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

Abstract In the HT-7 superconducting tokamak, long-pulse discharge was generated by synergy of high power LHCD (300–600 kW, 2.45 GHz) and high power IBW (200–350 kW, 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 (Ip = 120–180 kA, BT = 1.5–2 T, Te(0) = 2–4 keV, and 〈ne〉 = 1–2.5 × 1019 m−3) was achieved with the operational pulse length of 1–10 s. For lower performance operation, more than 60 s of long-pulse plasma was obtained by the LHCD in 2003 on the HT-7 tokamak.