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DOE OSTI · 2564472

TorbeamNN: machine learning-based steering of ECH mirrors on KSTAR

Rothstein, Andrew [Princeton Univ., NJ (United States)] (ORCID:0000000321830997)·Kim, Minseok [Princeton Univ., NJ (United States)] (ORCID:0009000216646618)·Woo, Minho [Korea Institute of Energy Research (KIER), Daejeon (Korea, Republic of)] (ORCID:0000000338183888)·Cha, Minsoo [Seoul National Univ. (Korea, Republic of)] (ORCID:0009000491250984)·Byun, Cheolsik [Princeton Univ., NJ (United States)] (ORCID:0009000708691116)·Kim, Sangkyeun [Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)] (ORCID:0000000207018962)·Erickson, Keith [Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)] (ORCID:0000000312168719)·Lee, Youngho [Korea Institute of Energy Research (KIER), Daejeon (Korea, Republic of)] (ORCID:0000000252854599)·Josephy-Zack, Josh [Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)] (ORCID:0000000270966471)·Butt, Jalal [Princeton Univ., NJ (United States)] (ORCID:0000000233226060)·Shousha, Ricardo [Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)] (ORCID:0000000314988980)·Joung, Mi [Korea Institute of Energy Research (KIER), Daejeon (Korea, Republic of)] (ORCID:0009000898647334)·Juhn, June-Woo [Korea Institute of Energy Research (KIER), Daejeon (Korea, Republic of)] (ORCID:0000000294354349)·Lee, Kyu-Dong [Korea Institute of Energy Research (KIER), Daejeon (Korea, Republic of)] (ORCID:0009000704805358)·Kolemen, Egemen [Princeton Univ., NJ (United States); Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)] (ORCID:0000000342123247)
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Abstract

We have developed TorbeamNN: a machine learning surrogate model for the TORBEAM ray tracing code to predict electron cyclotron heating (ECH) and current drive locations in tokamak plasmas. TorbeamNN provides more than a 100 times speed-up compared to the highly optimized and simplified real-time implementation of TORBEAM without any reduction in accuracy compared to the offline, full fidelity TORBEAM code. The model was trained using KSTAR ECH mirror geometries and works for both O-mode and X-mode absorption. The TorbeamNN predictions have been validated both offline and real-time in experiment. TorbeamNN has been utilized to track an ECH absorption vertical position target in dynamic KSTAR plasmas as well as under varying toroidal mirror angles and with a minimal average tracking error of 0.5 cm.

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70 PLASMA PHYSICS AND FUSION TECHNOLOGYTokamakelectron cyclotron heatingmachine learning surrogatenuclear fusion

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Rothstein, Andrew [Princeton Univ., NJ (United States)] (ORCID:0000000321830997), Kim, Minseok [Princeton Univ., NJ (United States)] (ORCID:0009000216646618), Woo, Minho [Korea Institute of Energy Research (KIER), Daejeon (Korea, Republic of)] (ORCID:0000000338183888), Cha, Minsoo [Seoul National Univ. (Korea, Republic of)] (ORCID:0009000491250984), Byun, Cheolsik [Princeton Univ., NJ (United States)] (ORCID:0009000708691116), Kim, Sangkyeun [Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)] (ORCID:0000000207018962), Erickson, Keith [Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)] (ORCID:0000000312168719), Lee, Youngho [Korea Institute of Energy Research (KIER), Daejeon (Korea, Republic of)] (ORCID:0000000252854599), Josephy-Zack, Josh [Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)] (ORCID:0000000270966471), Butt, Jalal [Princeton Univ., NJ (United States)] (ORCID:0000000233226060), Shousha, Ricardo [Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)] (ORCID:0000000314988980), Joung, Mi [Korea Institute of Energy Research (KIER), Daejeon (Korea, Republic of)] (ORCID:0009000898647334), Juhn, June-Woo [Korea Institute of Energy Research (KIER), Daejeon (Korea, Republic of)] (ORCID:0000000294354349), Lee, Kyu-Dong [Korea Institute of Energy Research (KIER), Daejeon (Korea, Republic of)] (ORCID:0009000704805358), Kolemen, Egemen [Princeton Univ., NJ (United States); Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)] (ORCID:0000000342123247). 2025-05-06. TorbeamNN: machine learning-based steering of ECH mirrors on KSTAR. https://doi.org/10.1088/1361-6587%2Fadd08b

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