Cube fusor build

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Richard Hull
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Re: Cube fusor build

Post by Richard Hull »

I am beginning to see this device as a BOT system fusor! Backing off my position many posts back in this thread. This thing (cube) as long as the ends are kept cool might just implant D in the end caps and at the same time does a good bit of fusion there as all real evidence so well presented here seems to point out. I am also sure fusion is happening in velocity space as well and I'll bet there are good counts to be had from the tube arm walls, just nothing like Jon is getting on the beam line which is obviously where the action is. Of course, in activation work all this beaming will just slow and scatter in the moderator if it does its true job. However, it is nice to concentrate the neutrons at the moderator. That is where beaming comes in real handy. I like it.

Make no mistake, beaming or not, this is still a fusor!....A simple two electrode amateur fusor that is really cookin'! Jon is a master at setting up experiment and relaying great data and results of his efforts. This may be a long thread but a really valuable one that teaches and inspires thoughtful comment and is another way to skin the cat in amateur fusion.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Jon Rosenstiel
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Re: Cube fusor build

Post by Jon Rosenstiel »

Frank,
I’ve found that the inverse square law does not hold up well at small source to detector distances. I ran some tests using a 2” x 2” NaI(Tl) detector and a 10 uCi Cs-137 source and found that in order to get good data the source to detector distance should be no less than 4”. What I’m trying to say is, we probably should not put too much faith in close-in measurements.

As to the anisotropy, take a look at pages 18 thru 20 in the attached paper. (Characterization of Neutron Fields Around an Intense Neutron Generator) I believe this applies to our case, but not really sure. (Dammit Frank, I’m a mechanic, not a physicist) Anyway, I would like to hear your thoughts on this.

Joe,
Nice to hear from you! Thanks for the good ideas, I’ll keep them in mind for future reference.

Richard,
I’ve finally come to the same conclusion; the cube is a BOT device.

Pic of a Monte Carlo neutron flux simulation for a BOT device. Looks quite familiar, huh? Link to complete paper below. (Didn’t attach the paper as it’s nearly 18 MB is size)
https://escholarship.org/content/qt6z74 ... ee762b.pdf

Jon Rosenstiel
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Characterization of Neutron Fields Around an Intense Neutron Generator.pdf
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Frank Sanns
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Re: Cube fusor build

Post by Frank Sanns »

Jon,

Good paper. Nice compilation of lots of information that we have been discussing.

Some conclusions.

1. We agree that close measurements are not good because neither the neutron producing area nor the detector are points. That is why I asked you to throw the top 3 points away on your original curve. I could see they were corrupted because of the near distance. The minimum distance for a good measurement will depend upon the size of the detector. Smaller detectors look more like point detectors at closer distances.

2. Deuterium is a unique beast in that it is such a simple atom, that minor shift between the center of mass of the atom and its charge location (a neutron and a proton), have meaning in the real world. The nucleus is neutral at one end and positively charged at the other. The inverse square at play so and impact from the neutron side is slightly more desirable since there is just a little less repelling charge at that end. By tritium, this effect is much less and the heavier atoms is probably non existent.

3. There is no neutron beam coming out of the ends of fusor. There is a higher probability of of productive collisions when the deuteron is aligned in an electric field that in a random field.

4. The paper also points out that the polarization of the neutrons are also anisotropic. Good luck with that portion of the experiment. Although, it is interesting to think about that as keeping your detector in place and rotating it 90 degrees should also show a difference. Want to handle some cadmium with slots cut in it for the front of your detectors. lol. I AM KIDDING. DON'T EVEN THINK ABOUT IT. Gadolinium is probably not a whole lot better. Maybe Boron Carbide pieces arranged into slats. Just thinking.

