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| Home > Publications database > Experimental studies of H-mode divertor detachment with deuterium gas injection in KSTAR plasmas |
| Abstract | FZJ-2021-01570 |
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2021
Abstract: Experimental studies of H-mode divertor detachmentwith D2 injection in KSTARJ. H. Hwanga, J.-S. Parkb, R. Pittsb, H. H. Leec, J.-W. Juhnc, J. Jangc,J. G. Bakc,S. Wiesend, M. Bernerte,S.-H. Hongc, and W. Choea a KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Koreab ITEROrganization, Route de Vinon-sur-Verdon, CS 90 046, 13067 St. Paul Lez Durance Cedex, FrancecNational Fusion Research Institute, 169-148 Gwahak-ro, Yuseong-gu,Daejeon 34133, KoreadForschungszentrum Jülich GmbH, Institut für Energie-und Klimaforschung -Plasmaphysik, D-52425 Jülich, GermanyeMax Planck Institute for Plasma Physics, Boltzmannstraße 2, 85748 Garching, Germanyhoo1021@kaist.ac.kr; wchoe@kaist.ac.krSince H-mode has beenregarded as a promising operating scenario for future tokamaks, it is important to get a good understanding of divertor detachment in H-mode plasmas.So far the extensive detachment studies in KSTAR focused on L-mode plasmas [1]. Therefore, H-mode detachmentstudies with pure deuterium fuelled discharges with no impurity gas seedingcan bethe baseline starting point for further complex studies of detachment under impurity injections or ELMcontrolled/suppressed 3D field configurations in KSTAR. In this study, the first signs of H-mode divertor detachmentby deuterium gas injectionin KSTARwere obtained in electron density ramp discharges.The discharges in this study had Ip=0.7 MA and Bt= 1.8 T with ∇B-drift directed downward into the lower divertor. The total NBI heating power was 2.9-3.1 MW. In the experiment, the outer target showed a partially detached regime and the inter-ELM peak particle flux was reduced significantly by a factor of 5 to below 2.0x1022m-2s-1. At the inner target, particle flux roll-over occurred although there was not significant reduction of the inter-ELM peak particle flux.The line-integrated density rose up to about 6.0x1019m-3(fGW≈0.8) and further density increase for accessing pronounced detachment was failed by arriving at the H-mode density limit [2]. Theanomalous in/out detachment asymmetry in which the outer target detaches at the lower core density than the inner target has been observedin KSTAR L-mode plasmas [1]and it wasshown that the asymmetry was reproduced in KSTAR H-mode plasmas.This work will act as reference for more complex H-mode detachment studies to be pursued on KSTARand contribute to better understanding of physics behind divertor detachment.Experimental resultscould give several important constraints to theSOLPS-ITERmodelling so that the benchmarking and predictive research regarding KSTAR boundary plasmas will be possible.[1] J.-S. Park, et al., Nucl. Fusion 58 126033 (2018)[2] M. Bernert, et al., Plasma Phys. Control. Fusion 57 014038 (2015)
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