Upgrade of vacuum ultraviolet spectroscopy system on J-TEXT tokamak

The vacuum ultraviolet (VUV) spectroscopy system on the Joint Texas Experimental Tokamak has been upgraded to achieve fast acquisition for the study of impurity transport in transient modulated experiments. In this upgrade, the previous high-energy charge-coupled device detector was replaced by a microchannel plate with a CsI-coated photocathode and P43 phosphor to transform the VUV light to visible light, which is then acquired by a high-speed electron-multiplying charge-coupled device. Two-stage focusing was achieved using a reference slit plate illuminated successively by a green light source and the Lyman series hydrogen spectral lines from the vacuum-conditioning plasma. The spatial resolution was evaluated as similar to 4 mm based on the level of image blurring from the alignment plate. A response time of similar to 2 ms was obtained with the ten-vertical-track setup. (C) 2021 Author(s).

Automated summary

The vacuum ultraviolet (VUV) spectroscopy system on the Joint Texas Experimental Tokamak has been upgraded to improve data acquisition speed and spatial resolution for the study of impurity transport in transient modulated experiments.