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 » Mon Jun 03, 2019 9:39 pm

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.

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
Retired now...Doing only what I want and not what I should...every day is a saturday.

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Re: Joe Gayo's lab tour

Post by Joe Gayo » Tue Jun 04, 2019 2:27 am

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 » Tue Jun 04, 2019 6:12 am

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
Retired now...Doing only what I want and not what I should...every day is a saturday.

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Re: Joe Gayo's lab tour

Post by Joe Gayo » Wed Jun 05, 2019 2:42 pm

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 » Sun Jun 16, 2019 11:43 pm

** 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.
IMG_1462_sm.jpg
Detector Setup
IMG_1463_sm.jpg
12.7cm, 51bub, 5 second exposure
20M_06162019.PNG
Calculated Results
Videos:
https://youtu.be/qmFA1BWLVOc
https://youtu.be/JXSJxD4p6uw

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Re: Joe Gayo's lab tour

Post by Richard Hull » Mon Jun 17, 2019 3:27 am

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
Retired now...Doing only what I want and not what I should...every day is a saturday.

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Re: Joe Gayo's lab tour

Post by Joe Gayo » Mon Jun 17, 2019 3:33 am

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 » Mon Jun 17, 2019 12:12 pm

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 » Mon Jun 17, 2019 5:20 pm

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.

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
Retired now...Doing only what I want and not what I should...every day is a saturday.

Joe Gayo
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Re: Joe Gayo's lab tour

Post by Joe Gayo » Tue Jun 18, 2019 12:42 am

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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