Bolometer measurements of the radiated power and estimates of the effective ion charge Zeff on the Keda Torus eXperiment

• Published in: Fusion engineering and design 2020-03, Vol.152, p.1, Article 111416
• Main Authors: Zhu, Junfeng, Lan, Tao, Deng, Tijian, Wu, Jie, Xu, Hangqi, Chen, Chen, Zhang, Sen, Wu, Jiaren, Zu, Yiming, Li, Hong, Xie, Jinlin, Liu, Ahdi, Mao, Wenzhe, Zhou, Chu, Liu, Zixi, Wu, Zhengwei, Wang, Hai, Wen, Xiaohui, Zhou, Haiyang, Wei, Zian, Xiao, Chijin, Ding, Weixing, Zhuang, Ge, Liu, Wandong
• Format: Article
• Language: English
• Subjects: AXUV bolometer; Bandwidths; Bolometers; Frequency response; H alpha line; Ion charge; KTX; Mathematical analysis; Radiation power loss; Spatial resolution; Toruses; Zeff
• ISSN: 0920-3796; 1873-7196
• DOI: 10.1016/j.fusengdes.2019.111416

•Together with the Hα-emission data, a new method has been used to determine the effective ion charge Zeff using bolometer measurements.•For convenience in repairing the detectors if they develop problems, the diagnostic systems are connected with a fully sealed magnetic transmission.•Black aluminum foil, an ideal material for eliminating unwanted light, is attached onto the internal surfaces of the diagnostic systems. We have measured the power radiated by the plasma in the Keda Torus eXperiment (KTX) using a 20-channel AXUV bolometer. The bolometer has a frequency response bandwidth of 40 kHz, spatial resolution better than 40 mm, and overlap between adjacent channels of about 20%. For an ultra-low q discharge, the radiated power obtained from the bolometer measurements is about 8.0% of the ohmic heating input power. In addition, together with the Hα-emission data, we have used the bolometer data to calculate the effective ion charge Zeff profile, which proves to agree well with a plasma-resistivity calculation and which is hollow in the central region of a poloidal cross-section of the KTX.