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Fusion hype

Posted: Mon Feb 24, 2020 10:12 pm
by Grumble
https://newatlas.com/energy/hb11-hydrog ... an-energy/

Radically new approach to nuclear fusion could leapfrog all existing fusion tech. However the big caveat is a long way down the article:
First milestone is demonstrating the reactions, which should be easy
Say what? FFS. If it’s that easy then demonstrate it before you go bragging to the press about how awesome your new approach is.

Re: Fusion hype

Posted: Mon Feb 24, 2020 10:14 pm
by dyqik
But that won't get those ex-Theranos investors onboard.

Re: Fusion hype

Posted: Mon Feb 24, 2020 10:24 pm
by Grumble
I would absolutely love it if someone makes a new and better way to achieve fusion, but that article is like boasting that you’ve got a radical new way to build a race car with 3 wheels that’s going to smash Le Mans before you’ve even built the factory to make it.

Re: Fusion hype

Posted: Tue Feb 25, 2020 5:48 am
by jimbob
Grumble wrote:
Mon Feb 24, 2020 10:24 pm
I would absolutely love it if someone makes a new and better way to achieve fusion, but that article is like boasting that you’ve got a radical new way to build a race car with 3 wheels that’s going to smash Le Mans before you’ve even built the factory to make it.
Yup, and elsewhere, (The IET magazine about a decade ago) they had an interview with the head of one of the fusion projects (I think JET) where he stated that achieving break-even was the easy part. With the then-current materials technology, any such plant would need replacing every 18-months.

Re: Fusion hype

Posted: Tue Feb 25, 2020 8:03 am
by Gfamily
Did it explain how the 'alpha particles ... would create an electrical flow that can be channeled almost directly into an existing power grid'?

Re: Fusion hype

Posted: Tue Feb 25, 2020 9:31 am
by shpalman
Gfamily wrote:
Tue Feb 25, 2020 8:03 am
Did it explain how the 'alpha particles ... would create an electrical flow that can be channeled almost directly into an existing power grid'?
If they're all going in the same direction then you've got a flux of charged particles i.e. a current. Of course, usually an electrical current is a huge number of particles moving slowly (in a metal wire it's roughly one electron per atom moving at the order of a millimetre per second) and here there will be a very small number moving very quickly, so good luck doing something useful with that. You'll probably want them to move through a coil of wire to induce a more sensible current, or something.

Re: Fusion hype

Posted: Tue Feb 25, 2020 10:25 am
by jaap
shpalman wrote:
Tue Feb 25, 2020 9:31 am
Gfamily wrote:
Tue Feb 25, 2020 8:03 am
Did it explain how the 'alpha particles ... would create an electrical flow that can be channeled almost directly into an existing power grid'?
If they're all going in the same direction then you've got a flux of charged particles i.e. a current. Of course, usually an electrical current is a huge number of particles moving slowly (in a metal wire it's roughly one electron per atom moving at the order of a millimetre per second) and here there will be a very small number moving very quickly, so good luck doing something useful with that. You'll probably want them to move through a coil of wire to induce a more sensible current, or something.
I reckon that of all the energy released by fusing two hydrogen atoms into a helium atom, the amount contained in the fact that you have separated the resulting helium nucleus from its electrons is negligable.
It's as if they were running a diesel generator and then creating electricity by hanging a microphone off it.

Re: Fusion hype

Posted: Tue Feb 25, 2020 10:50 am
by Boustrophedon
jaap wrote:
Tue Feb 25, 2020 10:25 am
shpalman wrote:
Tue Feb 25, 2020 9:31 am
Gfamily wrote:
Tue Feb 25, 2020 8:03 am
Did it explain how the 'alpha particles ... would create an electrical flow that can be channeled almost directly into an existing power grid'?
If they're all going in the same direction then you've got a flux of charged particles i.e. a current. Of course, usually an electrical current is a huge number of particles moving slowly (in a metal wire it's roughly one electron per atom moving at the order of a millimetre per second) and here there will be a very small number moving very quickly, so good luck doing something useful with that. You'll probably want them to move through a coil of wire to induce a more sensible current, or something.
I reckon that of all the energy released by fusing two hydrogen atoms into a helium atom, the amount contained in the fact that you have separated the resulting helium nucleus from its electrons is negligible.
It's as if they were running a diesel generator and then creating electricity by hanging a microphone off it.
Correct, the energy is in the kinetic energy of the alpha particle, which being charged can have that energy captured electromagnetically, with perhaps some efficiency. If it were not charged you could only catch that energy as heat.

Re: Fusion hype

Posted: Tue Feb 25, 2020 10:54 am
by jaap
Boustrophedon wrote:
Tue Feb 25, 2020 10:50 am
jaap wrote:
Tue Feb 25, 2020 10:25 am
I reckon that of all the energy released by fusing two hydrogen atoms into a helium atom, the amount contained in the fact that you have separated the resulting helium nucleus from its electrons is negligible.
It's as if they were running a diesel generator and then creating electricity by hanging a microphone off it.
Correct, the energy is in the kinetic energy of the alpha particle, which being charged can have that energy captured electromagnetically, with perhaps some efficiency. If it were not charged you could only catch that energy as heat.
Thanks, that makes mores sense.

Re: Fusion hype

Posted: Tue Feb 25, 2020 10:58 am
by shpalman
jaap wrote:
Tue Feb 25, 2020 10:25 am
shpalman wrote:
Tue Feb 25, 2020 9:31 am
Gfamily wrote:
Tue Feb 25, 2020 8:03 am
Did it explain how the 'alpha particles ... would create an electrical flow that can be channeled almost directly into an existing power grid'?
If they're all going in the same direction then you've got a flux of charged particles i.e. a current. Of course, usually an electrical current is a huge number of particles moving slowly (in a metal wire it's roughly one electron per atom moving at the order of a millimetre per second) and here there will be a very small number moving very quickly, so good luck doing something useful with that. You'll probably want them to move through a coil of wire to induce a more sensible current, or something.
I reckon that of all the energy released by fusing two hydrogen atoms into a helium atom, the amount contained in the fact that you have separated the resulting helium nucleus from its electrons is negligable.
It's as if they were running a diesel generator and then creating electricity by hanging a microphone off it.
Wait a minute if I manage to get a proton to fuse with boron-11 (which is stable) aren't I just going to end up with stable carbon-12? Or do they expect to get an alpha plus the spectacularly unstable beryllium-8 which decays into another two alphas? i.e. the triple-alpha process but backwards.

But I think they're more interested in the kinetic energies of the alpha particles than their ionization energies.

https://en.wikipedia.org/wiki/Aneutronic_fusion

Re: Fusion hype

Posted: Tue Feb 25, 2020 11:43 am
by dyqik
You'd get some of both reactions, subject to maybe some selection rules, resonances, and the energetics of the reactions. It may be that the energetics are high enough that even a 12C atom gets smashed.

Calculating the relative cross-sections in the conditions they are proposing is left as an exercise for someone, anyone, else, just so long as it isn't me.