Electronics > Projects, Designs, and Technical Stuff

Cracking the Fusion Nut

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moffy:
yeah, like a bomb went off :o :o :o
I guess that is some of the waste energy they have yet to deal with.

I must say that I have found the comments and discussion illuminating.

excitedbox:
I like the focus fusion method. They don“t need to boil water or anything to spin a turbine either. They create an alternating current directly. In a sort of foil ball. It is also by far the cheapest method. I think the main researcher comes off as kind of a nut from his appearance and that could be holding them back from getting real funding. I wish there was less politics etc. in research funding.

moffy:
I have to agree, I hope they get funding also. They have pioneered much of the theory, it is a shame that they can't progress to the next level.

pwlps:

--- Quote from: donotdespisethesnake on February 15, 2020, 11:49:19 pm ---Most of the energy output of the D-T reaction is in the form of fast neutrons? I think capturing those and turning them to heat on a GW scale is fairly hard.

--- End quote ---

This is why the Z machine approach might be interesting, it can reach high enough energies for aneutronic processes like the B-p fusion.

ejeffrey:

--- Quote from: donotdespisethesnake on February 15, 2020, 11:49:19 pm ---
--- Quote from: ejeffrey on February 15, 2020, 09:23:53 pm ---Getting the energy out isn't really that hard.  It's obviously not entirely trivial but if you can get the fusion part working with enough heat output building a power plant around it is not going to be the obstacle.

--- End quote ---

Most of the energy output of the D-T reaction is in the form of fast neutrons? I think capturing those and turning them to heat on a GW scale is fairly hard.
A lot of the steps look doable on paper or in a lab, but putting it all together in a working power plant is something we just don't know until we've tried.

--- End quote ---

Depends on what you mean.  Slowing down neutrons and capturing the heat isn't really that hard.  After all, we do that in fission too.  The fusion neutrons are higher energy (about 7x higher KE), but slowing them down still isn't a problem.

The issues with DT fusion in particular are that the neutrons tend to destroy the reactor and create radio isotopes in the process.  While DT fusion doesn't have any risk of meltdown like a fission reactor, it still creates a large quantity of radioactive waste.  The other problem is that a DT fusion reactor needs to produce tritium to complete its fuel cycle.  Some of the fast neutrons have to be captured to produce tritium -- and it is a lot.  You need a net tritium yield of 100% -- every fusion event produces 1 neutron which must produce on average 1 tritium nucleus to replace the one used.  Lithium 7 can produce multiple tritium from a single high energy neutron, but you still must capture a significant fraction of the the neutrons in your lithium blanket, and that has to fit along with your magnets, lasers, power supplies, or whatever else you need to confine and generate the fusion.

P-B fusion gets rid of most of these disadvantages--it produces minimal neutrons, its inputs are naturally occurring, and poses no proliferation risk.  However, the ignition temperature is 10x higher and the electron number (and therefore bremsstrahlung losses) are much higher as well.

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