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Joe Gayo's lab tour

Posted: Sun May 26, 2019 4:07 pm
by Richard Hull
I just tuned into Joe's lab tour. A fabulous effort that shows a continuing interest in IEC fusion. A real fine example of researching this effort.

I have placed this in the construction forum due to his detailed construction account. He is either very well off or very talented across the board as his recent work is with multiple machined 6061 aluminum cubes. This is far beyond the high schooler "I wanna' do fusion" efforts so common here. It is all about thoughtful application of talents and wise use of resources.

Joe doesn't believe in the best of everything and is is more interested in getting the job done. He is capable of assembling multiple NIM modules, vacuum pumps, etc to get the job done regardless of brand name. It is obvious to the meanest intelligence that he is multi-faceted, multi-talented and if he doesn't know something, he soon will via reading and by the "doing" plus, pouring on the coals needed to press on. A rare breed, indeed.

I could see this in just his past postings, but the lab tour just confirmed and boosted my respect for his efforts here.

He has more than verified that small volume fusors, (his small cubes), allow for high pressures for deuterium fuel which in the standard Lawson criteria increases fusion. (Fuel density) This has been an ongoing talking point here for about two years. At the amateur end this makes the needed high voltage tough to get into these small chambers without arcing for the novice HV amateur.

The aluminum, as he notes, is a low emitter of electrons. This is something new to consider for those with machining skills or plenty of money and the verve needed to take this into their own lab.

As an amateur machinist, the cube is an easy item to machine in a four jaw chuck on a suitable lathe or even easier on a milling machine equipped with a rotary table in the hands of a tolerably good machinist. Aluminum, in a free cutting alloy is a dream to machine. Tool speeds are not hyper critical as with SS, though still important. Tool wear it virtually zero and only tool clogging at terribly wrong speeds on softer alloys needs attention.

The whole fusor biz gets a good bit easier if you have a lathe and the milling machine and know enough to use them, not necessarily with high precision, but with a good ability to know where to whack metal off an item. Precision comes with time and experience. Interestingly, I was forced to learn some machining skill in the 70's and 80's in amateur astronomy. It was mostly whacking metal into shape, but I was forced to learn how to thread, internally and externally as many oddball, useful, pre-threaded items came my way which needed coupling to telescopes and mounts.

I know a great machinist who I respect mightily, but he avoids any threading outside of tap and die work. Threading is typically the last cutting on most larger pieces. This means they are finished items and a mistake in threading could kill all the preceding work. As my friend is hyper precise and does beautiful satin finished items, I guess he fears ruining good work.

Joe either hires good machinists or is a competent one himself.

In the electronic erector set world of NIM, Joe is either very capable from the get go or he is a quick learner.

Regardless he has mastered many skills never even attempted by the vast majority of folks who land here. Admittedly many are teenagers and have a lot of life yet to live and learn many things that will hopefully propel them forward. They are not to be faulted for their youth or its inexperienced exuberance.

It is more often the bit older Joes, the Jons and the Carls who have the verve, knowledge and ability to do that tends to inspire us, and often make it look all too easy.


Richard Hull

Re: Joe Gayo's lab tour

Posted: Sun Jun 02, 2019 6:47 pm
by Joe Gayo
Thank you, Richard, for the kind words. I've been fortunate to have studied power electronics and physics which gives a solid foundation to build, modify, and repair NIMs, power supplies, and controllers. I performed all the mechanical design but used a local machinist who is a friend and was willing to be compensated with traded services.

I have some exciting news from my lab, [name deleted] the latest electrode geometry was able to further increase the operating pressure and combined with a custom 70kV power supply I was able to sustain 7.5M+ n/sec TIER! https://youtu.be/MGOdzLYGoks & https://youtu.be/LtMH4XQClgc
Custom Power Supply
Custom Power Supply
DXM70N Transformer and Multiplier with Custom Driver/Control
Setup
Setup

Re: Joe Gayo's lab tour

Posted: Mon Jun 03, 2019 2:12 am
by Joe Gayo
Calculations
Calculations
This may be the highest Q for an amateur device.

Re: Joe Gayo's lab tour

Posted: Mon Jun 03, 2019 4:26 am
by Dennis P Brown
Very nice setup and excellent work.

Relative to your claim for your overall Q, while Richard is the final authority, I'd suggest that in order to better support the Q value obtained (and aid others in their work here), that you should show, in detail, how you arrived at the various values in your display. I would especially suggest you provide a detailed discussion of your calculations and what they are based upon. Your bubble detector, is course, the gold standard for the neutron flux. So include a photo of its results (with both the 300 bubbles and its mfg. rating.)

For us here, those are black box values so it would be informative to see the details. For instance, a back calculation from your value of 30 mrem to a neutron flux would be useful for many here trying to understand that issue for a amateur fusion device. Also, you didn't include the system pressure that you used - that would be an important addition to the display.

Again, impressive work.

Aside: I would like to clarify one data display: For your mrem value, that would be 30 mrem for 3600 seconds as derived from the bubble detector (300 bubbles)?

Re: Joe Gayo's lab tour

Posted: Mon Jun 03, 2019 5:24 am
by Richard Hull
I looked at and studied Joe's work and it looks very well done and tied up with a bow on it.

Dennis is correct though, a photo of a bubble detector chocked full o' bubbles would be nice.

I would say that in the past almost all bubble detectors that were exposed and photographed might have had 10-50 bubbles for a total of ten minutes of a single hard run.

3600 seconds, (one hour), naturally, if run full bore over that period, with the 300 bubble result, would lessen any need for statistics due to the number of bubbles over the finish line and the long period of exposure.

