Long-pulse discharges by synergy of LHW and IBW heating in the HT-7 tokamak

In the HT-7 superconducting tokamak, long-pulse discharge was generated by synergy of high power LHCD (300-600kW, 2.45GHz) and high power IBW (200-350kW, 27 MHz) heating. Recently, a new set of actively cooled toroidal double-ring graphite limiters at bottom and top of the vacuum vessel has been developed for long-pulse operation in the HT-7. Based on the understanding of plasma surface interactions, nearly full non-inductive current driven plasma (I-p = 120-180kA, B-T = 1.5-2T, T-e(0) = 2-4keV, and (n(e)) = 1-2.5 x 10(19) m(-3)) was achieved with the operational pulse length of 1-10s. For lower performance operation, more than 60s of long-pulse plasma was obtained by the LHCD in 2003 on the HT-7 tokamak. (c) 2004 Elsevier B.V. All rights reserved.