5. Your results are most excellent Jon. The effect is not a huge one but you are detecting it. It is important to point out that the confidence in your numbers is in your technique and setup but the repetition of measurements along multiple changes gives the confidence in the numbers. I single reading close and at another distance for a total of two points cannot tell the story. Multiple data points in good agreement gives a good confidence interval to evaluate the data.
Achiever's madness; when enough is still not enough. ---FS
We have to stop looking at the world through our physical eyes. The universe is NOT what we see. It is the quantum world that is real. The rest is just an electron illusion. ---FS
Jon Rosenstiel
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Re: Cube fusor build

Post by Jon Rosenstiel »

Frank, you were correct in your skepticism, allow me to explain.

The following 0-degree/90-degree fast neutron-rate comparisons are based on the assumption that the neutron formation area (NFA) of the cube fusor is centered on (or very close to) the endcap surface. Detector for this test was a 2” diameter by 0.6” thick Hornyak button coupled to a Thorn/EMI 9258KB03 PMT. NIM electronics consisted of the following: Ortec 4001M minibin, Canberra 3102D hv supply, Ortec 113 preamp, Ortec 572 amp, Ortec 550 SCA, Tennelec 534 counter/timer. Both amp and SCA outputs were monitored on an oscilloscope.

My initial plan was to run a 0/90-degree comparison at 3” and 13” to the NFA. (13” is the maximum my setup would allow) At 3” to the NFA the 0-degree position count-rate was about 22% higher than that at 90 degrees. At 13” I expected to find a smaller difference in count-rate between the 0/90-degree positions, maybe somewhere around 15%. I was quite surprised when the 0/90 difference increased to 37%. Additional data points at 5.5”, 8”, and 10.5” did nothing to change things.

At this point I was somewhat baffled so I made a simple drawing of the cube. First thing I noticed was that at 0-degrees there is 0.375” of aluminum between the NFA and the detector vs. 2” of aluminum at 90-degrees. Seems so simple, but something that I had, up to this point, failed to recognize.

Ok, with the above in mind I placed a block of aluminum 1.625” in thickness between the detector and the endcap at the 0-degree position to mimic the 2” of aluminum at the 90-degree position. (Endcap + Al block = 2.0”)

With the 1.625” Al block in place a rerun of the 0/90-degree comparison at 3” and 13” resulted in the following.
At 3” to NFA: 0-deg measurement was 2.3% higher than at 90-deg.
At 13” to NFA: 90-deg measurement was 2.7% higher than at 0-deg.

So, what this is telling me is that the previously measured anisotropy was nothing more than neutron absorption/moderation/scattering in the cube’s aluminum walls. The following Richard Feynman quote comes to mind: “The first principle is that you must not fool yourself – and you are the easiest person to fool”.

Jon Rosenstiel
Attachments
Detector at 90-degree position, 3" from NFA. Shaded areas are 6061 aluminum.
Detector at 90-degree position, 3" from NFA. Shaded areas are 6061 aluminum.
Long-tailed pulse from the ZnS(Ag) loaded scintillator & data pulse from the SCA.
Long-tailed pulse from the ZnS(Ag) loaded scintillator & data pulse from the SCA.
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Richard Hull
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Re: Cube fusor build

Post by Richard Hull »

Great report and observation, Jon. You are giving a lot of good information based on interesting experiment in detection and sorting out anisotropy. Sure, fooling oneself is easy.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Frank Sanns
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Re: Cube fusor build

Post by Frank Sanns »

More great work Jon,

It may just be the physical distance measurement that is giving the effect. If you measured from the outer surface of your Fusor, then you started closer and that would explain the higher numbers that almost met the perpendicular readings as the distance increased. At greater distance, the measurement error on starting distance would be less of contribution.

I am not sure attenuation of neutrons by aluminum is much of a factor. It has a very low cross section so it should not be intercepting many neutrons.

Thanks again for posting the data. Good stuff!
Achiever's madness; when enough is still not enough. ---FS
We have to stop looking at the world through our physical eyes. The universe is NOT what we see. It is the quantum world that is real. The rest is just an electron illusion. ---FS
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