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In your first paragraph what are you even saying? If you make one complex fusion reaction work then a different one is cake? I don't think helions “smash the pl

by RC_ITR 3y ago

In your first paragraph what are you even saying? If you make one complex fusion reaction work then a different one is cake? I don't think helions “smash the plasma linearly” design even works for D-D. Their quartz containment chamber definitely is a weird set up for D-D. I’m aware of what Helion is trying to do and wish them luck, but they won’t even release data on their supposed He3 reactions, so I’m guessing they’re not light years ahead on D-D and ready to use their very customized tech for a different reaction quite yet. As for your very salient point on where the energy goes, what are you heating? Your new Tritium. So now you not only have to capture the tritium but you have to extract its heat to generate electricity? Or are you just capturing heat from the helium and whatever is absorbed by the rest of the blanket? No startups use a breeding blanket in 2023. They just talk about them. All the designs are still very much in prototype phase and nobody has blanket IP because they barely have reactor IP (though lots of cool magnet patents!) In fact if they did have breeding blankets, they could actually make some money selling their tritium!

DennisP 3y ago
It's just temperature, density, and confinement time. For each fuel, there's a minimum threshold temperature and a minimum triple product of those three parameters to get net power. The triple product is lower for D-D than it is for D-He3. For breeding tritium, everybody's focused on just getting net power right now but several companies are planning liquid breeding blankets. For CFS it's a molten FLiBe salt, a couple others are using molten lead-lithium. Either way, you run coolant pipes through it, and the new tritium will bubble out the top. Honestly it doesn't sound all that hard.
- RC_ITR 3y ago
  >It's just temperature, density, and confinement time. I know what a triple product is (even a Lawson criterion), but what you're saying is like saying curing cancer is just "figuring out how to turn off uncontrolled cell division." There's a lot of practical engineering that is behind that sneakily simple phrase. If D-D fusion is so easy, why don't the other start-ups pursue that since D is abundant and T is one of the rarest materials ever? In fact, since D-D makes T 50% of the time anyway, why don't they do both? As for the blankets, as I've said, plenty of people talk about them, but have never even come close to building one. >Honestly it doesn't sound all that hard. Yeah, I agree it doesn't sound very hard. By chance do you work at a VC firm?
  - DennisP 3y ago
    D-D requires a higher triple product than D-T fusion and produces less energy, so most companies go with D-T, and don't attempt to use D-D to produce the tritium. But D-D takes a lower triple product than D-He3, so if you can get net power from D-He3, then D-D is a fine way to produce the He3. Helion is the only company that thinks they can get net power from D-He3 so they're also the only company pursuing D-D for breeding.
    - RC_ITR 3y ago
      >D-D requires a higher triple product than D-T fusion and produces less energy, so most companies go with D-T, and don't attempt to use D-D to produce the tritium. Yes, because again, all the ways we know how to make Tritium are implausible from either an energy balance standpoint or a "where do we get all these energized neutrons" standpoint. That's always been my argument. >You don't need to breed He3 unless you can get net power from D-He3. If you can do that, then you can probably also get net power from D-D Going back to this, you're aware D-D results in 50% T and 50% He3, right? Helion relies on D-T fusion working so they can sell their "waste" Tritium (lol). None of these things you are claiming to be easy factually pencil out and that is why we are so far from commercial fusion.
      - DennisP 3y ago
        D-T: Where you get all those energized neutrons is easy: from D-T fusion. You need a neutron multiplier like lead or beryllium, then it looks like you can average about 1.15 tritium atoms per D-T reaction. Helion: to use their tritium they just have to wait. Tritium decays to He3 with a 12-year half-life. (Of course if they didn't want to use the tritium at all, it would just mean building twice as many D-D reactors and it'd still work. That'd be silly though.)

by RC_ITR 3y ago

DennisP 3y ago

It's just temperature, density, and confinement time. For each fuel, there's a minimum threshold temperature and a minimum triple product of those three parameters to get net power. The triple product is lower for D-D than it is for D-He3. For breeding tritium, everybody's focused on just getting net power right now but several companies are planning liquid breeding blankets. For CFS it's a molten FLiBe salt, a couple others are using molten lead-lithium. Either way, you run coolant pipes through it, and the new tritium will bubble out the top. Honestly it doesn't sound all that hard.

RC_ITR 3y ago
>It's just temperature, density, and confinement time. I know what a triple product is (even a Lawson criterion), but what you're saying is like saying curing cancer is just "figuring out how to turn off uncontrolled cell division." There's a lot of practical engineering that is behind that sneakily simple phrase. If D-D fusion is so easy, why don't the other start-ups pursue that since D is abundant and T is one of the rarest materials ever? In fact, since D-D makes T 50% of the time anyway, why don't they do both? As for the blankets, as I've said, plenty of people talk about them, but have never even come close to building one. >Honestly it doesn't sound all that hard. Yeah, I agree it doesn't sound very hard. By chance do you work at a VC firm?
- DennisP 3y ago
  D-D requires a higher triple product than D-T fusion and produces less energy, so most companies go with D-T, and don't attempt to use D-D to produce the tritium. But D-D takes a lower triple product than D-He3, so if you can get net power from D-He3, then D-D is a fine way to produce the He3. Helion is the only company that thinks they can get net power from D-He3 so they're also the only company pursuing D-D for breeding.
  - RC_ITR 3y ago
    >D-D requires a higher triple product than D-T fusion and produces less energy, so most companies go with D-T, and don't attempt to use D-D to produce the tritium. Yes, because again, all the ways we know how to make Tritium are implausible from either an energy balance standpoint or a "where do we get all these energized neutrons" standpoint. That's always been my argument. >You don't need to breed He3 unless you can get net power from D-He3. If you can do that, then you can probably also get net power from D-D Going back to this, you're aware D-D results in 50% T and 50% He3, right? Helion relies on D-T fusion working so they can sell their "waste" Tritium (lol). None of these things you are claiming to be easy factually pencil out and that is why we are so far from commercial fusion.
    - DennisP 3y ago
      D-T: Where you get all those energized neutrons is easy: from D-T fusion. You need a neutron multiplier like lead or beryllium, then it looks like you can average about 1.15 tritium atoms per D-T reaction. Helion: to use their tritium they just have to wait. Tritium decays to He3 with a 12-year half-life. (Of course if they didn't want to use the tritium at all, it would just mean building twice as many D-D reactors and it'd still work. That'd be silly though.)