May 8-10

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Author: Matthew T. Beidler
Requested Type: Poster
Submitted: 2023-04-03 07:37:38

Co-authors: E.M. Hollmann, Y.Q. Liu, R.A. Pitts, D.L. Rudakov, I. Bykov, C.J. Lasnier, J. Ren

Contact Info:
Oak Ridge National Laboratory
PO Box 2008
Oak Ridge, TN   37831
USA

Abstract Text:
Understanding the consequences of runaway electron (RE) beam impacts on plasma-facing components is necessary for gauging the efficacy of a given mitigation scenario. Recent modeling has focused on developing models for the volumetric energy deposition and melt damage [1] and impact RE distributions [2] during final RE loss events. These models are presently used to help explain DIII-D experiments where a RE beam is purposefully made to impact a graphite dome protruding 1 cm from the divertor floor tiles and inserted using the Divertor Material Evaluation System (DiMES) [3]. This work details modeling efforts with the KORC code to track guiding center RE orbits impacting the graphite dome during the final loss event. We use a magnetic reconstruction near the time of RE beam impact and perform a MARS-F calculation for the linear 3D perturbation magnetic field, finding a dominant internal-kink instability with a minor external-kink component. Simulations show that a small fraction of the modeled REs strike the analytically modeled graphite dome. We see a qualitative agreement with experimental results, where modeled RE deposition is consistent with the topology of the material missing on the sample. A parametric scan over the initial energy and pitch of the modeled RE beam shows that the deposition fraction increases with both energy and pitch. The modeled RE distribution deposited on the dome will be used in future modeling with volumetric energy deposition and melt damage codes to validate these models for predictive studies. [1] Chen et al., AAPPS-DPP contribution MF2-I14 (2021) [2] Beidler et al., in preparation (2023) [3] Wong et al., J. Nucl. Mat. 258-263, 433 (1998) This work is supported by the US DOE under contracts DE-AC05-00OR22725, DE-FC02-04ER54698, and DE-AC02-05CH11231 and by the ITER Organization (TA C18TD38FU). The views and opinions expressed herein do not necessarily reflect those of the European Commission or the ITER Organization.

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