3 ms·

TEGs are pretty neat, but the temperature and energy flux is very hard on the materials. If only there was some way to get energy from a fusion reaction via a

TEGs are pretty neat, but the temperature and energy flux is very hard on the materials. If only there was some way to get energy from a fusion reaction via a semiconductor junction by running them in parallel at low temperature rather than in series at extremely high temperature, and a long way away so the neutrons could thermalize and you could absorb much easier to handle photons. Oh well.

ncmncm 4y ago
Where do the photons come from?
- Schroedingersat 4y ago
  The usual place. Surround your fusion reactor in a very thick blanket of opaque hydrogen plasma so the neutrons can bump into something. Contain the whole thing in some kind of force field (if only there was some alternative to the EM force for this purpose), then when the photons hit your photon electric generators you get electricity. If you arrange things such that the outside of the opaque hydrogen blanket is about 5800 Kelvin and your photon-electric generator panels are spread out in parallel to...let's say about a kilowatt of energy per square metre they should last a couple of decades and your efficiency will be okay, maybe around 20-30% There. Fusion power plant invented. Sadly it's just a pipe dream though because we couldn't roll it out without first waiting for a stable fusing plasma source on earth.
  - ncmncm 4y ago
    How does neutrons bumping protons produce light?
    - Schroedingersat 4y ago
      It heats them up (The joke is I'm describing the sun and solar panels as the end state of trying to overcome the technical hurdles of building a heat engine to extract electricity from fusion if you're not just playing along). Jokes aside, TEGs are pretty neat. In addition to harvesting what is currently waste heat in someplaces or having applications in geothermal or solar collectors they might even make fission not-stupid. Can't forsee any way fusion works as practical power generation this century though. It has worse power density than chemical and much higher temperatures to deal with and much higher neutron flux than fission as well as needing massive 2 kelvin magnets right next to the 100 million degree plasma that explode if they warm up to 3 kelvin.
      - ncmncm 4y ago
        Solar fusion doesn't produce neutrons hot or otherwise. It produces gamma rays, helium nuclei, and neutrinos.
  - pfdietz 4y ago
    > Surround your fusion reactor in a very thick blanket of opaque hydrogen plasma so the neutrons can bump into something. If you compute how thick that plasma would have to be to stop neutrons you'll realize this idea is totally unworkable.
pmayrgundter 4y ago
I'm exploring such a concept, NanoFusion. A study device and thinking from first principles about the reaction. There are higher energy reactions like proton-boron that emit only light and charged particles. Eric Lerner's Focus Fusion approach taught me about that. I'm looking at parallel delivery of single photons and how that scales as laser systems develop. Lasers themselves are on an exponential curve, so that seems promising. Fusion batteries would be cool! https://docs.google.com/document/d/1B5maRx9w0ahQTqSe6UZ56rd0P4M3pB3RTI1lQBhYRUw/edit?usp=drivesdk https://docs.google.com/document/d/1B5maRx9w0ahQTqSe6UZ56rd0...
- ncmncm 4y ago
  Sustained p-11B fusion might not be possible: the gamma photons carry away too much energy, and nothing can reflect them back. But if it could be made to work, it would be a better prospect than D-T.
  - pmayrgundter 4y ago
    Two ideas: 1) don't try to achieve a chain reaction, but do single atom reactions and fully cycle the energy. Simpler to think about, and raw energies add up (see link). 2) if chain reaction needed, orient the reaction to aim the outputs towards their secondary targets e.g. with a crystal lattice fuel package.

ncmncm 4y ago

Where do the photons come from?

Schroedingersat 4y ago
The usual place. Surround your fusion reactor in a very thick blanket of opaque hydrogen plasma so the neutrons can bump into something. Contain the whole thing in some kind of force field (if only there was some alternative to the EM force for this purpose), then when the photons hit your photon electric generators you get electricity. If you arrange things such that the outside of the opaque hydrogen blanket is about 5800 Kelvin and your photon-electric generator panels are spread out in parallel to...let's say about a kilowatt of energy per square metre they should last a couple of decades and your efficiency will be okay, maybe around 20-30% There. Fusion power plant invented. Sadly it's just a pipe dream though because we couldn't roll it out without first waiting for a stable fusing plasma source on earth.
- ncmncm 4y ago
  How does neutrons bumping protons produce light?
  - Schroedingersat 4y ago
    It heats them up (The joke is I'm describing the sun and solar panels as the end state of trying to overcome the technical hurdles of building a heat engine to extract electricity from fusion if you're not just playing along). Jokes aside, TEGs are pretty neat. In addition to harvesting what is currently waste heat in someplaces or having applications in geothermal or solar collectors they might even make fission not-stupid. Can't forsee any way fusion works as practical power generation this century though. It has worse power density than chemical and much higher temperatures to deal with and much higher neutron flux than fission as well as needing massive 2 kelvin magnets right next to the 100 million degree plasma that explode if they warm up to 3 kelvin.
    - ncmncm 4y ago
      Solar fusion doesn't produce neutrons hot or otherwise. It produces gamma rays, helium nuclei, and neutrinos.
- pfdietz 4y ago
  > Surround your fusion reactor in a very thick blanket of opaque hydrogen plasma so the neutrons can bump into something. If you compute how thick that plasma would have to be to stop neutrons you'll realize this idea is totally unworkable.

pmayrgundter 4y ago

I'm exploring such a concept, NanoFusion. A study device and thinking from first principles about the reaction. There are higher energy reactions like proton-boron that emit only light and charged particles. Eric Lerner's Focus Fusion approach taught me about that. I'm looking at parallel delivery of single photons and how that scales as laser systems develop. Lasers themselves are on an exponential curve, so that seems promising. Fusion batteries would be cool! https://docs.google.com/document/d/1B5maRx9w0ahQTqSe6UZ56rd0P4M3pB3RTI1lQBhYRUw/edit?usp=drivesdk https://docs.google.com/document/d/1B5maRx9w0ahQTqSe6UZ56rd0...

ncmncm 4y ago
Sustained p-11B fusion might not be possible: the gamma photons carry away too much energy, and nothing can reflect them back. But if it could be made to work, it would be a better prospect than D-T.
- pmayrgundter 4y ago
  Two ideas: 1) don't try to achieve a chain reaction, but do single atom reactions and fully cycle the energy. Simpler to think about, and raw energies add up (see link). 2) if chain reaction needed, orient the reaction to aim the outputs towards their secondary targets e.g. with a crystal lattice fuel package.