Regularization and Convergence of the Near-Axis Expansion

Explore a 19-minute talk by Max Ruth examining the numerical aspects of the near-axis expansion in stellarator physics. Learn how this technology has become essential within the Simons collaboration for efficiently investigating stellarator configurations, offering advantages in speed, usability, and simplified expressions for quasisymmetry. Discover the mathematical analysis showing that vacuum near-axis expansion can converge when properly regularized, while unregularized cases lack guaranteed convergence regardless of input conditions. See demonstrations of convergence with real coil fields and understand the potential relationship between convergence radius and axis-coil distance, similar to the L-grad-B metric. This presentation was delivered as part of the Simons Collaboration on Hidden Symmetries and Fusion Energy Annual Meeting 2025.