., Fan, S.P., Yu, C.X., Luo, J.R., Yin, F.X., Meng, Y.D., Zheng, L., Yin, F., Lin, B.L., Zhang, S.Y., Wang, S.Y., Lu, H.J., Liu, S.X., Tong, X.D., Ding, L.C., Wu, Z.Y., Yin, X.J., Guo, Q.L., Gong, X.Z., Wu, X.C., Zhao, J.Y., Xi, J.S.
• Format: Article
• Language: English
• ISSN: 0375-9601; 1873-2429
• DOI: 10.1016/0375-9601(94)90971-7

Current diffusion was studied during edge ohmic heating (EOH) experiments in the HT-6M tokamak. The EOH power system makes the plasma current linearly ramp up from an initial steady state ( I p=55kA) to a second steady state ( I p=60kA) at a fast ramp rate of 12 MA/s. A stable discharge of an improved confinement was observed experimentally in the HT-6M tokamak after the plasma current was ramped to rise rapidly to a second steady state. The plasma current is ramped up much faster than both the classical skin time and neoclassical skin time. Fast current ramp up increases the anomalous current diffusion. The measured values of β P +l i 2 and the soft X-ray sawtooth inversion radius imply the anomalous current penetration. The mechanism of anomalous penetration and improved confinement is discussed.