[HN Gopher] A primer to nuclear fusion and First Light Fusion
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A primer to nuclear fusion and First Light Fusion
Author : gtzi
Score : 27 points
Date : 2022-10-15 19:22 UTC (3 hours ago)
(HTM) web link (startuppirate.substack.com)
(TXT) w3m dump (startuppirate.substack.com)
| ohiovr wrote:
| "There are three boxes we need to tick, in order to overcome this
| repulsion I mentioned before and get the nuclei very close. And
| this is not an easy feat. We need high temperature (think a
| hundred million degrees), high density (have a lot of these
| nuclei in a very small space), and keep the nuclei in that small
| space long enough for them to "react". "
|
| High temperatures are usually used because the nuclei must have a
| lot of force to counter that of the liked charged partner. The
| most obvious way to do this is with heating the plasma because
| individual particles, when they collide head on, can have the
| combined momentum to plow their way together.
|
| But Philo T Farnsworth found a clever way to get them close with
| electrostatic forces. If it weren't for those darned wires.
|
| With millions of degrees that plasma viciously expands. An even
| more incredible contraction force must be used to keep this
| together long enough for "interesting results". This is done with
| inertial confinement like the Hbomb or emulations of it. Magnetic
| confinement merely slows the expansion, but it must at some point
| touch the walls.
|
| Actually, heat is not wanted. You only need to get the nuclei
| close enough that they quantum tunnel to each other to relieve
| their own stress in their environment. 2 Dueterons spread farther
| than helium3 does. Think of it like phase changes in condensed
| matter. Except we don't care at all about electrons, simply move
| them somewhere that the fuel ions wish to congregate at.
| Fortunately this can be a single point, as charges are
| concentrated on pointy things, as Faraday found in his
| experiments. The other side is full of the fuel ions. They don't
| have to be hot but warming them a little in an environment that
| is under 770 giga-pascals of pressure might be enough to moderate
| a nuclear combination process. It isn't hard to create two
| chambers in a crystal and make them undergo reductions or
| oxidations to free ions or electrons (tragically this happens
| with lithium ion batteries all the time). If they are surrounded
| in an environment that is very hard, very good dielectric
| strength, ions or electrons can be freed with no where to go.
| This is known as a meta-stable state and many crystal patterns
| exhibit this. The best dielectric known is diamond and it's also
| the hardest and has a ton of other helpful properties. If diamond
| couldn't do this, then nothing can. A mad genius with money and
| time would not have to go further than it to rule it out
| completely.
|
| Say my fancy idea doesn't work, if colliding macro projectiles is
| something useful to the author have they tried something like
| levitating pyrolytic carbon and propelling it with laser
| ablation? It could be done in a loop if part of the magnet can
| de-energize fast enough to allow the tiny block of carbon to
| escape.
|
| The plan they have seems very Wile E. Coyote to me but fun and
| cool. I hope they succeed.
| raydiatian wrote:
| One thing I don't understand about fusion is the mechanics of
| gain factors. If we can achieve a fusion reactor with a very
| small gain factor of say 1.01, is that sufficient to kick off an
| energy revolution, or do we need something more extreme like 10x
| or 100x?
|
| I suppose it boils down to what the "saturation threshold" of
| nuclear reactors is, where you can't pump more energy in without
| breaking the thing.
|
| In any case, what are the benchmarks that engineers are shooting
| for?
| Game_Ender wrote:
| Lots of interesting fusion startups. This group is using a gun
| type design that reminds of the Fat Man atomic bomb [0]. Except
| here it's a fusion target hit by high speed slug causing is to
| rapidly compression and undergo fusion. The key things is that
| unlike the NIF they have a clear path to power extraction. In
| production they are planning to use a chamber with circular
| sheets of falling liquid lithium to capture the fusion neutrons
| then transfer the heat [1]. Breeding some tritium along the way.
|
| 0 - https://en.wikipedia.org/wiki/Gun-type_fission_weapon
|
| 1 - https://firstlightfusion.com/technology/power-plan
| sbierwagen wrote:
| 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.
| legohead wrote:
| I've asked before but didn't get an answer. If we can achieve
| stable fusion, what are the plans for getting the power out?
|
| The guy in the article said you just do the same thing as coal or
| any other plant - generate steam. But we're talking about
| millions of degrees vs a couple thousand. Does it really scale
| that simply?
| raydiatian wrote:
| Haha. Stable fusion. Stable diffusion. I get it.
| DennisP wrote:
| Plasma temperature is high but total heat is similar to other
| power plants. The atoms are moving fast but there aren't many
| of them. So basically, surround the plasma with a neutron-
| absorbing coolant and you're good. CFS uses molten FLiBe salt,
| and some others use a molten mix of lead and lithium. Then you
| run water pipes through that.
| chihuahua wrote:
| I'm just guessing, but I imagine if you have a way of
| maintaining something at a temperature of millions of degrees,
| there's always a way to transfer that heat to some other thing.
| For example, by moving a gas past the very hot object, thus
| heating up the gas, and then moving the gas through a more
| conventional heat exchanger, where you generate steam for a
| steam turbine. Depending on the speed of the gas, it absorbs
| energy but isn't necessarily heated to the same temperature of
| millions of degrees, so it doesn't destroy the heat exchanger.
|
| I think this is somewhat similar to how a fission reactor is
| used to drive a steam turbine in an ordinary nuclear (fission)
| power plant.
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