Validation of the plasma-wall self-organization model for density limit in ECRH-assisted start-up of Ohmic discharges on J-TEXT

• Published in: Nuclear fusion Vol. 63; no. 9; pp. 96009 - 96018
• Main Authors: Liu, Jiaxing, Zhu, Ping, Escande, Dominique Franck, Zhang, Junli, Xia, Donghui, Wang, Yuhan, Wang, Jiaming, Yang, Qinghu, Fang, Jiangang, Zhang, Xiaoqing, Gao, Li, Cheng, Zhifeng, Chen, Zhipeng, Yang, Zhoujun, Chen, Zhongyong, Ding, Yonghua, Pan, Yuan
• Format: Journal Article
• Language: English
• Published: IAEA IOP Publishing 01.09.2023
• Subjects: density limit; ECRH; J-TEXT; Physics; Plasma Physics; plasma wall interaction; radiation; Density limit; ECRH; radiation; plasma wall interaction; J-TEXT
• ISSN: 0029-5515; 1741-4326
• DOI: 10.1088/1741-4326/ace91c

Abstract A recently developed plasma-wall self-organization model (Escande et al 2022 Nucl. Fusion 62 026001) predicts a significantly enhanced density limit, which may be attainable in tokamaks with ECRH-assisted Ohmic start-up and sufficiently high initial neutral density. Experiments have been conducted on J-TEXT to validate such a density limit scenario based on this model. Experimental results demonstrate that increasing the pre-filled gas pressure or ECRH power during the start-up phase can help effectively enhance plasma purity and raise the density limit at the flat-top phase. The experimental data shows that density limit increases by a ratio 0.76 / 0.6 ≈ 1.27 for a decrease by a factor 0.13 / 0.33 ≈ 0.4 in C III radiation.