Joe Gayo's lab tour

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Richard Hull
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Re: Joe Gayo's lab tour

Post by Richard Hull »

Yes, Any remball system that is in calibration can be used regardless of its volume, shape or size to back out from its reading to n/cm sq., (flux), as long as you know where on the curve 2.5mev neutrons represents the rate displayed for a specific flux.
From this, you can then back figure to total isotropic emission based on distance from the center of the rem ball to the fusor.

Note: This assumes good calibration of the rem ball integrated system. Such back figuring, as I have noted many times, are +/- 20% with luck!

+/- 5% in neutron flux demands recently calibrated new instruments with an absolutely stable, invariant neutron source. In 90% of all neutron systems, especially portable systems it is not about super accurate readings, but more on the order of "will I live?" or "Should I get the hell out of here" or "If my reading is low or moderate and stable in my environment, how long should I remain in this field based on back of envelope calculations", (based on personal or work related total dose limits).

99% of all fusors that actually attempt fusion will not even move a needle of the more coarsely calibrated instruments.

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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
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Re: Joe Gayo's lab tour

Post by Joe Gayo »

The strategy was to use both calibrated detectors to provide greater confidence in the result. For example, the detector at 160cm has been well characterized, shielded from electronic interference, and precisely instrumented.
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Re: Joe Gayo's lab tour

Post by Richard Hull »

That's the best way to do it. I used many runs with a bubble detector over varying period run times and reductions. I used the data to create a lot of decent statistics to calibrate my fixed 3He tube system within Nim instrumentation. All data was taken within 4 weeks of my receiving my bubble dosimeter. Once calibrated, I created a multiplication factor to jibe the total digital counts over one minute to give me the total iso emission rate. The drawback is that since calibrated in 2005, I have never moved the detector in moderator or the fusor...ever!

I know I could do yet more calcs for the system to keep it more or less in cal with a move, but the background scattering changes for the neutrons by the massive nearby wood background in the original calibration statistics would foul the calibration in a move. With fusors producing low neutron levels like we tend to work, (~1 X10e6), we must be ever mindful of how materials in and around the detectors and fusor can influence any calibrated count if we are constantly moving the counter and or fusor systems about!

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
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Re: Joe Gayo's lab tour

Post by Joe Gayo »

I have two fresh bubble dosimeters on order for absolute certainty.

I believe several factors are driving these higher numbers (some recent runs are significantly higher than previously reported).

- 75kV @ 12mA max
- I've performed comparative runs at varying axial magnetic field strength (0 - 500 gauss) and 500 gauss at the cathode seems best
- The vacuum has continually improved (as the chamber is baked out with high power runs) meaning higher deuterium purity
- Wall loading with a high frequency of runs
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Re: Joe Gayo's lab tour

Post by Joe Gayo »

** UPDATE **

28 bub/mrem dosimeters confirm the following:

70 kV @ 12.8 mA, 19.5 mTorr D2, 12.6M n/sec TIER
75 kV @ 19.0 mA, 19.5 mTorr D2, 20.7M n/sec TIER

I cycled the power for 5 seconds to limit the number of bubbles to make counting easier, but electronic detection verified the output level for separate 30-second runs. I alternated between 5-second and 30-second runs over 10 times and the results were all consistent within 10% (n/sec) and the same operating conditions.
Detector Setup
Detector Setup
12.7cm, 51bub, 5 second exposure
12.7cm, 51bub, 5 second exposure
Calculated Results
Calculated Results
Videos:
https://youtu.be/qmFA1BWLVOc
https://youtu.be/JXSJxD4p6uw
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Richard Hull
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Re: Joe Gayo's lab tour

Post by Richard Hull »

Fabulous work. The extra volts, current and pressure in addition to the compact fusor chamber really seems to have done the trick. Unfortunately, the extended runs at those levels to activate things is limited in the case of those elements that have half lives of the created isotopes in excess of a number of minutes. Fabulous numbers output for 5 seconds wins great bragging rites.

Silver and Indium ought to do well, however, due to the sheer number of neutrons even if the large total iso emission numbers come in such short length bursts. When those numbers can be sustained over two or more minutes then a window would open on a number of activation possibilities.

