EMAIL: r-rosner@uchicago.edu
In the Bulletin interview (above), Dr. Rosner mentioned these IFE problems:
The idea of actually building an inertial fusion reactor based on the NIF design is, in my view, an even much more audacious notion than building a practical reactor based on magnetic field confinement.
To make that happen, you’d need to have fundamental technical revolutions in so many areas, including laser systems capable of generating shots at a pace of 10 Hertz (meaning 10 ignition events, or cycles, per second), energy extraction methods, and target fabrication rates of millions per day. Just mass-producing the capsule that exploded is a titanic challenge—as is the price. The fabrication cost of just that one test capsule was about $100,000, and you’d have to bring that down to tiny fractions of that cost.
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neutrons—which, being neutral, are not confined by the magnetic fields—hit the walls of the plasma chamber, causing dislocations which end up embrittling the metal of the walls. You don’t want an embrittled steel casing like that—the last thing you need are cracks. So that’s a problem.
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the driver behind the huge effort in materials science to solve this embrittlement problem, by (for example) inventing what are called “self-healing materials.” Biology has succeeded in making that invention—you get a cut, it heals over. But we haven’t figured out yet how to do that in the inorganic world.We still have to figure out how to construct alloys that basically repair themselves.
My doubts about fusion energy are expressed here, by Dr. Rosner:
While I think we will get to build magnetic confinement-based fusion power reactors (such as tokamaks) only in the distant future—meaning perhaps by the year 2100—I don’t think this will ever be the case for inertial fusion (such as NIF’s laser powered system). It will never be used as an energy source.
(shrugs, peels banana):
Yeah, so… I think the big disconnect here is everyone imagining ICF as this super-fragile, precision thing. BSF isn’t like that.
You pour a bunch of FLiBe glipity-glop glug-glug into a big sphere. It’s hot, and it’s happy. Just let it sit there. No rush, just wait.
Somewhere inside, there’s a bubble of fuel. How did it get there? It doesn’t matter, we just wiggle it around until it’s kinda near the middle. Close enough is close enough.
Then you pound on the outside of the sphere with giant acoustic hammers. Not delicate taps — more like one big thump.
When the acoustic waves get close to the center, you turn on the pump lights — full power!
The reactor works like an Easy-Bake Oven. Once it’s hot and sqeezed, ignition of the fuel is automatic. The bubble collapses, flashes, the light bounces around, comes back in, and things go boom without any need for perfect timing.
Neutrons? FLiBe absorbs them before they even get close to a wall. And, because FLiBe is a ‘self-healing’, low-Z, ionic, liquid salt, there is no need to worry about mechanical damage or dirty nuclear byproducts. When it heats up, just pump it through a heat exchanger. Material problems, SOLVED!
No expensive, precision targets. No babysitting. Just heat, shake, repeat.
So yeah
Rosner’s worries make sense for fragile fusion. BSF is the opposite. It’s robust and forgiving — the kind of reactor that just works even if you’re not paying attention.
The DOE published a list of core challenges anyone can vote on.