Design of the poloidal field system and plasma equilibrium of HT-7U tokamak

HT-7U superconducting tokamak is an advanced steady-state plasma physics experimental device will be built in Hefei at the Chinese Academy of Sciences, Institute of Plasma Physics (CASIPP). The HT-7U device is a full superconducting Tokamak which means that the toroidal field (TF) coils system and poloidal field coils (PF) systems are used with superconducting conductor. There are fourteen superconducting PF coils, including central selenoid, located symmetrically about the equator plane. The selenoid is supported by the case of TF coils. The NbTi cable-in-conduit conduct (CICC) cooled by supercritical helium at 4.5 K is chosen as superconductor for all of the PF and TF coils. The plasma current is ∼1 MA and the duration of the plasma is ∼10 s for ohmic heating discharge. The preliminary engineering design of PF and the results of the calculating for plasma equilibrium will be reported in this paper. The maximum capacity of the magnetic flux for PF is ∼10 Web and the stray field in plasma initiate region is quite low. The peak magnetic field in PF coils is ∼4.5 T. Three type shapes of plasma can be chosen during the operating which are shown in the result of our calculations