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Interesting article on FRCs

Posted: Thu Oct 25, 2012 8:45 pm
by Skipjack
I had not seen this article before. It does sound quite encouraging and seems to confirm a lot of John Slough's prior work.
I need more time to read it in full detail though:

Shortened Url

Posted: Thu Oct 25, 2012 8:51 pm
by Skipjack
Here is another article coauthored by Tri Alpha, but it is behind a paywall. The short summary does look very interesting (and encouraging) though:
http://prl.aps.org/abstract/PRL/v108/i25/e255008

Posted: Mon Oct 29, 2012 2:01 am
by Munchausen

Posted: Mon Oct 29, 2012 3:09 am
by Skipjack
Very cool! Great find! Thanks for sharing!

Posted: Mon Oct 29, 2012 5:20 am
by DeltaV
The best part (for engineers):
Our discovery of TWO high energy α-particles is having a huge impact on the reactor design. They are much easier to extract and convert more efficiently into electricity.

Posted: Mon Oct 29, 2012 5:34 pm
by Munchausen
Very cool! Great find! Thanks for sharing!


I cannot say I understand much of it.

Any qualified comments? I guess there is no common agreement that this is the way, the truth and the life.

Otherwise there would be ample resources directed to this.

Posted: Mon Oct 29, 2012 8:07 pm
by choff
The part I picked up on is 'construction of the 100MW reactor is underway.'

Posted: Mon Oct 29, 2012 10:47 pm
by Skipjack
The part I picked up on is 'construction of the 100MW reactor is underway.

Well since this is Tri Alpha and they are fully funded (from what I understand), this is really good news. I have a feeling that this method for nuclear fusion will soon gather a lot more interest.

Posted: Tue Oct 30, 2012 6:14 am
by zapkitty
Skipjack wrote:Well since this is Tri Alpha and they are fully funded (from what I understand), this is really good news. I have a feeling that this method for nuclear fusion will soon gather a lot more interest.


Well, I could be mistaken but I don't think there's anything much
in that article that wasn't already out in the wild.

The only things that stand out to me are the statement about design
changes for the alpha conversion and the overall assertion that T-A
is still going for aneutronic.

... which would scotch certain rumors that T-A had changed
course for neutronic fuels...

edit: ... had any one else heard about that?

Posted: Tue Oct 30, 2012 6:15 am
by choff
Sorry, that was 'design is underway' not construction, but here's hoping.

Posted: Tue Oct 30, 2012 12:04 pm
by Skipjack
well, since this is not ITER, there is hope that the design and construction wont take decades ;)

Posted: Tue Oct 30, 2012 5:55 pm
by D Tibbets
I have wondered howmuch hardware Tri- Alpha has built, as opposed to computer modeling. This shows that they at least have a reactor that is capable of producing a few measurable P-B11 fusion events.

The resance peak at ~ 600 KeV is consistant with published cross sections=

http://iec.neep.wisc.edu/operation.php

The information is confusing about the energy of the two alphas from the excited Beryllium 8, and the C12 breakdown that also produces one of the alphas is barely mentioned except for one graphic, which is interesting as it seems to show the third alpha as having lower energy (?).

The point of only a few energy ranges needing to be accommodated reenforces what has already been stressed for direct conversion. Compared to D-D fusion with outcomes of a high energy pr oton, tritium, He3 at different energies is more challenging to convert,and this at most accounts for ~ 50% of the aviable energy- the rest is carried by a neutron).

The target of 600 KeV for center of mass energies to produce the most fusion, may not reflect the best target. Since this is a peak, it means the cross section is leveling off, which means little gain in this area. The Bremsstruhlung radiation continues to rise exponentially, so actual gain may be negative. This may be reflected by Bussard's target of ~ 400 KeV center of mass kinetic energy target. It is on the steep up slope of the fusion cross section curve, and the Bremsstruhlung is less (perhaps ~ 40% as much. There is some sweet spot where the two competing effects has the most beneficial solution.

I, of course, hope that the plasma thermalization can be controlled to such an extent that the resonance peak at ~ 120 KeV can be used. Almost as much fusion (fusion numbers multiplied by the difference between the fuel KE, and the fusion products KE) and only ~ 10% as much Bremsstruhlung.

As a side point, This Bremsstruhlung vs the fusion cross section slope is why ideas of pushing D-D fusion up to ~ 1 MeV is counter productive. The fusion cross section slope is increasing , but at a shallow angle, while the Bremsstruhlung continues to also increase at an exponential rate (~T^1.75). There is also a sweat spot for this reaction, which according to Bussard seems to be at ~ 80-100 KeV.
Note that the MFP at the working densities and energies and machine radius is also an important considerations if annealing is considered in The Polywell.

Dan Tibbets

Posted: Tue Nov 13, 2012 9:21 pm
by Munchausen
Are those numbers of any significance?

The FRC confinement times are improved by factors 2 to 4, and the plasma lifetimes are extended from 1 to up to 4 ms.