Lawaranceville E-Newsletter

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

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Torulf2
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Re: Lawaranceville E-Newsletter

Postby Torulf2 » Wed Sep 24, 2014 4:39 pm

The use of Be may not make the reaktor more toxic.
They already have to be careful with the boron hydrides used.

D Tibbets
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Re: Lawaranceville E-Newsletter

Postby D Tibbets » Wed Sep 24, 2014 8:45 pm

The boron compounds are toxic, but they have not yet been used, though admittedly, they have claimed they wish to pursue this eventually, perhaps sooner than later. One point is that boron hydrides are toxic but can be easily destroyed by burning the chamber exaust in a methane flame, or perhaps just a heated air flow. The boron element is toxic though, which means it has to be sequestered, not just converted. Or, perhaps just diluted enough so that the exhaust is below EPA emmision standards for boron.

Burning boron in a reactor involves purifying the B11 isotope, so boron 10 is not an issue. There may be uses for purified boron 10 though such as in the discription by Bussard and others to supplement the output of a D-D reactor. I think it is called the D-D one half catalyzed reactor. The neutron from D-D reactions is captured by an external blanket of B10 and the subsequent breakdown to tritium and finally He3 (if you want to wait and you want a supply of He3 for a relatively aneutroniuc reactor for a ship, etc.) provides additional fuel that can be mixed in to increase final yield, as is the tritium and He3 produced directly from the D-D reaction branches.

Various nuclear reactions with various isotopes of beryllium, along with many other elements can give interesting, problematic and/ or energy yielding results. But, the rate of these reactions are trivial except for possibly radioactive dacay concerns. The contributions to energy yield is negligible. The cross section curves are very much smaller than the P-B11 reactions and thus the reaction rates are correspondingly tiny.
Also, keep in mind that any ion with a Z greater than one is harmful to the energy balance due to bremsstruhlung issues. You have to have B11, but any other elements in the plasma other than hydrogen are contaminates- poisons (in the sense that they cool the plasma). The excited beryllium that is created by the excited C12 isotope that is created by P-B11 fusion has an extreamly short half life before it breaks down into two alphas. It is around for such a short time it does not have a significant chance to participate in the bremmstruhlung producing collisions. The alphas probably produce more bremmstruhlung producing collisions with electrons, but fortunately the alphas also don't hang around long as they exit the reactor relatively fast compared to the fuel P and B11 ions.

PS: The handling of boron may not involve difficult sequestering or dillution schemes, but just as with tritium, you have to have the monitoring, ' licencing' infrastructure in place. This can be very expensive by itself. Even Tokamaks which are strictly D-T dependent reactors for potential breakeven often use D- D fuel because it is much simpler and cheaper. The extrapolation to D-T results can then be calculated with fair usefulness. The Japanese Tokamak pursued this path.
In a lab with a billion doller per year budget the additional costs are easily managed (perhaps a few million dollers per year). But with a budget of less than a million dollers per year the additional cost is intolerable.

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

Ivy Matt
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Re: Lawaranceville E-Newsletter

Postby Ivy Matt » Sat Oct 25, 2014 6:08 am

Temperature, density, confinement time: pick any two.

DeltaV
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Re: Lawaranceville E-Newsletter

Postby DeltaV » Sat Oct 25, 2014 4:58 pm


Ivy Matt
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Re: Lawaranceville E-Newsletter

Postby Ivy Matt » Tue Oct 28, 2014 12:36 am

Temperature, density, confinement time: pick any two.

Ivy Matt
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Re: Lawaranceville E-Newsletter

Postby Ivy Matt » Thu Nov 20, 2014 7:27 am

Temperature, density, confinement time: pick any two.

Ivy Matt
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Re: Lawaranceville E-Newsletter

Postby Ivy Matt » Fri Dec 26, 2014 5:41 pm

Temperature, density, confinement time: pick any two.

