Abstract Details
Abstracts
Author: Andreas Kleiner
Requested Type: Poster
Submitted: 2023-03-31 13:56:43
Co-authors: N.M.Ferraro, G.P.Canal, B.Lyons, R.Maingi, J.T.McClenaghan, J.Menard, S.Munaretto, J.Parisi, M.Reinke, R.Sweeney
Contact Info:
Princeton Plasma Physics Laboratory
100 Stellarator Road
Princeton, New Jersey 08540
United States
Abstract Text:
Edge-localized modes (ELMs) and disruptions are two transient phenomena that can cause serious damage to the vessel in reactor-scale tokamaks and thus need to be controlled or mitigated. We present extended-magnetohydrodynamic (MHD) simulations with the goal of accurately predicting ELM stability thresholds in spherical tokamaks (STs) and to inform the massive gas injection (MGI) layout for disruption mitigation in SPARC.
ELMs are typically associated with macroscopic peeling-ballooning (PB) modes in the edge pedestal, which arise due to strong pressure and current density gradients. In large aspect ratio devices these ideal-MHD modes are well understood. However, a long-standing problem has been the reliable modeling of such stability boundaries and prediction of pedestal parameters in some ST scenarios, particularly in NSTX. In simulations with the extended-MHD code M3D-C1, it was found that plasma resistivity can significantly alter macroscopic edge-stability in ELMing H-mode discharges in NSTX. Nonlinearly saturated edge modes that exhibit similarities to edge-harmonic oscillations are found in NSTX enhanced-pedestal H-mode. The analysis of PB stability is extended to STAR, a preliminary ST-based power plant design. We show how these extended-MHD stability thresholds are incorporated into a higher-fidelity model to predict the pedestal structure in a wider range of scenarios.
We also present extended-MHD simulations of disruption mitigation in SPARC using MGI. Fully three-dimensional M3D-C1 simulations are carried out for various injector configurations with the primary goal of determining the effect of different MGI parameters on heat loads and vessel forces. The simulations include a model for impurity ionization, recombination, advection and radiation, as well as spatially resolved conducting structures in the wall. Two-injector simulations indicate good mitigation, but with large peaking factors. Simulations with up to six injectors are ongoing.
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