Lawrenceville plasma physics June update

Point out news stories, on the net or in mainstream media, related to polywell fusion.

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nextbigfuture
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Lawrenceville plasma physics June update

Post by nextbigfuture »

at my site- summarized two new focus fusion.org updates. LPP believes they are on pace to prove scientific feasibilty (I think energy breakeven for each shot) by the end of this year


http://nextbigfuture.com/2010/06/lawren ... gress.html

Skipjack
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Post by Skipjack »

I cant believe it, but I think I beat you to it, this time, gggg

viewtopic.php?t=2311

kcdodd
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Post by kcdodd »

Is it just my math or are they 4 orders of magnitude away from their goal.
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D Tibbets
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Post by D Tibbets »

kcdodd wrote:Is it just my math or are they 4 orders of magnitude away from their goal.
That is what it looks like to me, though comparing amps to neutrons may not be the whole story. What about volts? My BOE number I use for fusion of D-D is that ~ 1 trillion fusions yields one watt of power.

Looking at the graph- the single red and two green data points seems to form a straight line, extending the graph should reach breakeven at ~ 1.2 million amps, if the rate does not tail off. As DPF is predicted to only reach Q's of ~ 2 there will be significant tailing off / leveling of the yield at some point presumably near 1-2 or 1.3 million amps(?).

Dan Tibbets
To error is human... and I'm very human.

kcdodd
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Post by kcdodd »

I am just going on what they said they need to show feasibility: 10,000 - 100,000 Joules. They say they are at around 1e11 neutrons per shot. Giving 20MeV per neutron (accounting for any aneutronic contribution) that gives 0.3 Joules.
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nextbigfuture
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back in April they were calculating 0.5-1 kilojoules

Post by nextbigfuture »

http://www.lawrencevilleplasmaphysics.c ... &Itemid=90

0.5 kilojoules in the beams and 1 kilojoule in the plasmoid

Munchausen
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Re: back in April they were calculating 0.5-1 kilojoules

Post by Munchausen »

nextbigfuture wrote:http://www.lawrencevilleplasmaphysics.c ... &Itemid=90

0.5 kilojoules in the beams and 1 kilojoule in the plasmoid
I sincerely doubt they have Q=2

kcdodd
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Re: back in April they were calculating 0.5-1 kilojoules

Post by kcdodd »

nextbigfuture wrote: http://www.lawrencevilleplasmaphysics.c ... &Itemid=90

0.5 kilojoules in the beams and 1 kilojoule in the plasmoid
What is the significance of those numbers?
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D Tibbets
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Re: back in April they were calculating 0.5-1 kilojoules

Post by D Tibbets »

kcdodd wrote:
nextbigfuture wrote:http://www.lawrencevilleplasmaphysics.c ... &Itemid=90

0.5 kilojoules in the beams and 1 kilojoule in the plasmoid
What is the significance of those numbers?
Actually 0.5 KJ in the beams and 1KJ in the plasmoid would represent up to 0.5 Q, depending on other considerations. How many joules go into creating the plasmoid? How much of the beam current consists of fusion ions, and how much is unburned fuel ions? Assuming some arbitrary efficiency for these two parameters of 50% would, I think, result in a Q of ~ 0.12. I'll guess that the electrode joules to plasmoid joules conversion may be fairly efficient,and that the efficiency (percentage) of deuterium ions in the plasmoid that fuse is currently small.
Will the increased feed current increase the plasmoid temperature, it's containment time, and/ or it's density?
Does anyone know of a graph of the expected Q vs the plasmoid energy? Does it level off and thus limit the possible gain? Or, is it more dependent on expectations of what input energies are obtainable from an engineering perspective?

