Progress of recent experimental research on the J-TEXT tokamak

Abstract

The progress of experimental research over the last two years on the J-TEXT tokamak is reviewed and reported in this paper, including: investigations of resonant magnetic perturbations (RMPs) on the J-TEXT operation region show that moderate amplitude of applied RMPs either increases the density limit from less than 0.7nG to 0.85nG (nG is the Greenwald density, ) or lowers edge safety factor qa from 2.15 to nearly 2.0; observations of influence of RMPs with a large m/n = 3/1 dominant component (where m and n are the toroidal and poloidal mode numbers respectively) on electron density indicate electron density first increases (decreases) inside (around/outside) of the 3/1 rational surface, and it is increased globally later together with enhanced edge recycling; investigations of the effect of RMPs on the behavior of runaway electrons/current show that application of RMPs with m/n = 2/1 dominant component during disruptions can reduce runaway production. Furthermore, its application before the disruption can reduce both the amplitude and the length of runaway current; experimental results in the high-density disruption plasmas confirm that local current shrinkage during a multifaceted asymmetric radiation from the edge can directly terminate the discharge; measurements by a multi-channel Doppler reflectometer show that the quasi-coherent modes in the electron diamagnetic direction occur in the J-TEXT ohmic confinement regime in a large plasma region (r/a ~ 0.3–0.8) with frequency of 30–140 kHz.

Beta-induced Alfvén eigenmodes destabilized by resonant magnetic perturbations in the J-TEXT tokamak

“…J-TEXT is a circular tokamak with major radius ~1.05 m and minor radius ~0. 245-0.3 m controlled by a removable limiter [39]. The in-vessel RMPs system is equipped [40], which consists of 24 saddle coils located at 8 toroidal locations and 3 poloidal locations (top, middle at low field side and bottom) showed in figure 1.…”

The impact of an m/n = 2/1 locked mode on the disruption process during a massive gas injection shutdown on J-TEXT

“…J-TEXT is a circular, medium-sized limiter tokamak with a major radius R 0 = 105 cm and minor radius a, which can be modified in the range of 25 to 29 cm [29]. The maximum toroidal magnetic field is B T = 2.5 T, the maximum plasma current is I P = 240 kA, the center line-averaged electron density is in the range of n e = 1 to 5 ×10 19 m −3 and the electron temperature T e is about 0.8 keV.…”

Plans for the electron cyclotron heating system on J-TEXT

“…For the J-TEXT tokamak, the maximum toroidal magnetic field is 2.4 T at present [9]. Considering the needs of physics experiment and values, the 105 GHz/500 kW/1 s gyrotron, which is manufactured by GYCOM, has been chosen for J-TEXT tokamak.…”