Magnet Winding and Jointing
REBCO coils are wound from finite tape lengths, so joints, bend radius, and turn insulation are manufacturing constraints on the whole magnet.
Building a coil from tape
A REBCO magnet is not drawn as a single wire; it is wound from stacked or cabled coated-conductor tapes of finite length. This introduces two manufacturing realities the design must respect: a minimum bend radius set by strain in the REBCO layer, and electrical joints wherever tape lengths meet.
Joints are a reliability item
Every joint adds resistance, which adds heat load at cryogenic temperature and a potential quench initiation site. Joint count, placement, and quality are tracked as a reliability metric. Where possible joints are placed in lower-field regions and made accessible, because a bad joint deep in the center stack is effectively unrepairable.
Winding constraints
- Minimum bend radius from REBCO strain limit governs coil geometry.
- Turn-to-turn insulation must survive the radiation and thermal environment.
- No-insulation or partial-insulation schemes trade quench robustness against ramp behavior.
- Joint resistance budgets the cryogenic heat load.
Why it feeds the schedule
Winding and jointing are where magnet design meets factory reality. The supply chain must deliver qualified tape in usable lengths, and the winding process must be repeatable across the FOAK, NOAK, and BOAK units. Manufacturing repeatability, not a single hero coil, is what the learning curve requires.
Insulation choices
Turn insulation must transmit load, survive the neutron and gamma dose near the plasma, and tolerate cooldown strain without cracking. Some designs reduce or omit turn-to-turn insulation to gain quench robustness and simplicity, at the cost of controllability during ramps. The insulation decision therefore couples directly to the quench-protection and structural strategies.
This page documents a design and simulation study, not a built machine. Construction begins Q2 2027; first-of-a-kind first tritium is targeted near 2030. Figures are computed, reproducible targets, not measurements.