Development and Experimental Verification of a Strong Field Fan-Spine Magnetic Null Point Topology

This article presents the design, construction, and experimental testing of a strong field (≈0.1-1 T) fan-spine magnetic null point topology. Upcoming studies of 3-D magnetic reconnection in laboratory plasmas will require a scalable volume within which a 3-D fan-spine topology must be created and sustained to enable resolvable plasma dynamics. This study demonstrates the construction of one such 3-D fan-spine topology featuring a mathematically accurate spine axis. Low energy, constant current tests (< 1 mT) of multiwind test articles with thin high gauge wiring verify the structure and accuracy of the spine axis magnetic field. Using additive manufacturing techniques and pulsed direct-current capacitors, this article demonstrates the first qualification of a transient ≈0.6-T fan-spine topology. Subsequent high-energy, pulsed current testing of multiwind test articles with thick low-gauge wiring demonstrate the formation of ≈0.5-ms duration strong fields (≈0.8 T). Applications of these strong field 3-D null point topologies to next-generation plasma physics experiments of magnetic reconnection and astrophysical particle acceleration are discussed.