Fusion! No, Really This Time

Andrew Donaldson

Born and raised in West Virginia, Andrew has since lived and traveled around the world several times over. Though frequently writing about politics out of a sense of duty and love of country, most of the time he would prefer discussions on history, culture, occasionally nerding on aviation, and his amateur foodie tendencies. He can usually be found misspelling/misusing words on Twitter @four4thefire and his food writing website Yonder and Home. Andrew is the host of Heard Tell podcast. Subscribe to Andrew's Heard Tell SubStack for free here:

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14 Responses

  1. fillyjonk says:

    Yeah no I remember the “cold fusion breakthrough” of like 1988 that turned out to be a hoax, I refuse to get excited for this until there are actually effective reactors being installed.Report

  2. Marchmaine says:

    Very nice. So, what, about a decade away?Report

  3. North says:

    The last two paragraphs give the game away. *sad sigh*
    It doesn’t matter if the math on the chalkboard says “energy out > energy in” unless we can harvest the energy out. Call me when “usable energy out > usable energy in” shows up.Report

    • Michael Cain in reply to North says:

      Even worse, reports are that the measurement is laser output energy compared to fusion energy output. The current laser system is about 1% efficient, so measured in terms of electricity in they’re still about 100x short of breakeven.Report

      • North in reply to Michael Cain says:

        Sleight of hand doesn’t work on physics damnit!Report

        • Michael Cain in reply to North says:

          Here later in the afternoon, I am given to understand that this is a normal way of making the calculation, in order to separate the fusion physics from the efficiency of a particular laser technology. New high-power laser tech is supposed to provide a 10x gain in laser efficiency at some point in the not too distant future. But the NIF may not be funded to replace their lasers for a long time.

          With my old systems analyst hat on, this is an example of why it’s hard to make predictions about future complex systems base on current technology. Another example: everyone assumes that the coolant used to keep the fusion reactor chamber walls from melting will be liquid lithium in the long run. Lots of advantages if you can make it work. But nobody’s ever done it at the necessary scale.Report

  4. scientists have been able for the first time to produce a fusion reaction that creates a net energy gain

    They’ve apparently never heard of the H-bomb.Report

    • Is this true? Serious question. The energy input for the fusion reaction is a fission bomb, and much/most of the total energy is a fission reaction driven by the high neutron flux of a fusion stage. Is the energy output of the fusion reaction greater than that of the fission first stage, or is it “merely” a side effect where the important part is the neutron flux?Report

      • Still, the fusion reaction is a net positive, no?Report

        • I don’t know, that’s what I was asking. AIUI, the design goal for the fusion stage in a thermonuclear weapon is not the energy released, it’s the neutron flux that causes a massive secondary fission reaction.

          You swap some number of ~180 MeV fissions in order to get some number of ~14 MEV fusion neutrons each with the potential to cause an ~180 MeV fission. All in a complicated arrangement where geometry and microsecond timing matters. I don’t know whether the energy output of the fusion reactions without the magnifying effect of the second fission stage exceeds the energy output of the initial fission stage or not.

          If you asked me to bet, I’d bet that the actual answer is classified at a level that they’re never going to tell me. I don’t know what sort of odd weapons security clearances you might hold :^)Report

          • It’s not something I’m allowed to discuss, of course.Report

          • Peter Moore in reply to Michael Cain says:

            That is a great question: I never considered that. As a tentative answer, a wikipedia article on ‘boosted fission weapon’ (evidently the more compact name used instead of fission-fusion-fission) claims less than 1% of the energy comes from the fusion itself.Report

            • It didn’t seem worth any more discussion last week, but after further reading the Tsar Bomba built by the Soviet Union omitted all the fissionable material except in the primary. Estimates are 97% of the 50 megaton energy release was from the fusion reactions. Side note: because of the high fusion yield the Tsar Bomba was, kiloton for kiloton, the lowest-fallout nuclear weapon ever detonated.

              Anyway, credit to Mr. Schilling. There’s been at least one previous historical instance of Q>1.Report