Popular Mechanics: German Wendelstein Fusion Reactor ‘Actually Working’

Moving to the more traditional hot fusion world, there’s an article on the Popular Mechanics website which reports that the Wendelstein 7-X stellarator reactor is actually working according to plan, with a very small error rate.

The article is titled “Germany’s Wildly Complex Fusion Reactor Is Actually Working” and can be accessed here:

The main problem with the current model is that, like other hot fusion devices, it is not able to produce more energy than it consumes, and this was apparently understood by the inventors who built this as a proof-of-concept device. However, since this seems to have been a success, the design team can now move on with the job of trying to increase efficiency. If they can make a machine with a COP greater than 1, it would be a huge milestone for the hot fusion field.

  • sam
  • Pekka Janhunen

    Because energy is conserved, every fusion machine which produces even a tiny bit of fusion reactions obviously produces more energy than it consumes and therefore has “COP>1”. But the relevant question is whether the machine produces more electric energy than it consumes. Because the input energy of a hot fusion reactor is electric in nature, the machine should be able to produce more electricity than it consumes. Otherwise it’s a net consumer rather than net producer of electricity.

    For some reason, this misconception is repeated in almost every public outreach concerning hot fusion. Maybe because making a distinction between different forms of energy is perceived as too “technical” for “layman” readers. Unfortunately, however, that distinction is all that there is to it. Taking that distinction forcefully away simplifies the problem into absurdity.

    Theoretically, because hot fusion plasma is hot, one could convert the produced energy to electricity with efficiency which approaches 100% (Carnot efficiency plasma temperature minus room temperature divided by plasma temperature is almost 1.0). However, because the energy is liberated mostly as neutrons which are neutral particles, in practice the neutrons produced by the reaction would be just thermalised in the surrounding blankets and then electricity is produced by turbines. Their Carnot efficiency then depends on the temperature of the blankets, but is typically 30-40% as in fission plants.

    • Alain Samoun

      Also, it is a small part of the energy that is used to produce fusion,the remain is lost on heat and radiations in the machine.

  • sam

    I found an interesting article via Newsfusion Science News – I thought you might like it:

  • Warthog

    This point has been reached before (Bussard polywell). No usable reactors yet.

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  • Ophelia Rump

    By that standard any “energy producing device” that has any infinitesimal output “works”.

    Gravity wheel, yup for a moment.
    Now we can work on making it sustain!

    Isn’t science reporting wonderfully consistent?

  • bkrharold

    If they are lucky, it could even be used as a tea maker, but the tea would cost extra of course.

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