Fusion Gain (Q)

Q is the ratio of fusion power produced to heating power supplied. Kronos is honest that its endpoint is a driven system, not an igniting one.

Definition

Q = fusion power ÷ external heating power

Break-even

Q = 1

Ignition

Q → ∞ (self-sustaining)

Kronos endpoint

Driven: Q_plasma ≈ 2.4–2.9

Fusion gain (Q) is the headline efficiency of a fusion plasma: the ratio of the fusion power it produces to the external power used to keep it hot. Q = 1 is scientific break-even; Q → ∞ is ignition, where fusion self-heating alone sustains the burn with no external input.

Kronos describes its physics honestly as a driven system rather than an igniting one. At the aneutronic p–¹¹B endpoint the plasma gain closes at Q_plasma ≈ 2.4–2.9 — the fusion power is a healthy multiple of the input, but the reaction is sustained by continuous heating, not self-ignited. Q is distinct from the plant-level engineering gain, which counts net electricity out versus all power in.