학술논문
Progress in reducing ICRF-specific impurity release in ASDEX upgrade and JET
Document Type
article
Author
V. Bobkov; D. Aguiam; M. Baruzzo; D. Borodin; I. Borodkina; S. Brezinsek; I. Coffey; L. Colas; A. Czarnecka; E. Delabie; P. Dumortier; F. Durodie; R. Dux; H. Faugel; H. Fünfgelder; C. Giroud; M. Goniche; J. Hobirk; A. Herrmann; J. Jacquot; Ph. Jacquet; A. Kallenbach; A. Krivska; C.C. Klepper; E. Lerche; S. Menmuir; D. Milanesio; R. Maggiora; I. Monakhov; F. Nave; R. Neu; J.-M. Noterdaeme; R. Ochoukov; Th. Pütterich; M. Reinke; A. Tuccilo; O. Tudisco; D. Van Eester; Y. Wang; Q. Yang; W. Zhang
Source
Nuclear Materials and Energy, Vol 12, Iss , Pp 1194-1198 (2017)
Subject
Language
English
ISSN
2352-1791
Abstract
Use of new 3-strap ICRF antennas with all-tungsten (W) limiters in ASDEX Upgrade results in a reduction of the W sources at the antenna limiters and of the W content in the confined plasma by at least a factor of 2 compared to the W-limiter 2-strap antennas used in the past. The reduction is observed with a broad range of plasma shapes. In multiple locations of antenna frame, the limiter W source has a minimum when RF image currents are decreased by cancellation of the RF current contributions of the central and the outer straps. In JET with ITER-like wall, ITER-like antenna produces about 20% less of main chamber radiation and of W content compared to the old A2 antennas. However the effect of the A2 antennas on W content is scattered depending on which antennas are powered. Experiments in JET with trace nitrogen (N2) injection show that a presence of active ICRF antenna close to the midplane injection valve has little effect on the core N content, both in dipole and in -90° phasing. This indicates that the effect of ICRF on impurity transport across the scape-off-layer is small in JET compared to the dominant effect on impurity sources leading to increased impurity levels during ICRF operation. Keywords: ICRF, RF sheath, Three-strap, 3-strap, ASDEX Upgrade, JET, ILW, A2 antenna, ILA, Sputtering