jrvz wrote: ↑
Fri Sep 16, 2022 1:11 am
I've been studying one of the Helion patents https://patentimages.storage.googleapis ... 1811A1.pdf
. and have some questions...
In Fig. 3:
The "80 percent" refers to the fraction of energy, the fraction of reactions, the fraction of He-3, or what?
80 percent and 4 percent don't add up to 100 percent, so where is the other 16 percent?
The He-3 from the first reaction listed is shown re-entering the burn chamber then exiting again. Is this indicating that some of the He-3 is fused to He-4 before it even leaves the chamber?
The D-D reactions are described as "side" reactions, so most of the energy comes from D + He-3? How can enough He-3 be produced for the system to be self-sustaining? Especially since any T must be stored for something like eleven years, to allow it to decay to He-3?
A couple of things:
1. The patent is pretty old and some things have changed since then.
2. The patent is held fairly broad to allow them some wiggle room with what they are doing.
To my understanding, 80% refers to the energy in charged particles that can be used for direct conversion to electricity.
4% would be neutrons. The rest is likely X-Rays, some thermal losses and other minor losses that can not be recovered easily.
Yes, they breed He3 from D-D reactions. That He3 is then fed back in as fuel. D-He3 is aneutronic and does result is higher energy charged particles (14.7 MeV Protons and 3.67 MeV He4) than the D-D reaction. So that is why they do that.
The last I heard, they are planning to have Two D-D reactions for every D-He3 reaction. One of the D-D reactions results in a He3 and a neutron. The other in a Triton and a proton. The Tritium gained that way will eventually decay into more He3 that they can use as fuel for future power plants or just sell and trade for He3 on the free market (both isotopes have about the same market value, currently anyway).
They could theoretically surround the reactor with a Lithium blanket, which would yield them some extra power at the divertor and extra Tritium for trading (or decaying). I believe that they are currently not planning to do that however.