Engineering Gain (Q_eng)
Q_eng compares net electricity out to all electrical power in — the number that actually matters for a power plant. The Mode-D operating point closes at Q_eng = 3.9.
- Definition
- Net electric out ÷ total electric in
- Kronos operating point
- Q_eng = 3.9 (Mode D, exhaust-honest)
- Net electric
- 486 MWe per unit (0.61–0.84 GWe gated ceiling, labeled history)
- Enabled by
- Direct energy conversion (no Carnot ceiling)
While fusion gain (Q) measures the plasma, engineering gain (Q_eng) measures the plant: net electricity delivered to the grid divided by all the electricity the plant consumes — heating, current drive, magnets, cooling, and balance of plant. It is the number that determines whether a reactor is a power source or a power sink.
Kronos MetroVolt closes at Q_eng = 3.9 at the frozen Mode-D operating point — 486 MWe net on the exhaust-honest ledger — with the gated hot-ion ceiling ledgers (0.61–0.84 GWe, Q_eng ≈ 2.1–2.7) retained as labeled history. The key enabler is direct energy conversion: capturing charged-particle energy without a steam cycle removes the Carnot ceiling that caps a thermal plant's conversion efficiency, lifting the whole engineering-gain equation.