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Found it: "Energy turnover is defined as the amount of heat multiplied by the duration of the discharge[1]." By "amount of heat" I assume they mean "heating power delivered to the plasma" b/c the the only way to multiply by time and get Joules is to start with power.
1: https://gigazine.net/gsc_news/en/20230227-wendelstein-7-x-en...
> The energy turnover results from the coupled heating power multiplied by the duration of the discharge
The numbers:
> The energy turnover of 1.3 gigajoule was achieved with an average heating power of 2.7 megawatts, whereby the discharge lasted 480 seconds
Also:
> Within a few years, the plan is to increase the energy turnover at Wendelstein 7-X to 18 gigajoules, with the plasma then being kept stable for half an hour
i.e. 10 megawatts for 30 minutes
Ie, would it be feasible in a power plant scenario to settle for 30-60 minutes of stability, and just restart?
I lost money on the endeavor, though.
There has never been a net-positive-energy magnetic confinement fusion experiment. Inertial confinement fusion has had 2 events that were "more energy out of the fuel than delivered to the fuel." But is still about a factor of 100 away from what is needed for "more electricity in than out"