About March 2013 report

[asymmetric_implosion]

Vlad: You need to be a bit careful using temperature and ion energy seemingly interchangeably. Temperature is key in thermal fusion devices. In principle, you can have a cold plasma that produces neutrons very well in a pinch. Pinch devices exploit the instabilities to produce non-thermal ions, ions that don’t conform to a thermal distribution. It is of these ions that efficiently produce neutrons. Small PF devices which have temperatures of less than 1 keV can produce neutrons well beyond the expectations of thermal calculations. LPP hypothesizes that their configuration to place a lower limit on the ion energies. If the LPP approach works, energies below 200 keV would not be relevant to the problem. It’s not clear how far the lower limit can be pushed up but the higher the better for p+11B.

As far as the “honest” calculation goes, a great deal of engineering is required to prove that the energy from RLC ring can be recycled. I’ve looked into using energy recovery technology for a small PF device in the past. State of the art technology was nearly enough to work at the 60 kA level. At 3 MA, it seems unlikely with current materials.

Francisl: The MAGLIF concept implodes a pre-magnetized, 100 eV plasma into a pinch. The initial magnetic field is flux compressed limiting the heat transfer of electrons and partly trapping alpha particles. The approach relies heavily on a thermal DT plasma. The density and magnetic field should suppress fast ions that the LPP approach relies on.

[vlad]

asymmetric_implosion wrote: Vlad: You need to be a bit careful using temperature and ion energy seemingly interchangeably. Temperature is key in thermal fusion devices. In principle, you can have a cold plasma that produces neutrons very well in a pinch. Pinch devices exploit the instabilities to produce non-thermal ions, ions that don’t conform to a thermal distribution. It is of these ions that efficiently produce neutrons. Small PF devices which have temperatures of less than 1 keV can produce neutrons well beyond the expectations of thermal calculations. LPP hypothesizes that their configuration to place a lower limit on the ion energies. If the LPP approach works, energies below 200 keV would not be relevant to the problem. It’s not clear how far the lower limit can be pushed up but the higher the better for p+11B.

you mean that the graph you posted above shows not ion energy, but thermodynamic temperature of thermalized plasma? OK

asymmetric_implosion wrote: As far as the “honest” calculation goes, a great deal of engineering is required to prove that the energy from RLC ring can be recycled.

yes, I see
engineering is much worse than clean pure physics 🙂

Thank you for your explanations!

[asymmetric_implosion]

The graph is ion energy.

[JimmyT]

If you want to stick with aneutronic fusion (a good idea in my opinion) the options are pretty well summarized in this Wiki article: http://en.wiki.org/wiki/Aneutronic_fusion

If you look at just at the amounts of energy released you would think that Lithium 6 or 7 would be the preferred fuel.

Lithium 6 + Deuterium yields 22.4 Mev

Lithium 7 + Proton yields 17.2 Mev

Boron 11 + Proton yields 8.7 Mev

But Lithium has a very low cross sections, and thus would require higher confinement time to get comparative yields to boron.

Still, before the dust settles, maybe it would be interesting to try.

The Wiki article contains a link to The Focus Fusion Society BTW.

I think these alternate fuels may have been discussed in prior posts a couple of years ago.

It’s also worth noting that Eric fudges his calculations:

He notes increased linear compression of a factor of 4 which yields increased density of a factor of 20. Four cubed is 32 (64)
not 20. He also claims that doubling the current will increase yield by a factor of 20. But this process has reliably scaled to the 5th power. Two to the fifth power is 32 Not 20.

Overall this is good news, as his projections thus have a relatively large “fudge factor” which can be used to decrease the input current, increasing the net output. Or perhaps decreasing the pulse frequency, thereby making heat removal a bit easier to deal with. Or some combination of the two.

[zapkitty]

… margins are good 🙂

[Henning]

JimmyT wrote:
He notes increased linear compression of a factor of 4 which yields increased density of a factor of 20. Four cubed is 32 not 20. He also claims that doubling the current will increase yield by a factor of 20. But this process has reliably scaled to the 5th power. Two to the fifth power is 32 Not 20.

Well, the current scaling is somewhat to the 4.7th power for a few experiments. So 20 is more accurate here. Don’t overpromise.

[Brian H]

Henning wrote:

He notes increased linear compression of a factor of 4 which yields increased density of a factor of 20. Four cubed is 32 not 20. He also claims that doubling the current will increase yield by a factor of 20. But this process has reliably scaled to the 5th power. Two to the fifth power is 32 Not 20.

Well, the current scaling is somewhat to the 4.7th power for a few experiments. So 20 is more accurate here. Don’t overpromise.

26, exactly halfway inbetween.

[Author]

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