Deep Dive: The Hot-Ion Posture
Running the ions hotter than the electrons raises fusion output and limits losses — a real upside Kronos treats as a bet, with the near-thermal case as the operating baseline.
- Condition
- T_i/T_e ≥ 1.5 (prediction P2)
- Ceiling (gated, labeled history)
- P_fus 2.41 GW, P_net 0.84 GWe
- Baseline (Mode D)
- near-thermal Ti = Te = 48 keV; P_fus 1.22 GW, P_net 486 MWe
- Bound
- channeling redress ≤ ~30%
Fusion rate rises with ion temperature, while radiation losses concentrate in the electrons — so running the ions hotter than the electrons (T_i/T_e > 1) buys more fusion for less loss. The Mode-C-era posture targeted central temperatures of 65–70 keV (ions) against 34 keV (electrons), and the physics helps: raising T_i/T_e lifts the ITG turbulence threshold about 1.3×.
Crucially, Kronos states this as a ceiling, not a baseline. The hot-ion ceiling reaches P_fus ≈ 2.41 GW and P_net ≈ 0.84 GWe — but a full Spitzer equilibration analysis (S61) found the hot-ion posture is not sustainable at that ceiling, and the channeling redress of the hot-ion "tax" is bounded at about 30% even at perfect efficiency (S72).
So the honest operating baseline — ratified 24 July 2026 as the frozen Mode-D point — is near-thermal (T_i = T_e = 48 keV): P_fus = 1.22 GW, P_net = 486 MWe on the exhaust-honest ledger. Kronos plans and prices to that baseline and treats the hot-ion upside as something to be earned at the G1 gate (prediction P2).