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
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Re: Joe Gayo's lab tour

Post by Joe Gayo »

The 5 seconds was just to limit the total number of bubbles to a manageable number to count. The electronic detection indicates I can run at this level for about 60 seconds at the moment.
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Re: Joe Gayo's lab tour

Post by Rex Allers »

Great continuing work, Joe.

You mentioned,
- I've performed comparative runs at varying axial magnetic field strength (0 - 500 gauss) and 500 gauss at the cathode seems best

I don't think a magnetic field has been part of many other fusors that I am aware of. Can you share any more details about the kind of effect the magnetic field has on your observed neutrons?

I realize your cylindrical configuration is rather different than most others have used. Any comments on dimensions of what you are running now, might be interesting too.
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Re: Joe Gayo's lab tour

Post by Richard Hull »

New, smaller and different geometries! This is all great work and should serve to guide future efforts in amateur fusion. The second amateur fusion revolution of innovation begins!

As I have noted from the beginning, back in 1997, it was not fusion, per se, that started me on this path, but the search for a stable source of neutrons for amateur experimentation that was safe and did not involve permanently radioactive sources. I will continue to watch these efforts with intense interest.

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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
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Re: Joe Gayo's lab tour

Post by Joe Gayo »

The axial field assists in the stabilization of the discharge and in a cylindrical system establishes a situation where the main axial beam is the preference for ions and electrons.

I'm still developing tests to validate the following speculations:
- Magnetic shielding of cathode
- Improvement of ion confinement (even if a minuscule number, a small chamber has a large field gradient and the additional energy gained could be significant)
- Higher plasma density

Current Magnetic Field Simulation
MagField.png
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Dennis P Brown
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Re: Joe Gayo's lab tour

Post by Dennis P Brown »

I too used a bubble detector to first determine that a smaller chamber does, in fact, lead to greater fusion. I did this about a year or so ago. I am glad to see this work taken further and with better accuracy. I agree with Richard, and why this also caught my attention for confirmation - smaller chambers (i.e. distance from cathode to ground and higher deuterium operating pressure) does result in significantly higher fusion rates. Your results are very good and effort outstanding.
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Re: Joe Gayo's lab tour

Post by Dan Knapp »

Joe

Can you explain your magnetic field plot? This appears to be a half image of the cross section of two ring magnets (that would also be cathodes?). Is this correct?

If so, it is not clear how you would get magnetic shielding with the field lines terminating on the cathodes.
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Re: Joe Gayo's lab tour

Post by Joe Gayo »

The cathode is in the center along the axis of the magnetic field (the plot is oriented vertically but the actual layout is horizontal)

(P.S. I'm working on a paper that I planing on submitting to a journal to discuss this system.)
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Re: Joe Gayo's lab tour

Post by Robert Dwyer »

Neutron counts into the 1e7 range with a smaller chamber! Wow! I never though I would see it. This is a great system. It is cool to see that you are using software like FEMM to investigate your fields. It would be interesting to see plots of the E-field in your setup as well.

After going back through my data and reading some articles, I had gotten the mindset that the high operating pressures were in fact hurting as the ions would collide with too many neutrals not allowing them to reach higher energies. It appears I was wrong. Perhaps these systems want more power (voltage and current) in the high pressure regime, or perhaps my old system was not clean enough to see the big numbers... Either way, great job.
Of course you also have that background field, who knows how much of these improved numbers come from each of things, or any combination of these things.
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Re: Joe Gayo's lab tour

Post by Joe Gayo »

How about a PIC simulation that shows the time evolved potential field:
https://youtu.be/wEO5Ewo_H_w (Note: The cathode is at 0V and the chamber walls at 50kV)
Last edited by Joe Gayo on Wed Jun 19, 2019 1:56 pm, edited 1 time in total.
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Re: Joe Gayo's lab tour

Post by Scott Moroch »

I was interested in your 7-hole grid design. The models support the observations.

