Investigation of argon transport by X-Ray imaging crystal spectrometer on J-TEXT

Abstract A tangential X-ray imaging crystal spectrometer (XICS) has been upgraded in the J-TEXT tokamak. The XICS system has been used to measure ion and electron temperature, plasma rotation velocities, selected impurity densities, and can be used for impurity transport. The XICS on J-TEXT was designed to receive Ar XVII emissions from the -0.5a to +0.5a region with a spatial resolution of 1.8 cm in the vertical direction, a is the minor radius. The temporal evolution of argon impurity density profiles after an argon gas puffed were observed with a time resolution of up to 2 ms. The behaviour of argon was investigated under different discharge conditions. The experimental results show that, as the density increased, the impurity confinement time obviously increased. Simulation results obtained by STRAHL showed that the convection velocity changed from negative to positive as the electron density increased. This indicated that impurities moved more favourably toward the plasma boundary.