The Mode M closing point.
Mode M is the burner's reproducible closing point — the operating condition where the D–³He tandem mirror produces more electricity than it consumes, and where every number reproduces from the shipped deposit.
- Engineering gain Q_E
- 1.31
- Neutron fraction f_n
- 5.44% — low-neutron, not aneutronic
- Operating point
- x(³He) 0.30 · Ti 90 keV · nₑ 2.6×10²⁰ m⁻³
- Net electric (55 / 440 / 1400 m)
- +104 / +850 / +2832 MWe
- Status
- Requirement-class — reproduces from the deposit solver
A burner "closes" when it delivers more electrical power to the grid than it draws to run itself — Q_E > 1. Mode M is the point Kronos froze as the reproducible closing design: at a helium-3 fraction of 0.30, ion temperature 90 keV, it reaches Q_E 1.31 with a neutron fraction of just 5.44%. It is called a closing point because it sits inside a whole window of closing conditions — 107 reproducible ones — and this is the one with the highest net power that does not push the plug requirement past what the physics endorses.
The intensive numbers — gain and cleanliness — are length-independent. What scales with the length of the central cell is total power. That single fact turns one design into a product line:
- 55 m (reference)
- 0.54 GW fusion → +104 MWe net
- 440 m — Aegis
- 4.3 GW fusion → +850 MWe net
- 1400 m — MetroVolt
- 13.7 GW fusion → +2832 MWe net
Mode M replaced two earlier figures that did not reproduce (the withdrawn Q_E 1.191 and 1.825), and it corrects the papers' unqualified Q_E 1.002 by stating it with its requirement. You can run the underlying solver yourself in the live simulation.