The following article has been published:
“An innovative superconducting magnetic cage concept for compact plasma with high NWL: Design and analysis”
Authors: Lorenzo Giannini, Cesar Luongo, Andrea Chiappa, Corrado Groth, Marco Biancolini, Christian Bachmann, Janos Bajari, Francesco Maviglia, Curt Gliss, Richard Kamendje, Gianfranco Federici.

This study presents the electromagnetic and structural design of a novel magnetic confinement system for a Volumetric Neutron Source (VNS), a compact fusion device targeting high neutron wall loading (NWL). The proposed architecture includes 12 Toroidal Field Coils (TFC), 6 Poloidal Field Coils (PFC), and a Central Solenoid (CS).

A key innovation is the internal placement of the PFCs inside the toroidal chamber, diverging from the external configuration used in ITER. This design choice significantly reduces the required poloidal current and improves plasma control, while introducing new structural and manufacturing challenges.

The toroidal field system is designed using the MADE optimization algorithm, defining the winding pack layout and conductor arrangement. An in-situ winding strategy is proposed to address assembly constraints. The coils are designed using either HTS tapes or react-and-wind Nb₃Sn strands, encased in 316LN stainless steel selected for its mechanical and thermal performance.

Electromagnetic analysis, carried out via a detailed ANSYS APDL model, evaluates field distribution and Lorentz forces on the coils. Structural assessments confirm that the TF coil casings remain within allowable stress limits under operational, cooldown, and dead weight conditions, with only minor localized exceptions.

The work involves the contribution of three researchers from the University of Rome Tor Vergata: Andrea Chiappa, Corrado Groth, and Marco Biancolini.

The full paper is available here.