Scientific breakeven

The point where the fusion energy released exceeds the energy delivered to the fuel: a target gain above 1 for laser-driven fusion, or a plasma gain above 1 for magnetic confinement. Reached for laser fusion by the National Ignition Facility on 5 December 2022. Not yet reached for magnetic confinement: the best measured result with deuterium-tritium fuel is a plasma gain of 0.63 from JET on 31 October 1997, often quoted as 0.67 because a different figure for the heating power is used as the denominator. Higher figures quoted for other machines, such as JT-60U's, are equivalent gains: calculations for plasmas that contained no tritium. Distinct from engineering breakeven, which counts the whole plant's electricity rather than the energy delivered to the fuel.

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concept:scientific-breakeven

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