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arXiv · 2509.13555

A Computational Picture of Hydride Formation and Dissipation In Nb SRF Cavities

Aiden Harbick·Mark Transtrum·Nathan Sitaraman·Tomás Arias·Matthias Liepe
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Abstract

Research linking surface hydrides to Q-disease, and the subsequent development of methods to eliminate surface hydrides, is one of the great successes of SRF cavity R&D. We use time-dependent Ginzburg-Landau to extend the theory of hydride dissipation to sub-surface hydrides. Just as surface hydrides cause Q-disease behavior, we show that sub-surface hydrides cause high-field Q-slope (HFQS) behavior. We find that the abrupt onset of HFQS is due to a transition from a vortex-free state to a vortex-penetration state. We show that controlling hydride size and depth through impurity doping can eliminate HFQS.

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Aiden Harbick, Mark Transtrum, Nathan Sitaraman, Tomás Arias, Matthias Liepe. 2025-09-16. A Computational Picture of Hydride Formation and Dissipation In Nb SRF Cavities. https://arxiv.org/abs/2509.13555

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