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| Hauptseite > Publikationsdatenbank > Assessment of plasma edge transport in Neon seeded plasmas in disconnected double null configuration in EAST with SOLPS-ITER |
| Hauptseite > Publikationsdatenbank > Assessment of plasma edge transport in Neon seeded plasmas in disconnected double null configuration in EAST with SOLPS-ITER |
| Abstract | FZJ-2021-01566 |
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2021
Abstract: Assessment of plasma edge transport in Neon seeded plasmas in disconnected double null configuration in EAST with SOLPS-ITERD. Boeyaert1,3, S. Wiesen1, M. Wischmeier2, W. Dekeyser3, S. Carli3, L. Wang4, F. Ding4, K. Li4, Y. Liang1,4, M. Baelmans3, and the EAST-teama1Forschungszentrum Jülich GmbH, Institut für Energie- und Klimaforschung – Plasmaphysik, D-52425 Jülich, Germany2Max-Planck-Institut für Plasmaphysik, Boltzmannstraße 2, 85748 Garching, Germany3KU Leuven, Department of Mechanical Engineering, Celestijnenlaan 300, 3001 Leuven, Belgium4Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, People’s Republic of China aSee appendix of Wan B.N. et al 2019 Nucl. Fusion 59 112003 d.boeyaert@fz-juelich.dePower and particle exhaust is essential for future nuclear fusion reactors [1]. This exhaust is determined by the perpendicular/radial transport inside the Scrape-Off Layer (SOL) which include drifts and currents, neutral kinetics, radiation and (radial) anomalous transport. Under high power conditions in future all-metal fusion devices like ITER or DEMO, extrinsic impurity seeding is required to induce divertor detachment through impurity radiation. Due to the lack of surface chemistry, noble gases like neon (Ne) are key candidates as main radiator. Besides JET [2], EAST is the only tokamak that currently handles stable H-modes with Neseeding in a metallic environment as the main (upper) divertor is made out of tungsten. This device has the flexibility to do both upper single null (USN) and double null (DN) configurations with the latter showing good prospects to handle exhaust with good core confinement [3]. USN discharges in EAST are setup as disconnected DN (DDN) with a large separation between separatrices upstream (drsep) of about ~ 2cm. This causes a remaining influx of eroded C impurities from the lower (non-active) divertor. This contribution analyzes Ne seeded and unseeded DDN deuterium discharges at EAST with decreasing drsep, both with experimental data from EAST and SOLPS-ITER simulations [4] . Ne seeded discharges in H-mode from the 2019 EAST campaign are studied (heating power Pheat = 2.5 MW, plasma current Ip = 0.4 MA and toroidal field Bt = 2.4 T). For the first time, a DDN configuration with divertor Te-feedback for the Ne puff strength was attempted to achieve steady divertor conditions. A radiative fraction Prad/Pheat of up to 30% was achieved with Ne seeding while 10% is achieved without. Ne in all cases was injected from the upper (active) outer target and a significant target temperature drop was identified from the Langmuir probes. The effect of a DDN configuration however is limited as the upstream power scrape-off width (~0.5cm [5]) is significantly smaller compared to the achieved separation between the separatrices (drsep ~ 1.5 cm). SOLPS-ITER simulations are being carried out to interpret the experimental results to understand the influence of the different transport types in the SOL for a dissipative DDN divertor geometry with and without Ne seeding and C erosion. The model includes for the first time for EAST fluid drifts and edge currents in the SOL. SOLPS-ITER will be used to predict the performance of a Ne seeded EAST DN divertor (with drsep = 0) being closest to one of theconsidered DEMO divertor geometries. [1] M. Wischmeier, et al., J. Nucl. Mater. 22-29 (2015) 463; [2] S. Glöggler, et al., Nucl. Fusion. 126031 (2019) 59 ; [3] H. Meyer, et al., Nucl. Fusion. 64-72 (2006) 46; [4] S. Wiesen et al., J. Nucl. Mat. 480-484 (2015) 463 ; [5] T. Eich, et al., Nucl. Fusion 093031 (2013) 53
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