[sbierwagen]

Cool idea. Capital costs would certainly be lower than any of the magnetic confinement designs, if it works.

The power plant design they show has a 150MWe target power. Will be an interesting engineering challenge scaling it up and keeping all the finicky little parts and seals in the gun working when by design it's connected to a (small) nuclear explosion by a long pipe. If the timing is right you could have a heavy rotating shutter shielding the muzzle from the backblast.

[pencilguin]

They will, fortunately, not need to solve any of those problems, because there won't be any power plant. Instead, they will spend all the investors' money and then go do something else.

[Schroedingersat]

What's your take on Helion? They're acting exactly like every other scammer on the surface, but the more I dig the more I find evidence of thinking about things like how much quartz will evaporate and get into parts you don't want it to over 10 years. I can't see an overriding reason why it's immensely stupid like all the other schemes out there either.

[sbierwagen]

For a while they were describing D-He3 as "aneutronic", (that reaction is, but a mixed D-He3 plasma will be producing D-D side reactions, which produce neutrons) and some of their promotional materials showed reactors in standard ISO shipping containers. (missing the concrete biological shield it would need) However, I just checked their site again to link to those mistakes, and they've been removed, which is nice. Their CEO also made some nonsense remarks about how Helion reactors would be deployed directly to end users like datacenters, which the NRC wouldn't like.

They're a lot like the other fusion startups in the current scene. They have a machine, about which they make various surprising claims, but keep almost all the specifications secret, since it's a privately held venture rather than a public government-funded experiment. It's not obvious incoherent nonsense like solar roadways from a couple years back. Maybe it will work, maybe it won't. Check back in 10 years.

[DennisP]

The D-He3 reaction itself is aneutronic. Overall, Helion's reactor would produce only 6% of its energy as neutron radiation, compared to 80% for D-T reactors. For Helion that means they extract electricity directly from fast-moving charged particles instead of using a heat cycle. In practical terms that's often what people are thinking about what they refer to aneutronic fusion.

The NRC and their UK equivalent have already been moving towards lighter regulation for fusion reactors, and that's for D-T reactors. A reactor like Helion's could well be regulated more like medical devices than fission reactors.

[Schroedingersat]

I'd lump all the other fusion startups into the same category as incoherent nonsense like solar roadways as they all rely on recycling energy through a steam turbine (which is already prohibitive even if you had free heat) in order to power their rube goldberg machine and somehow that's supposed to be 100x cheaper than existing steam turbines when excluding the fuel.

I was wondering if there was some incoherent nonsense I'd missed.

[pencilguin]

Helion is the only fusion startup I know of that is not obviously a scam.

They count on D-D side reactions for neutrons to use breeding tritium, which decays over decades to the 3He they need. I don't see how that could produce enough. If not, their thing might still end up usable to power outer solar system space probes, using 3He decayed from the usual CANDU-produced tritium.

The Princeton FRC design is intended for spacecraft propulsion. I don't know if it is more or less practical.