EMC2 has published a polywell preprint on arXiv

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

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D Tibbets
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Re: EMC2 has published a polywell preprint on arXiv

Postby D Tibbets » Mon Jun 09, 2014 6:05 am

The electron thermalization process is of course proceeding. The real question is how fast it is proceeding, Increased density speeds it up, increased machine size increases the oppertunity, and increased temperature slows the process. How all three combine, along with probably several other considerations, determines the answer.

Increased opportunity in larger machines is due to increased transit distance. If confinement is defined in number of transits, then the time to complete a transit is the product of average velocity and distance across the machine. At the same transit confinement number, a 1.5 meter machine would have a confinement time ten times greater than a 0.15 meter machine. Note that average velocity is perhaps tricky, as it is a gradient and also depends how radial from the center the motions are.

The only detailed analysis that I know of is a paper by Bussard. I have referenced it before and it .seemed to satisfy Bussard.

As for thermalization in this machine. The measured x-rays came only from electrons with >2000 eV due to the cutoff filter. As the number of relative low energy ions and electrons from the plasma guns was vastly greater than the ~ 7000 eV e- gun electrons (assume a ~ 1,000,000 to 1 ratio), means the average temperature of the total charged particles did not increase much over the lifetime of the test. The e-gun electrons were the only contributor to the X-rays. That the E-guns were operating before the plasma burst, and the increased plateau values were ~ consistent with the density measurements, it is reasonable to assume that the signal came from increased confinement and thus density of the injected high energy electrons. To work the themalization time had to be longer, perhaps much linger than the confinement time. This places a limitation on the injected electron thermalization time minimum possible. How this would extrapolate to other conditions is complex, but this is at least one example of minimal thermalization time of the electrons under these specific conditions.

The temperature of the injected plasma was presumably somewhere between 1000 and 2000 eV. This is suggested by the quantity introduced and the reported ~ 700 MW of power from the plasma gun. Perhaps about 30 to 40 thousands of plasma amps was injected. Compare this to the e- gun current of ~ 2 amps. Assuming much of the E-guns electrons managed to enter the machine, the electron population would be ~ 10^22 at an energy of ~ 1500 eV, and ~ 10^19 would be ~ 7000 eV (at most). Once mixed and thermalized the average temperature would be ~1510 eV. This is well below the x-ray cutoff filter passage window. So thermalization between the two populations of electrons has to be significantly longer. This is of course an over simplified analysis, but I think serves my argument. It does raise questions about the WB6 situation. The high energy electrons ionized the injected gas and the secondary electrons were heated by the hot electrons. This suggests significant thermalization between the two populations. The conditions are much different between these two machines and requires analysis well beyond my pay scale. That is why I have referred to a detailed analysis. Keep in mind the thermalization has two components. The time it takes for the two populations to near a common average energy, and the time it takes the outliers-mostly up scattered high energy tail, to build to their Maxwellian statistic population. This is a slower process as the higher energy electrons have longer MFP and less frequent Coulomb interactions.

Monoenergetic does not have to imply a very narrow energy distribution. But, I think it does have to imply a significant truncation of the high energy Maxwellian tail. The name is perhaps misleading, but I don't know of any better name.

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

D Tibbets
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Re: EMC2 has published a polywell preprint on arXiv

Postby D Tibbets » Mon Jun 09, 2014 11:13 am

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

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Re: EMC2 has published a polywell preprint on arXiv

Postby ladajo » Mon Jun 09, 2014 12:29 pm

The development of atomic power, though it could confer unimaginable blessings on mankind, is something that is dreaded by the owners of coal mines and oil wells. (Hazlitt)
What I want to do is to look up C. . . . I call him the Forgotten Man. (Sumner)

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Re: EMC2 has published a polywell preprint on arXiv

Postby mvanwink5 » Mon Jun 09, 2014 12:56 pm

I guess Convergent Scientific Inc. just needs to get some gargantuan Godzilla guns and take a look at Beta = 1. Surely they know by now about the news?
Near term, cheap, dark horse fusion hits the air waves, GF - TED, LM - Announcement. The race is on.

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Re: EMC2 has published a polywell preprint on arXiv

Postby dnavas » Mon Jun 09, 2014 1:16 pm


AcesHigh
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Re: EMC2 has published a polywell preprint on arXiv

Postby AcesHigh » Mon Jun 09, 2014 3:53 pm


ladajo
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Re: EMC2 has published a polywell preprint on arXiv

Postby ladajo » Mon Jun 09, 2014 5:58 pm

So basically, he has no real idea on what they have been doing over the last years, and is basing his opinion on prior hearsay.