A great report. I would love to have seen the x-ray dose using a dosimeter at the same range of the 3He detector. Most 3He detectors of the P3 and P4 types claim they may be immersed in a 5 roentgen x-ray field before detection might be compromised. I doubt if you had more than a 1R field at that range. The field might be back figured from a 200 mrem pen dosimeter after a 5 or 10 minute run at near 70kv. It would be fearsome for sure....Of course, the Aluminum bodied, block fusor would not produce x-rays at the level of an SS chamber operated at the same potential.

Richard Hull

Re: Joe Gayo's lab tour

Posted: Mon Jun 03, 2019 11:49 am
by Joe Gayo
I have three neutron detection systems:

1. A BF3 tube / LDPE moderator placed 40 cm from the cathode
2. A BF3 tube / LDPE moderator placed 160 cm from the cathode - calibrated with 54 bub/mrem dosimeter (Feb - April)
3. Ludlum 12-4-7 (x10 scale, slow 22 sec) placed 50.8cm from the cathode - calibrated by an outside lab

Detectors 2 (custom controller monitoring SCA pulses) and 3 (with camera) were continuously monitored.

The way I used the calculator from Bee Research is as follows:
- The sustained dose rate indicated by the Ludlum 12-4-7 was 300 uSv/hour (entered in bubbles/counts)
- 10 uSv/hour = 1 mrem/hour (entered in detector calibration since the detector was calibrated to read uSv correctly)
- Entered detector distance (50.8 cm)
- Exposure time was set to 1 hour (3600 sec) to convert rate to dose (rate meter isn't showing cumulative, but instantaneous rate averaged over 22 seconds)

This calculation is very similar to viewtopic.php?f=6&t=2899#p12409

The rate calculated from the Ludlum 12-4-7 was within 10% of detector 2. (Detector 1 was not monitored)

The full parameters of operation are as follows: 72kV and 6.9mA @ 18mTorr

(I'll follow-up in a future post with x-ray dosimeter readings at the detectors ... currently, the dosimeter is at the operator's computer)

Re: Joe Gayo's lab tour

Posted: Mon Jun 03, 2019 1:06 pm
by Dennis P Brown
So if I follow, is the device right next to your fusor a bubble detector in its count housing? Is its response the 10 bubbles/mrem shown as the value in the display? And the value of 300 was obtained for the 3600 second run? Or are these values derived from the other detector via a previous calibration run?

What is the point of the other detectors (@ 40 cm and 160 cm) if they are not being used? If you have data from these can you include their values, detector areas and calibrated values?

I am assuming that you are using a spread sheet to calculate the various displays. So what formulas are you using in the spread sheet to convert the mrem, uSv into neutron flux? Can provided the area of the detector used at 50.8 cm (Ludlum 12-4-7)?

Again, a photo of the bubble detector is needed since all your data is based on that device either by calibration or direct detection.

Re: Joe Gayo's lab tour

Posted: Mon Jun 03, 2019 1:16 pm
by Joe Gayo
A second detector was used (@160 cm), it read 7.8M n/sec based on it's previous calibration. The detector @40cm wasn't monitored because it's un-calibrated.

The bubble detector I have is now expired. The bubble detector was used previously from runs between February and April (viewtopic.php?f=18&t=12623&p=82120) to calibrate the electronic detection.

Also, I have all these detectors because I have 2 devices that I compare and contrast, which allowed me to optimize the cathode geometry.

Re: Joe Gayo's lab tour

Posted: Mon Jun 03, 2019 4:40 pm
by Dennis P Brown
Thanks for that information. That helps clarify what you did.

So I can properly calculate your results, what is the collection area of your detector?

Re: Joe Gayo's lab tour

Posted: Mon Jun 03, 2019 4:53 pm
by Joe Gayo
The is Ludlum sphere has a surface area of 1195 cm^2 and cross section of 299 cm^2

Maybe I'm missing something, but the Ludlum is calibrated to show uSv/h with a inverse RPG curve (that's pretty accurate at 2.45MeV) so the detector area is already considered in the measurement. Isn't the calibrated dose rate at a distance all that is necessary for a neutron rate?

Re: Joe Gayo's lab tour

Posted: Mon Jun 03, 2019 5:39 pm
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.

Richard Hull

Re: Joe Gayo's lab tour

Posted: Mon Jun 03, 2019 10:27 pm
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.

Re: Joe Gayo's lab tour

Posted: Tue Jun 04, 2019 2:12 am
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

Re: Joe Gayo's lab tour

Posted: Wed Jun 05, 2019 10:42 am
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

Re: Joe Gayo's lab tour

Posted: Sun Jun 16, 2019 7:43 pm
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

Re: Joe Gayo's lab tour

Posted: Sun Jun 16, 2019 11:27 pm
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

Re: Joe Gayo's lab tour

Posted: Sun Jun 16, 2019 11:33 pm
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.

Re: Joe Gayo's lab tour

Posted: Mon Jun 17, 2019 8:12 am
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.

Re: Joe Gayo's lab tour

Posted: Mon Jun 17, 2019 1:20 pm
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.

Richard Hull

Re: Joe Gayo's lab tour

Posted: Mon Jun 17, 2019 8:42 pm
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

Re: Joe Gayo's lab tour

Posted: Tue Jun 18, 2019 5:15 pm
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.

Re: Joe Gayo's lab tour

Posted: Tue Jun 18, 2019 5:43 pm
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.

Re: Joe Gayo's lab tour

Posted: Tue Jun 18, 2019 5:55 pm
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.)

Re: Joe Gayo's lab tour

Posted: Tue Jun 18, 2019 8:09 pm
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.

Re: Joe Gayo's lab tour

Posted: Tue Jun 18, 2019 8:21 pm
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)