Göttingen 2025 – wissenschaftliches Programm
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P: Fachverband Plasmaphysik
P 17: Poster Session II
P 17.7: Poster
Mittwoch, 2. April 2025, 16:15–18:15, ZHG Foyer 1. OG
Effect of stray magnetic fields on particles in the Wendelstein 7-X neutral beam box — •Lucas van Ham1, Samuel Lazerson2, Björn Hamstra3, Paul McNeely1, Norbert Rust1, Dirk Hartmann1, Sergey Bozhenkov1, and the W7-X Team1 — 1Max Planck Institute for Plasma Physics — 2Gauss Fusion GmbH, Germany — 3Eindhoven University of Technology
A new comprehensive model for calculating ion trajectories inside the neutral beam injection (NBI) system of Wendelstein 7-X (W7-X) is presented. The model consists of two parts: First, the magnetic materials code MUMAT calculates the magnetic response of ferritic materials (including NBI shielding) to the magnetic field produced by the main W7-X coil system. This code has been verified through application to a scenario with a known magnetic field. Second, the Monte Carlo particle following code BEAMS3D follows particles through the resulting magnetic field and estimates heat loads on NBI components.
MUMAT calculations of the magnetic field inside the NBI system predict significant fields (>10 Gauss) inside the NBI neutralizer, indicating that stray magnetic fields penetrate the NBI system. Subsequent BEAMS3D simulations predict that heat loads on NBI components shift vertically due to this neutralizer field. These shifts agree qualitatively with experimental observations, and a quantitative comparison with infrared imaging and calorimetry is planned.
The NBI system is essential for achieving high performance plasmas in W7-X, and this new model can help improve NBI reliability and develop paths towards longer NBI heat pulses.
Keywords: neutral beam injection; plasma heating; BEAMS3D; MUMAT; Wendelstein 7-X