Deep Dive: The Magnet & Shield System
Kronos's 24.6 T graded, demountable REBCO magnet, its strain margin, and the compact center-stack shield that a low-neutron design makes possible.
- On-axis field
- 6.0 T
- Peak conductor
- 24.6 T at R_c = 1.40 m
- Strain margin
- 0.252% vs 0.40% (1.59×, S47)
- Gate
- G2
The magnet is the enabling technology of the whole design, and the center stack is where its hardest engineering lives. Kronos MetroVolt's toroidal-field coils produce 6.0 T on axis and a 24.6 T peak on the inboard conductor at R_c = 1.40 m — a peak-to-axis ratio of 5.
That field is carried by a graded, demountable REBCO winding pack. The grading tunes the conductor layer by layer to the local field, holding peak strain to 0.252% against the 0.40% irreversible limit — a 1.59× margin (analysis S47). Being demountable lets the pack open for maintenance and vessel access.
The center stack must fit both the inboard magnet leg and the neutron shield in minimal radial space — and this is where being low-neutron pays off, since a thinner shield suffices, freeing room for conductor. The 24.6 T envelope sits just above the demonstrated 24.4 T single-coil field and is adjudicated at the G2 gate.