Impact of mechanical tolerances on partial turn skipping in helical flux compression generator

Journal Article · 14 November 2024 · AIP Advances

DOI: https://doi.org/10.1063/5.0239004 · OSTI ID:2481652

Schriner, K.  ^[1]; Fryar, N.  ^[1]; Watson, T.  ^[1]; Stephens, J.  ^[1]; Dickens, J.  ^[1]; Young, A. ^[2]; Neuber, A.  ^[1]

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1. Texas Tech Univ., Lubbock, TX (United States)
2. Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)

Maintaining tight mechanical tolerances of the components used in helical flux compression generators is crucial for optimizing device performance. Moving beyond current literature, which provides various approximations for acceptable tolerances, a 3D simulation of the armature stator interaction during generator operation was developed, revealing that existing equations frequently misestimate the tolerance limits. Without restricting the generality of the presented approach, the focus was primarily on the armature’s concentricity and roundness, comparing the acceptable tolerance limits between generators of different sizes. An analytical approach for select geometries was developed, confirming the 3D results. Quantitative results reveal that a steeper Gurney angle and increased winding pitch allow for less restrictive tolerances for eccentricity and ellipticity. Even small deviations from the ideal armature positioning and shape will result in fluctuations of the output current time-derivative, observed experimentally and in simulation. Larger deviations then cause partial turn skipping, associated with loss of magnetic flux. The simulation elucidates the impact of tolerance deviations on generator performance by offering precise tolerance ranges for various generator sizes, thereby facilitating informed design decisions.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: AC52-07NA27344
• OSTI ID: 2481652
• Report Number(s): LLNL-JRNL--869342; 1104350
• Journal Information: AIP Advances, Journal Name: AIP Advances Journal Issue: 11 Vol. 14; ISSN 2158-3226
• Publisher: American Institute of Physics (AIP)Copyright Statement
• Country of Publication: United States
• Language: English