Simulation Video: https://www.youtube.com/watch?v=P5lp3Wu ... e=youtu.be

Initial distribution is circular, launched from the left with 0 KE. Grid at -60kV with respect to the chamber.
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Image 2.PNG
Image 1.PNG
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Re: Joe Gayo's lab tour

Post by Rex Allers »

So PIC simulation is new to me. From a little searching I assume this is
particle-in-cell computation, a method for simulating plasma.

This wiki covers the basics -- https://en.wikipedia.org/wiki/Particle-in-cell

Looking at your plot in the youtube link, it seems the simulation only represents a quarter of a slice through the whole device. Symmetry means the fields in the other three quadrants are just mirrors of the one calculated.

Not needed, but I captured one frame from your video and did the mirroring of the main plot window, so the field in the whole device would look like this.
PIC sim full.png
I assume the elapsing time as the video plays reflects actual time for the plasma to evolve in the chamber. Does the simulation give the actual time represented across the video?

I have one small question about the voltages. You said the chamber was at 60 kV. Looking at the sim plots, the two edges that seem to represent the chamber edges appear to always be at 50 kV. As the fields evolve some areas get up to 60 kV but those outside edges are still at 50 kV. Does this mean the external excitation voltage applied is 50 kV?

What software did you use to run this?

Thanks for sharing.
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Re: Joe Gayo's lab tour

Post by Carl Willis »

Joe, this is a top-flight effort, and I am thrilled to see what appears to be a novel paradigm in fusor efficiency developing in your work.

The regime of high pressure, small electrodes, high potential, and high neutron yield is undoubtedly a new domain worthy of further attention.

Have you provided a detailed discussion of your electrode geometry on this board? I apologize if I missed it; I have mostly been away from the forums the last few years. But it's progress like this that will make me come back!

Thanks for sharing your impressive project here.

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Re: Joe Gayo's lab tour

Post by Joe Gayo »

@Rex Yes, in this simulation the applied potential difference is 50kV. You are correct about the symmetry of the simulation as well. The animation represents microseconds. The software is Starfish (https://www.particleincell.com/starfish/ - Free!)

@Carl Thanks! The electrode geometry is discussed in my lab tour video on YouTube. I'm constantly refining the electrode geometry based on simulation and testing. The next "knob" to turn will be material selection.
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Re: Joe Gayo's lab tour

Post by Jon Rosenstiel »

Joe,

Awesome work, and congrats on the ultra-mega neutron numbers, you are the man! After many, many years the baton has finally found a new home... about time! And you didn't just up the ante a little bit, you blew it to smithereens!

In your video you mention that your device's neutron output on axis with the plasma beam is about 2 times that of the neutron output measured at right angles to the beam. As your device is not truly isotropic in neutron output it may be more accurate to quantify neutron flux in neutrons/sq-cm/second.

Jon Rosenstiel

PS: Anyone have a foot or so of 4" x 4" 6061-T6 bar stock they wanna part with?
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Re: Joe Gayo's lab tour

Post by Dan Knapp »

In regard to the PIC simulation, please be advised that a 2D simulation does not give a valid representation of a system with axial symmetry.
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Re: Joe Gayo's lab tour

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With the 4 X4 6061 request from Jon, coupled with his machining abilities, I imagine he has ideas. I am still musing over using my 6 way 2.75 CF cross to replaced fusor IV.

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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
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Re: Joe Gayo's lab tour

Post by Joe Gayo »

@Dan Sure it does ... it's an axially symmetric (RZ) code/solver. I actually, know the individual that wrote Starfish (his Ph.D.) and he and I are working together on simulations.
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Re: Joe Gayo's lab tour

Post by Dan Knapp »

The description on the link to the Starfish code describes it as a 2D simulation. I overlooked the mention on another page that it allows the selection of a Cartesian or axisymmetric system, which requires a more sophisticated RZ solver. I guess I was surprised that someone would be making the more sophisticated software freely available. I stand corrected. My apologies.
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Re: Joe Gayo's lab tour

Post by Joe Gayo »

@Jon - Thank you for the kind words and the tour of your impressive lab!

@Everyone -
I have a -100kV @ 20mA power supply arriving in the next few weeks and will begin experimenting with different cathode/anode materials. Based on some preliminary results the Aluminum construction may be contributing to the strong results.
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