The gas puffing performance plays a key role in repeatable discharges in the Sino- UNited Spherical Tokamak （SUNIST） experiments. In this paper, temporal evolution of the gas pressure in the vacuum vessel and the de...The gas puffing performance plays a key role in repeatable discharges in the Sino- UNited Spherical Tokamak （SUNIST） experiments. In this paper, temporal evolution of the gas pressure in the vacuum vessel and the dependence of the repeatability of plasma discharges on different timing arrangements between the gas puffing pulse and the Ohmic field have been experimentally investigated. The results show that, after a fast rising phase, the gas pressure becomes quasi-stationary. In the regime of the discharges being started up when the gas pressure has already reached the quasi-stationary state for about 37 ms, an improved repeatability of the plasma discharges is achieved.展开更多
A magnetic measurement system consisting of magnetic probes and flux loops for spherical tokamak SUNIST, is uniquely designed due to the strongly shaped plasma cross section and the narrow space near the central solen...A magnetic measurement system consisting of magnetic probes and flux loops for spherical tokamak SUNIST, is uniquely designed due to the strongly shaped plasma cross section and the narrow space near the central solenoid. Plasma equilibrium reconstruction with the current filament method is performed to determine the number and positions of the magnetic probes and flux loops, as well as their design precision required.展开更多
Internal reconnection event （IRE）, which is characterized by a perturbation in plasma current Ip, loop voltage Vloop, Hα radiation and magnetic perturbation dBp, was observed in the SUNIST experiment. It is found t...Internal reconnection event （IRE）, which is characterized by a perturbation in plasma current Ip, loop voltage Vloop, Hα radiation and magnetic perturbation dBp, was observed in the SUNIST experiment. It is found that, the fluctuation before IREs is characterized by a structure of m= 2/n = 1, then changes to m = 4/n = 1 during the IREs; and, after IREs, the mode number changes to m = 3/n = 1. An analysis in the evolution of equilibrium parameters during IREs shows that a positive spike appears in the evolution of the plasma＇s elongation and a negative spike in the poloidal beta of plasma. A collapse in the pressure profile, corresponding to the occurrence of IREs, is also found.展开更多
基金supported by National Natural Science Foundation of China(Nos.10990214,11175103,11261140327 and 11075092)Ministry of Science and Technology(MOST)of China(Nos.2013GB112001 and 2010GB107002)Tsinghua University Initiative Scientific Research Program
文摘The gas puffing performance plays a key role in repeatable discharges in the Sino- UNited Spherical Tokamak （SUNIST） experiments. In this paper, temporal evolution of the gas pressure in the vacuum vessel and the dependence of the repeatability of plasma discharges on different timing arrangements between the gas puffing pulse and the Ohmic field have been experimentally investigated. The results show that, after a fast rising phase, the gas pressure becomes quasi-stationary. In the regime of the discharges being started up when the gas pressure has already reached the quasi-stationary state for about 37 ms, an improved repeatability of the plasma discharges is achieved.
基金National Science Foundation of China(No.10535020)the Foundation for the Authors of National Excellent Doctoral Dissertation of China(No.200456)
文摘A magnetic measurement system consisting of magnetic probes and flux loops for spherical tokamak SUNIST, is uniquely designed due to the strongly shaped plasma cross section and the narrow space near the central solenoid. Plasma equilibrium reconstruction with the current filament method is performed to determine the number and positions of the magnetic probes and flux loops, as well as their design precision required.
基金supported by National Natural Science Foundation of China(Nos.10405014,10990214)MOST of China(Nos.2009GB105002 and 2008GB717804)in part by the JSPS-CAS Core-University program in the field of 'Plasma and Nuclear Fusion'
文摘Internal reconnection event （IRE）, which is characterized by a perturbation in plasma current Ip, loop voltage Vloop, Hα radiation and magnetic perturbation dBp, was observed in the SUNIST experiment. It is found that, the fluctuation before IREs is characterized by a structure of m= 2/n = 1, then changes to m = 4/n = 1 during the IREs; and, after IREs, the mode number changes to m = 3/n = 1. An analysis in the evolution of equilibrium parameters during IREs shows that a positive spike appears in the evolution of the plasma＇s elongation and a negative spike in the poloidal beta of plasma. A collapse in the pressure profile, corresponding to the occurrence of IREs, is also found.
