Recovery.Gov Project Tracker

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

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ltgbrown
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Postby ltgbrown » Wed Feb 02, 2011 6:20 pm

The reason I think it most likely someone knows is that if I were them, I would have a neutron count in my mind that roughly equates to "that proves the scaling laws." Yes, they will have to go through a lot of analysis, peer review and multiple runs and yes that takes time. But to think that 2, approaching 3, months after achieving first fusion they haven't seen enough neutron counts to have an idea if the thing works or not is at least very pessimistic, likely degrading (of their abilities), and maybe naive.

But then again, I only slept at a Holiday Inn Express. :P
Famous last words, "Hey, watch this!"

WillKell
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Postby WillKell » Wed Feb 02, 2011 6:29 pm

How about a Recovery.gov link?

I am having trouble finding it!

Thanks

Enginerd
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Postby Enginerd » Wed Feb 02, 2011 6:56 pm

WillKell wrote:How about a Recovery.gov link?

I am having trouble finding it!

Thanks


http://www.recovery.gov/Transparency/Re ... =Contracts

Roger
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Postby Roger » Wed Feb 02, 2011 7:01 pm

I like the p-B11 resonance peak at 50 KV acceleration. In2 years we'll know.

KitemanSA
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Postby KitemanSA » Wed Feb 02, 2011 7:44 pm

ltgbrown wrote:The reason I think it most likely someone knows is that if I were them, I would have a neutron count in my mind that roughly equates to "that proves the scaling laws." Yes, they will have to go through a lot of analysis, peer review and multiple runs and yes that takes time. But to think that 2, approaching 3, months after achieving first fusion ....
The report states "First Plasma", not "First Fusion". We have had NO reports of fusion yet. 8o :roll:

ltgbrown
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Postby ltgbrown » Thu Feb 03, 2011 6:36 pm

The report states "First Plasma", not "First Fusion". We have had NO reports of fusion yet. 8o


Concur. But (I think that is my favorite word!) don't you think it likely, terribly likely, that they have at least tried to achieve fusion since November? And if they tried, that they had a number (neutron count) in mind that if they see then they are on to something? That is what I am trying to say. Just how many times do the need to "achieve plasma" before trying to achieve fusion? I understand the need to tweak the instruments and computer controls and what not, but if they have put enough power into it to achieve plasma, just how much more (power, ions, whatever) is needed in order to achieve fusion? Not maximum rate of fusion, just some. For x amount of power, and y and z amounts of electrons and ions, we should see (assuming our theories and math are correct) h (for happy) number of neutrons representing f rate of fusion which means ... Get my point.

Another thought is that if they had put "first fusion", that might have gotten them a lot more interest than they wanted, as some have argued they are trying to avoid.
Famous last words, "Hey, watch this!"

D Tibbets
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Postby D Tibbets » Thu Feb 03, 2011 8:03 pm

A careful comparison between WB 7 work and WB 8 work gives some indication of the relative timeliness.
Wb7 was a non cooled machine. If similar to WB6 they may have been able to run only several tests per day, as the cool down time between tests may have been multiple hours. They had first plasma in Jan. and were ready to present their results to the review committee in August, an interval of ~ 7 months. With WB8, they have more staff and the benefit of previous experience. Conversely the machine is larger, and that may tend to slow things down. The major difference though may be the cooling. This may allow them to run dozens of tests per day versus a couple. This could promote much faster data collection. . Other variables include the range of test conditions they are pursuing, how often they need to open the system, equipment reliability, length of lunch breaks, paperwork load, back seat drivers, sense of urgency, holidays, breaks, etc, etc...

In conclusion, the development and testing time for this generation of the Polywell (once first plasma is reached) may take a few months less than WB7 to several years more than WB7. :roll:

I suspect their original schedule was to obtain first plasma quicker than November, 2010, but that is speculation. This may mean their schedule has slipped a few months.
Conversely, the number of tests under various conditions may not need to be much in order to develop a strong confidence in the scaling laws. The neutron output (if that is the critical measure) should be profuse enough that statistically significant results, should be much easier to acquire. The trends should be glaring, not nuanced.
This, along with possibly more frequent test runs, would allow presentation and review to proceed quickly, while optimizations, and data set expansion was ongoing.

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

Enginerd
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Postby Enginerd » Thu Feb 03, 2011 8:49 pm

D Tibbets wrote:The neutron output (if that is the critical measure) should be profuse enough that statistically significant results, should be much easier to acquire.


If this thing is (as we hope) spitting out neutrons by the truckload, I wonder if they have installed something like a big lead and plastic lined water tank surrounding the WB-8 for radiation shielding?

D Tibbets
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Postby D Tibbets » Thu Feb 03, 2011 9:09 pm

Enginerd wrote:
D Tibbets wrote:The neutron output (if that is the critical measure) should be profuse enough that statistically significant results, should be much easier to acquire.


