SUNIST Program and Improvement of Operation on SUNIST Spherical Tokamak

Abstract

Spherical tokamak program in China was started up from 1999. The Sino United Spherical tokamak (SUNIST) has been assembled in November 2002. Test discharge of SUNIST completed at the end of 2002. We got the plasma with about 50 kA of current in test discharge without flattop on plasma current. After modification of the power supply of vertical field in 2003, we obtained fine equilibrium plasma current on SUNIST with about 2 ms flattop. The SUNIST laboratory has been founded in 2004, consisted of Department of Engineering Physics, Tsinghus University (DEPTS.) and Institute of Physics, Chinese Academy of Sciences (IOPCAS). A series of experiments has been taken on edge plasma parameters, fluctuation and turbulence before and after power supply modification. At the end of 2003, we tried to deposit siliconized film on vacuum vessel. After siliconization, plasma current flattop could extend to the regime where the signal of loop flux had fell down to zero.