His wishy-washy wandering critique could apply to any number of initiatives.
The development of atomic power, though it could confer unimaginable blessings on mankind, is something that is dreaded by the owners of coal mines and oil wells. (Hazlitt)

What I want to do is to look up C. . . . I call him the Forgotten Man. (Sumner)

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Re: EMC2 has published a polywell preprint on arXiv

Postby choff » Mon Jun 09, 2014 8:46 pm

Do we know the actual timeframe for the experiments run with this smaller wiffleball machine. The presumption seems to be they went to this after hitting the wall with startup on WB8. It could have been done over any number of the last six years as a side experiment.
CHoff

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Re: EMC2 has published a polywell preprint on arXiv

Postby MSimon » Mon Jun 09, 2014 9:24 pm


D Tibbets
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Re: EMC2 has published a polywell preprint on arXiv

Postby D Tibbets » Tue Jun 10, 2014 3:44 am

The mention of ~7 nanoseconds for the transit time (one pass) in this machine is just wrong, unless I am far off in my understanding. [EDIT- Indeed, I am wrong, see subsequent posts :oops: ] The KE of the electrons of somewhere between 2 and 7 KeV implies speed of eg: 5,000,000 M/s . To travel ~ 15 cm/ 0.15 M requires 0.03 microseconds or 30 nanoseconds for one pass to occur. And, ~ 0.2 microseconds for 7 passes and about 8 microseconds for 300 passes. This is based on a given speed for a 10 KeV electron of 10 million M/s. It also assumes the speed is constant for this average KE and that the path goes through the center on each pass. The average speed of the plasma gun injected electrons and the e-guns injected electrons will vary from this speed but I doubt that it would be more than a factor of two either way, because the velocity only changes as the square root of the energy.

Another number crunching exercise is to consider the injection energy of 7 KeV (for the electrons of intrest) versus 12 KeV in WB6. Assume about a 20 percent drop off from space charge resistance, then the numbers are reduced to ~5.5 KeV and ~ 10 KeV in the compared machines. Assume the average energy is 1/2 of the peak energy. So the KE average energy would be 2.7 KeV and 5 KeV.
The comparative KE is 2.7 / 5 or 0.54. The square root of this is 0,73 or ~0.7. ).7 *10 million M/s gives an average speed of ~7 million M/s in this machine. You can adjust the confinement time accordingly. Do keep in mind though that this a moving target as the confinement passes change and energy loss occurs through radiative processes. Then throw in the degree of thermalization that occurs between the two electron populations and the permutations of the formula becomes very complex. Essentially all of these permutations tends to reduce the energy of the electrons of intrest. On the other side the continuous injection new energetic electrons impedes this decay, but only to the extent that the continous injection keeps up with particle losses.

Dr Parks, etel had to consider all of these factors and design the machine to give the desired/ required conditions for the nessisary makeup of losses (within some brief time limited test interval) to maintain the energetic electron population for long enough and hot enough to give definitive bremsstruhlung output numbers that distinctly showed the difference between regular cusp confinement and Wiffleball/ Beta=1 confinement. That they did so with the budget restraints requiring significant compromises in size and design, is impressive.

PS: Along with the demonstration of the Wiffleball, that they achieved at least a temporary density of well over 10^21 charged particles with this mini machine with modest B fields, goes a long way (I think) towards reaching the densities needed for useful fusion output. If there was some anticipated or unanticipated road blocks to high density operations they were not apparent in this machine.

PS #2: Mmm... Mini B for a name... Not bad. Change it to Mini ME for small machine Magnetic Electrostatic is more catchy and a more obvious plagiarizing of a Hollywood name. 8)

Dan Tibbets
Last edited by D Tibbets on Thu Jun 12, 2014 2:12 am, edited 1 time in total.
To error is human... and I'm very human.

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Re: EMC2 has published a polywell preprint on arXiv

Postby tauntaun_rider » Tue Jun 10, 2014 4:09 pm


dnavas
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Re: EMC2 has published a polywell preprint on arXiv

Postby dnavas » Tue Jun 10, 2014 7:58 pm


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Re: EMC2 has published a polywell preprint on arXiv

Postby mattman » Tue Jun 10, 2014 10:35 pm

Hello,

Dan: Thanks.

The Navy has a great theoretical underpinning for the work:

From the Abstract:

...One way to get around this difficulty is to have no magnetic field in the plasma, so that the radiation becomes only a surface phenomenon instead of a bulk one. Of all the magnetic confining geometries at present known, theoretically only one has enough stability to hold a pure (that is, beta = 8pinkT/B2 = 1) plasma. This is the picket fence or cusped geometry. Unfortunately, according to , the cusps will be very leaky...

is very famous inside the fusion community. Using his paper in Nature as underpinning gives this work credentials. Dr. Tuck devoted a good portion of his career to the "Picket Fence" idea:

Image


Looks like this cusp confinement is making a comeback from the grave
Last edited by mattman on Wed Jun 11, 2014 1:01 am, edited 4 times in total.

mattman
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Re: EMC2 has published a polywell preprint on arXiv

Postby mattman » Wed Jun 11, 2014 12:49 am

I applied the Biot-Savart law to the Navy Device.

My calculations come out about 74% of the field listed in paper.

Not bad.


Image


Anyone see an error with these numbers?

D Tibbets
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Re: EMC2 has published a polywell preprint on arXiv

Postby D Tibbets » Wed Jun 11, 2014 5:30 am

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


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