Ivy Matt
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Re: Lawaranceville E-Newsletter

Postby Ivy Matt » Wed Jan 28, 2015 5:03 am

LPPFusion has released their . It contains a retrospective of 2014: what was accomplished (publication, fundraising, hiring staff, website redesign, release of processed data) and what wasn't (delivery of tungsten cathode, actual experimental shots), and a plan for 2015:

Q1: Complete computer and data base upgrade, install and begin testing new tungsten cathode. Density and fusion yield are expected to increase 100-fold. LPPFusion will also experiment the effects of mixing in heavier fill gases, such as nitrogen.
Q2: Move to shorter electrodes, which is expected to increase fusion yield further.
Q3: Bring current up to 2MA, increasing density and fusion yield further still.
Q4: Install beryllium electrodes, or at least a beryllium anode. Demonstrate density of over 1 gram/cc and billion-Gauss magnetic fields. Install new equipment and begin running with hydrogen-boron fuel.

Last I heard the tungsten cathode was being machined in China. I haven't heard that it's finished. Also, in the report LPPFusion mentioned they are planning a backup monolithic copper cathode.
Temperature, density, confinement time: pick any two.

RERT
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Re: Lawaranceville E-Newsletter

Postby RERT » Wed Jan 28, 2015 1:25 pm

Can anyone shed light on where they will be if they meet this schedule?

Fumbling with Wikipedia suggests that their triple-product must be very interesting with even micro-second confinement times at 1 gram/cc.

To say I'm uncertain about this is a massive understatement, so wiser comment appreciated!

Another comment would be that the engineering part of their schedule looks pretty simple to the man in the street, except maybe the current uplift.

Let's hope the physics behaves...

D Tibbets
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Re: Lawaranceville E-Newsletter

Postby D Tibbets » Wed Jan 28, 2015 7:42 pm

Triple product comparisons are straight forward. Varying only density (fusion can scale as the square of the density), then if a Tokamak at 10^ 19 or 10^20 particles / M^3 requires ~ 1000 seconds confinement time, then ~100 milliseconds in a Polywell at 10^22 density gives similar results, and 100 nano seconds in a DPF at a density of 10^25 also gives similar results. This is still a density well below 1 g/cc. I don't recall the precise timeline in a DPF, but I think the plasmoid forms over a few hundred nanoseconds to a few microseconds, and the fusion action occurs primarily over a few 10s of nanoseconds, which brings the comparison closer to densities of ~ 10^27 particles per cubic meter, or ~ 1 g/cc (for hydrogen isotopes). Note that this time frame is similar to atomic/ hydrogen bombs with interesting timelines in nanoseconds and which have similar particle densities.

I may be pointing out the obvious, but I have repeatedly seen misconceptions on this forum, where confinement time comparisons of Tokamaks and Polywells are implied to indicate the dismal performance of the Polywell. Comparisons, though, require the inclusion of the exponential effects of density . A density increase of 100 X results in a fusion rate 10,000 X greater with corresponding decreases in required confinement time.

In the past this comparison has been couched in the required distance the particles have to travel before a likely collision will occur. A few hundred thousand kilometers in a Tokamak is comparable to a few tens of Kilometers in a Polywell once the density contribution to the triple product is factored in. The ratios remain the same.

Note that things become more messy when D-T reactions are compared to D-D or P-B11 fuels,and machine temperature considerations and thremalization contributions are considered; and additional factors may also apply such a POPS, density gradients, central confluence/ focus, etc. But the basic ratios of time to density remain a simple comparison between the various approaches.

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

Ivy Matt
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Re: Lawaranceville E-Newsletter

Postby Ivy Matt » Tue Mar 03, 2015 8:34 am

Temperature, density, confinement time: pick any two.

D Tibbets
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Re: Lawaranceville E-Newsletter

Postby D Tibbets » Mon Apr 20, 2015 5:05 am

The work continues in efforts to get the tungsten cathode operational, or alternate discription- the fun of engineering...

http://lawrencevilleplasmaphysics.com/t ... s-forward/

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

Maui
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Re: Lawaranceville E-Newsletter

Postby Maui » Mon Apr 20, 2015 5:31 am


RERT
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Re: Lawaranceville E-Newsletter

Postby RERT » Mon Apr 20, 2015 1:06 pm

With that number of people, refering to e.g. 'the engineering department' would be kind of disingenuous... R.

Ivy Matt
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Re: Lawaranceville E-Newsletter

Postby Ivy Matt » Tue Apr 28, 2015 3:52 am

Temperature, density, confinement time: pick any two.


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