Numerical investigation of a new ICRF heating scenario in D-T plasma on CFETR

• Published in: Physica scripta Vol. 96; no. 2; pp. 25603 - 25613
• Main Authors: Song, Chengyi, Yin, Lan, Yang, Cheng, Gong, Xueyu, Zheng, Pingwei, Huang, Qianhong, Xia, Yanbo, Chen, You
• Format: Journal Article
• Language: English
• Published: IOP Publishing 01.02.2021
• Subjects: bulk ion heating; CFETR; ICRF
• ISSN: 0031-8949; 1402-4896
• DOI: 10.1088/1402-4896/abd2e2

Abstract For a fusion device, plasma pre-heating is required before the self-sustaining burning-state reactions of deuterium (D) and tritium (T) commence. Plasma heating with waves in the ion-cyclotron range of frequencies (ICRF) is effective in tokamaks. A new three-ion ICRF heating scheme for plasmas in the Chinese Fusion Engineering Test Reactor (CFETR) that require an increase in the bulk ion temperature via heating the lithium impurities in the D–T plasmas, was studied numerically. Our simulations show that the radio-frequency wave power is strongly absorbed by very few 7 Li ions with concentrations of 0.01%–0.2% in a suitable mixture of D–T plasmas, the enhanced minority ion heating is related to that the 7 Li fundamental resonance layer is very close to the two mode conversion layers. In adjusting the mixtures over a wide range of composition, an oscillatory behaviour in the 7 Li absorption efficiency arises because of interference. Moreover, from estimates of the 7 Li ion tail energy, most of the tail energy of the minority ions is found to be transferred to background ions via collisions. Compared with the routine ( 3 He)-D–T scheme, the ICRF power is absorbed more effectively by the 7 Li ions in the ( 7 Li)-D–T heating scenario, and after the Fokker–Planck equations were solved, a large fraction of bulk ion heating was evident in the ( 7 Li)-D–T heating scenario. The new three-ion scenario may therefore be an attractive proposition for bulk ion heating during the activated phase of the reactor.