Gate: Plug Coil Stress

The burner's plug magnet is overstressed by roughly 3-3.9x at the design bore, making the machine infeasible as specified until the magnet is solved.

The magnet is the bottleneck

The tandem-mirror burner confines its plasma with very high magnetic fields: a 26.49 T plug and a 17 T throat. Producing 26.49 T over the required bore places the plug coil under mechanical stress far beyond what its structure can bear. In the design-and-simulation study the coil is overstressed by roughly 3-3.9x at the design bore.

A factor of 3-3.9x is not a tuning problem; it means the magnet as specified would fail structurally. The machine is therefore infeasible as currently specified. Closing this gate requires either a fundamentally different magnet approach, a changed field or bore, or materials and structures not yet in hand.

Why state it this plainly

Overstating magnet feasibility would undermine every downstream claim about resilience and logistics. Stating the 3-3.9x factor openly is what makes the rest of the analysis trustworthy: the resilience concept is real, and this is precisely the physics that must be solved before it can be pursued as hardware.

• Plug field 26.49 T, throat 17 T are extreme requirements
• Plug coil overstressed 3-3.9x at the design bore
• Not a tuning issue; the magnet fails as specified
• The machine is infeasible as specified until this is solved

A factor of 3-3.9x also sets the scale of what a solution must achieve: incremental material improvements do not close a threefold stress gap. Candidate paths, changed field or bore, fundamentally different magnet architectures, or advances in structural materials, must each be judged against that multiplier. Naming the multiplier precisely is what keeps the search for solutions honest rather than optimistic.

This is a design-and-simulation finding, stated without softening.