Dan Tibbets
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kcdodd
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Post by kcdodd »

How do you get Q of 0.5? How are you calculating fusion output?
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D Tibbets
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Post by D Tibbets »

kcdodd wrote:How do you get Q of 0.5? How are you calculating fusion output?
I'm assuming that the Joules in the beams consist of ions- either deuterium ions as that is the gas in the system at startup, and/ or fusion ions- protons, tritium or He3. The proportions of these ions would indicate the efficiency of the fusion reaction. Actually, I am ignoring neutrons, so if the beam energy is all fusion product ions, then the Q would be close to one, as the neutrons are contributing ~ 1/2 of the output power in this reaction. Also, I don't know if there are any secondary reactions with the produced tritium and He3.
I'm also ignoring the energy contribution or loss from the electron beam that is exiting the plasmoid in the opposite direction of the ion beam.

Dan Tibbets
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kcdodd
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Post by kcdodd »

I don't think beam energy is coming from fusion. They say "a substantial part of the total energy available is being concentrated in the plasmoids and transferred to the beams".
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D Tibbets
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Post by D Tibbets »

kcdodd wrote:I don't think beam energy is coming from fusion. They say "a substantial part of the total energy available is being concentrated in the plasmoids and transferred to the beams".
Some is coming from fusion, otherwise they would not be getting neutrons. The deuterium gas present in the machine is trapped and compressed by the plasmoid formation. To know the proportion of fusion ions, compared to non fused deuterium ions, you need to know the amount of deuterium trapped in the collapsing plasmoid. The DPF site described that they obtained a plasmoid with unexpectedly high background gas density. I'm guessing that this might be considered as an unexpected advantage, or not, depending on how it effects other concerns. That, and their reported better fusion rate vs input Joules, compared to most studies (if real) should reinforce their optimism that they will reach their goals.

Dan Tibbets
To error is human... and I'm very human.

Torulf2
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Post by Torulf2 »

There are two kinds of output energy, the beam and x-rays.
There are two kinds of input energy, the original current and resulting fusion.
I think the energy in the beams mainly come from the input current.
Is there any mechanism for the fusion generated energy to go into the beams?
Else the fusion energy would go thermal and then in to x-rays.

D Tibbets
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Post by D Tibbets »

Torulf2 wrote:There are two kinds of output energy, the beam and x-rays.
There are two kinds of input energy, the original current and resulting fusion.
I think the energy in the beams mainly come from the input current.
Is there any mechanism for the fusion generated energy to go into the beams?
Else the fusion energy would go thermal and then in to x-rays.
The energy in the beams (at least the ion beam) consists of charged ions traveling at high speeds. In that sense a fusion produced ion is part of the input energy for the beams, but if you are considering the input and output energies of the machine overall, the fusion ions are definitely output energy (at least if they come from exothermic nuclear reactions). I don't know the speed / energy of the unburned deuterium ions in the beams. If it is anywhere near the speed of the fusion ions, I do not believe there could be any net gain. They have mentioned obtaining 10s of thousands of eV energy into the plasmoid (heating the deuterons to those energies). Any fusion ions produced (P, tritium, or He3) have speeds of ~ 1 MeV or more, definitely an output gain. As mentioned, I don't know if these fusion products hang around long enough to contribute to more fusion or heating like in ignition machines (tokamaks). That effect could be considered as in situ input energy (from the beams perspective).
The D-D fusion also produce neutrons which represent output in the form of heat. The X-rays, I believe, comes from Bremstrulung, so could be considered as waste, or as a contributor to further heating the fusion plasma as x-rays do in hydrogen bombs. But, I beleive this requires reflecting/ absorbing the the x-rays in the core of the machine, something that would further erode the electrodes in the DPF. And, they are trying to minimize this. If P-B11 is used, the x-rays carry away so much of the plasmoid energy that they cannot breakeven- unless they manage to recapture most of this energy through direct conversion.
On the surface, the DPF would seem to be more suited to D-D or D-T fusion, but I assume the neutrons produced in these reactions destroy the electrodes even faster than the x-rays do in the P-B11 reaction.
For research, or as a consumable intense neutron or X-ray source, a D-D or D-T DPF seems reasonable, and a lot cheaper than something like the NIF laser approach. I think it might also be cheaper, or at least smaller, than a Z- pinch machine.

Dan Tibbets
To error is human... and I'm very human.

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