I’m bothered by some of the media’s breathless, credulous coverage of recent events in fusion research. People are too excited; they’re forming incorrect conclusions.

This article from Science is one of the better ones I’ve seen on the subject.

What are the facts?

  • NIF has an inertial confinement reactor that shoots lasers at a pellet of hydrogen fuel; the goal is to ignite a fusion reaction.
  • In a recent NIF experiment, lasers shot ~2 MJ of energy into a fuel pellet. About 3 MJ came out… which is pretty exciting!
  • However, the lasers themselves required hundreds of MJ to operate during that single shot. So the reactor at NIF is nowhere close to a self-sustaining fusion reaction.
  • This experiment was the latest in a series of very similar NIF experiments in recent years. Its success resulted from (a) incremental improvements to the fuel pellet design and (b) increased power for the lasers.

What’s bothering me?

  • The fact that the reaction is not self-sustaining has not been given enough attention. A lot of people I talk to seem to have missed that crucial detail. I don’t blame those people for missing it. But I do blame journalists for not giving it more prominence in their coverage.
  • People keep calling this “revolutionary,” or a “breakthrough.” To me it seems more like an exciting—though incremental—improvement in inertial confinement fusion.
  • I’ve heard some people say that this experiment proves a scientific principle. They say it’s an existence proof that controlled fusion is possible. However, I don’t think there was any doubt controlled fusion was physically possible. The physics was never in question; it has always been fundamentally an engineering problem. And most of the engineering challenges remain unsolved.
  • A lot of the excitement seems misplaced given that inertial confinement reactors are unlikely to produce economically viable fusion. Most experts consider magnetic confinement devices (e.g., tokamaks or stellarators) much more promising for attaining self-sustaining fusion. I doubt the technological lessons learned at NIF will help improve magnetic confinement designs.
  • Some people say public excitement about these advances is a good thing, since it will result in increased funding for fusion research. That may be true. But if we still don’t have commercial fusion reactors in 10 or 20 years, tax-payers and investors may become resentful. That funding could quickly disappear if people feel that the researchers oversold and underdelivered.

I voice these concerns as somebody who is a big fan of fusion research. I wish it had more funding. But I think the discussion around recent events—by journalists and politicians—has been confused or dishonest.

\( \blacksquare\)