Bussard and Jamesson list some aneutronic fuel combos…

[zapkitty]

“Inertial Electrostatic Fusion Propulsion Spectrum: Air-Breathing to Interstellar Flight” Robert W. Bussard and Lorin W. Jamesson, 1993, Journal of Propulsion and Power, Vol. 11, No. 2, pp. 365-372. (minor updates, December 2008)

H(p) and 11B
6Li/7Li and 9Be
3He and 3He
3He and D

[Ivy Matt]

After reading the article I’m not certain if they meant Li6/Li7+Be9, or if they meant p+Li6/Li7 and p+Be9. I kind of think it’s the latter. I’m not familiar with any fusion reaction involving Be9 as an input, but I am somewhat familiar with the p+Li6 and p+Li7 reactions. The former produces a He4 ion at 1.7 MeV and a He3 ion at 2.3 MeV, for a total of 4 MeV. The latter produces two He4 ions at a total of 17.2 MeV. Lately I’ve been wondering why p+B11 is seen as the “Holy Grail” of aneutronic fusion, and p+Li7 isn’t. There aren’t any downsides to p+Li7 as far as I can tell, and it should be easier for most confinement concepts to achieve.

[zapkitty]

Ivy Matt wrote: After reading the article I’m not certain if they meant Li6/Li7+Be9, or if they meant p+Li6/Li7 and p+Be9. I kind of think it’s the latter. I’m not familiar with any fusion reaction involving Be9 as an input, but I am somewhat familiar with the p+Li6 and p+Li7 reactions. The former produces a He4 ion at 1.7 MeV and a He3 ion at 2.3 MeV, for a total of 4 MeV. The latter produces two He4 ions at a total of 17.2 MeV. Lately I’ve been wondering why p+B11 is seen as the “Holy Grail” of aneutronic fusion, and p+Li7 isn’t. There aren’t any downsides to p+Li7 as far as I can tell, and it should be easier for most confinement concepts to achieve.

Well, I’d squirreled that paper away for ideas and references (along with a lot of others) but had not paid attention to their aneutronic fuel list until I began reviewing my spaceplane assumptions. Then the “Be” registered… 🙂

I wonder what lithium compounds might be suitable, if any…

[NoSmoke]

Ivy Matt wrote: After reading the article I’m not certain if they meant Li6/Li7+Be9, or if they meant p+Li6/Li7 and p+Be9. I kind of think it’s the latter. I’m not familiar with any fusion reaction involving Be9 as an input, but I am somewhat familiar with the p+Li6 and p+Li7 reactions. The former produces a He4 ion at 1.7 MeV and a He3 ion at 2.3 MeV, for a total of 4 MeV. The latter produces two He4 ions at a total of 17.2 MeV. Lately I’ve been wondering why p+B11 is seen as the “Holy Grail” of aneutronic fusion, and p+Li7 isn’t. There aren’t any downsides to p+Li7 as far as I can tell, and it should be easier for most confinement concepts to achieve.

Wiki has some info on that:

“Some reaction candidates can be eliminated at once. The D-6Li reaction has no advantage compared to p-11B because it is roughly as difficult to burn but produces substantially more neutrons through D-D side reactions.

There is also a p-7Li reaction, but the cross section is far too low, except possibly when Ti > 1 MeV, but at such high temperatures an endothermic, direct neutron-producing reaction also becomes very significant.

Finally there is also a p-9Be reaction, which is not only difficult to burn, but 9Be can be easily induced to split into two alpha particles and a neutron.”

http://en.wikipedia.org/wiki/Nuclear_fusion

[Ivy Matt]

The page on aneutronic fusion also mentions the low cross section of p+Li7 but, even though I check it from time to time for the list of fusion reactions, it’s been a while since I read it all the way through. Okay, boron it is, then.

However, I did look up lithium and its compounds. If lithium-7 were to be introduced into a DPF device the way LPP intends to introduce decaborane, lithium hydride (LiH) would be the obvious choice. However, it has a very high melting point and it reacts explosively with water. Sounds like decaborane is a better choice. And, if you don’t mind mixing reactions, there’s also lithium borohydride. Of course, if p+B11 has a better cross section, there’s no point in doing that.

[malaga2022]

I thing there are two possible aneutronic reactions:

Li+P reaction: http://img192.imageshack.us/img192/1918/pli6.jpg
And 11B+P reaction: http://img69.imageshack.us/img69/135/p11bu.jpg

As can be seen in the link:
6Li+P reaction cross section is only 0.25 barns at 2MeV and remains over 0.1 barns in the 0.7-4.5MeV range
11B+P reaction cross section goes up to 0.8 barns at 0.6MeV and remains over 0.1 barns in the 0.35-3MeV range (then gets neutronic through 11B+P->6C+N reaction)

The only problem for 6LiH is that it is impossible to buy it. Is easier buy 6LiD at 127$/10gr. It does not exists CAS number for it.
Anybody knows where to buy it? I would need 5 grams only.

Attached files

[jamesr]

Nice graphs.

Although at the temperatures achievable in any practical device only cross-section below 500keV incident energy is important. In particular for p-B11 it is the small resonance spike at 148keV that helps boost the overall reaction rate in the 10-100keV temperature range.

If you take these cross-section vs incident energy curves and average over a Maxwellian velocity distribution you get the more meaningful reaction-rate vs temperature graph.

Here is one from Wesson’s Tokamaks book which shows pB11 in comparison to DT DD etc, but doesn’t show all the Lithium reactions

Attached files

[malaga2022]

I have seen the peak in the 550-750 keV range. It was used experimental data from Exfor database extracted from here:
http://www.sciencedirect.com/science/article/pii/037594747990647X

Does plasma at focus fusion device fits Maxwell distribution under huge magnetic fields and extreme short pulse? I thought different speed for e, Li/B and P and helical non convergent movement

Attached files

[malaga2022]

It exists another aneutronics: Lithium-6 borohydride: 6LiBH4, it is a metal with low melting point.

[Author]

Posts