If this thing is (as we hope) spitting out neutrons by the truckload, I wonder if they have installed something like a big lead and plastic lined water tank surrounding the WB-8 for radiation shielding?


Yes and no- Compared to WB6, the neutron output may be several thousand times greater. But, remember, the neutron output is reported as neutrons per second. WB 6 was about ~ 500,000,000 neutrons per second, but as the machine ran for only ~ 0.25 milliseconds, the total neutron output was ~ 100,000 neutrons per test. Compare this with a good amateur fusor, that might be putting out ~ 1,000,000 neutrons per second and run for several minutes. Your exposure would be very much higher if you hung around the amateur furor. The final exposure depends on the number of tests, the duration of each test, the distance from the reactor and of course the shielding.*

Actual radiation exposure dangers in these machines is actually in the form of X-rays. Without working the numbers, I suspect you would still need to increase the neutron (fusion) output by several orders of magnitude before it caught up to the danger from the X-rays. If you pay attention to the X-ray safety concerns, you are covered for neutrons. Once neutron outputs become high enough, the shielding picture changes as you have to consider water or some other light element containing compound to moderate the neutrons so that they can be absorbed (stopped) by subsequent shielding that doubles as X-ray shielding.

*If the run times for WB8 are reaching 10's of milliseconds, the neutron exposure per test would be multiplied further (as would the X-rays).

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

icarus
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Postby icarus » Fri Feb 04, 2011 12:28 am

Neutron shielding eh?

I think the last verified count was that Polywell had produced 3 or 4 neutrons.

Ha, neutron shielding could be the last of their problems.

D Tibbets
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Postby D Tibbets » Fri Feb 04, 2011 1:30 am

icarus wrote:Neutron shielding eh?

I think the last verified count was that Polywell had produced 3 or 4 neutrons.

Ha, neutron shielding could be the last of their problems.


That is an entirely misleading statement. 3-4 neutrons were detected by WB6- at least that is the claim. Surely you realize what this means?
Many electronic neutron detectors actually detect, or measure ~ 1 neutron out of several thousand that actually hits it. The neutron source is isotropic. That means it emits neutrons in all directions equally. So, when a detector is placed on a sphere a certain distance from the source, it will be hit by that (small) fraction of neutrons that are traveling through that fractional surface area covered by the detector.
That, multiplied by the sensitivity of the detector (eg: 1/4000 neutrons detected), then adjusted for the distance from the source, and the time interval gives the actual neutrons produced. That is where the 500,000,000 neutrons per second comes from.

You can argue about signal to noise ratios and the accuracy based on such few actual detections, proper calibration of the instruments, etc. but you cannot argue about the subsequent conversions to determine the isotropic neutron output per unit of time. Nor can you argue about how this relates to other fusion machines (within the limits of the test parameters- voltage, density, B-field strength, geometry,etc). You can argue about what happens when these parameters change, thus the purpose of WB8 and in part WB7.

Hear say is that the statistics for three counts, means there is a uncertainty range (standard deviation?) of ~ 1/3, or the actual neutron count may have been 3 +/- 1.
An increase (or decrease) of 50% in the fusion rate in WB7 compared to WB6 would only barely be detectable statistically. That leaves a considerable amount of uncertainty about the results, and subsequent scaling. Neutron detections of 100's or thousands within the test time, changes these statistics considerably. The precision and detectable change limits are both vastly improved.

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

TallDave
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Postby TallDave » Fri Feb 11, 2011 9:24 pm

Valenacia says fusion was produced and detected by several WB machines.

If WB-8 is producing the expected 8-64W (I forget exactly where Dan and I and others ended up agreeing/disagreeing the expected range was) then the question is over what time period. Despite the presence of the LN tanks I strongly suspect WB-8 is not steady-state because the WB-6 sweep only reached optimal beta = 1 condtions for a quarter-millisecond and I'm doubtful they have all the PID stuff set up to keep it there.

My guess is they won't be sweeping through beta=1 slow enough to have more than a tenth of a second of fusion (meaning radiation risk is minimal) but I'd be curious what others think.
n*kBolt*Te = B**2/(2*mu0) and B^.25 loss scaling? Or not so much? Hopefully we'll know soon...

KitemanSA
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Postby KitemanSA » Sat Feb 12, 2011 2:29 am

Given Bfield is 8X and size is 2X...
Power(WB8) = b^4*r^3*Power(WB6) ~ 8^4*2^3*0.6mW~20W.

http://www.ohiovr.com/polywell-faq/inde ... reactor%3F

ladajo
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Postby ladajo » Sat Feb 12, 2011 5:01 am

Aren't the WB8 coil diameters(radii) the same as WB7/WB6?
I thought they only are jacking up the field?

Betruger
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Postby Betruger » Sat Feb 12, 2011 8:11 am

Pretty sure I remember WB-8 being slightly larger... That was first recollection; now that I think about it I'm not sure at all.


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