Beam halo losses reduction with simulation constrained Bayesian Optimization

WEIBC01
Oct 22, 2025, 11:00 AM
30m
Room C (Conference Center)

Room C

Conference Center

Invited Oral Presentation WGE: Beam Instrumentation, beam Interaction and AI technology WEIBC WGE invited oral

Speaker

Jibong Hyun (National Institutes for Quantum Science and Technology)

Description

The Linear IFMIF Prototype Accelerator (LIPAc) aims to demonstrate CW acceleration of a 125 mA deuteron beam up to 9 MeV using an RFQ and SRF linac. Before SRF linac installation, the beam commissioning was conducted with a 5 MeV deuteron beam. Attempts to increase the duty cycle revealed a significant pressure rise detected by sensors, presumably caused by beam halo, which had previously limited operation to ~3%. To address this limitation, a Bayesian optimization was applied to the beam optics (four quads and steerers), aiming to minimize halo-induced losses by monitoring vacuum pressure while constraining core losses. The algorithm successfully decreased the sector vacuum pressure by about 67%. Simulations also confirmed that halo formation from space-charge forces was mitigated by relaxing beam focusing in specific regions consistent with theoretical predictions of beam physics. This enabled stable operation up to 8.7% duty cycle. These results demonstrate that machine learning can effectively support optics tuning even in high-current accelerators. This talk presents beam optics before and after the optimization process and the resulting improvements in halo minimization.

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Author

Jibong Hyun (National Institutes for Quantum Science and Technology)

Co-authors

Andrea De Franco (National Institutes for Quantum Science and Technology) Yann Carin (Fusion for Energy) Hervé Dzitko (Fusion for Energy) Kouki Hirosawa (National Institutes for Quantum Science and Technology) Kai Masuda (National Institutes for Quantum Science and Technology) Francesco Scantamburlo (IFMIF/EVEDA Project Team) Akihiko Mizuno (National Institutes for Quantum Science and Technology) Tomoya Akagi (National Institutes for Quantum Science and Technology) Fabio Cismondi (IFMIF/EVEDA Project Team) Dominique Gex (Fusion for Energy) Keitaro Kondo (National Institutes for Quantum Science and Technology)

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