Multi-device Studies of Pedestal Physics and Confinement in the I-mode Regime

Dataset · Thu Apr 01 00:00:00 EDT 2021

DOI:https://doi.org/10.7910/DVN/JDPLN1· OSTI ID:1882383

Hubbard, A. E.; Osborne, T.; Ryter, F.; Gao, X.; Ko, J.; Orte, L. Barrera; Churchill, R. M.; Cziegler, I.; Fenstermacher, M.; Fischer, R.; Gerhardt, S.; Groebner, R.; Gohil, P.; Happel, T.; Hughes, J. W.; Liu, Z. X.; Loarte, A.; Maingi, R.; Marinoni, A.; Marmar, E. S. ; McDermott, R. M.; McKee, G.; Rhodes, T.; Rice, J. E.; Schmitz, L.; Theiler, C.; Viezzer, E.; Walk, J. R.; White, A.; Whyte, D.; Wolfe, S.; Wolfrum, E.; Yan, Z.; Zhang, T.

This paper describes joint ITPA studies of the I-mode regime, which features an edge thermal barrier but with L-mode-like particle and impurity transport, and without ELMs. The regime has been demonstrated on Alcator C-Mod, ASDEX Upgrade and DIII-D tokamaks, over a wide range of device parameters and pedestal conditions, including low collisionality. Access to I-mode is independent of heating method (neutral beam injection, ICRH and/or ECRH). Normalized energy confinement H98y,2 ≥ 1 has been achieved for a range of 3≤q95≤4.9 and scales favourably with power. Changes in turbulence in the pedestal region accompany the transition from L-mode to I-mode. The L-I threshold increases with plasma density and current, and with device size, but weakly with BT. The upper limit of power for I-modes increases with toroidal field, and is largest on Alcator C-Mod at B > 5 T. Issues for extrapolation to ITER and other future fusion devices are discussed.

• Research Organization: Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Plasma Science and Fusion Center; General Atomics, San Diego, CA (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Univ. of Wisconsin, Madison, WI (United States); Univ. of California, Los Angeles, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Fusion Energy Sciences (FES); USDOE National Nuclear Security Administration (NNSA)
• DOE Contract Number: FC02-99ER54512; FC02-04ER54698; FG02-94ER54235; AC52-07NA27344; AC02-09CH11466; FG02-89ER53296; FG02-08ER54999; FG02-08ER54984
• OSTI ID: 1882383
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY