Joe Gayo's Fusor - Neutron Detection Upgrade

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Joe Gayo
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Joe Gayo's Fusor - Neutron Detection Upgrade

Post by Joe Gayo »

Upgraded detection to BF3 tube with TC174 preamp
IMG_1025_sm.jpg
Clean detection pulse with shaping
IMG_1026_sm.jpg
90n/sec @ 27mTorr, 43kV, and 10mA
IMG_1041_sm.jpg
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Richard Hull
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Re: Joe Gayo's Fusor - Neutron Detection Upgrade

Post by Richard Hull »

Looks great with your new, far superior tube and windowing. Once again, tube in vs tube out data?
I think you are doing fusion. Let's see the comparison now.

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 Fusor - Neutron Detection Upgrade

Post by Joe Gayo »

All done during the same run ...
27 mTorr D2
43 kV @ 11mA

90 sec (with moderator): 8186 counts
90 sec (no moderator or oven): 13 counts
90 sec (with moderator): 7993 counts

————————————
Activation Run:

4g Ag 0.5 mm Foil 0.15m distance in oven

300 sec @ 80-100n/sec

60 sec 141 counts
300 sec background avg 44

(Activation Edited: Previous math error)
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Joe Gayo
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Re: Joe Gayo's Fusor - Neutron Detection Upgrade

Post by Joe Gayo »

Adjusted the P/Z on the shaping amplifier to improve the return to zero (runs still consistent with previous measurements)

Next steps:
- Bubble dosimeter calibration
- Upgrade feedthrough and power supply to 70kV
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Richard Hull
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Re: Joe Gayo's Fusor - Neutron Detection Upgrade

Post by Richard Hull »

Joe, welcome to the neutron club. What a difference with the 3He tube. over the Russian tube. As you have a gauge and have used both tubes. You might go back to assist everyone with a future Russian tube and give a report on how to get it to function even marginally for neutron detection.

Re-bias it so that the returns look close to your 3He tube or as close as possible.

Report the tube number, your bias, the input circuit component you used as you did before and what the differences between the x-ray component and the neutron components look like on the scope picture and how you might best window out non-neutronic responses in the tube.

I genuinely feel that the Russian tube is a good tube, but it just can't compete in the far more casual world of the 4 atmosphere 3He tube for ready and stunning results unless it is critically handled from the front end to the final windowing.

In your report give us a qualitative feel for both tube experiences you have had.

You may be the only person here who used both tubes and have a special perch to tweet from on this matter.

Thanks

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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Dennis P Brown
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Re: Joe Gayo's Fusor - Neutron Detection Upgrade

Post by Dennis P Brown »

Congratulations on really good work; few get both neutron detection via a tube and Ag activation for their first runs to join the neutron club.
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Richard Hull
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Re: Joe Gayo's Fusor - Neutron Detection Upgrade

Post by Richard Hull »

A great example of having the "right stuff", in two cases.... In the first case both Joe's carefully working, taking a bit of direction, learning and adjusting. The second case was obtaining the right stuff in that matched pre-amp and 3He tube and windowing it to perfection. That last run report was a classic study of what we love to see from the "tube-in vs. tube-out" acid test preformed in a virtually perfect detection setup and in good fusor operation, the latter he seemed to have already mastered as we dragged him through a lot of hoops. He now has the touch that few here ever master to the fullest degree.

I hope Joe never felt pressured or dis-believed. In the end it doesn't really matter what he felt, it is what he did. "He had guts and guts is enough" ...He won!

I hope he sticks around after his win. We can use another hands-on, "git er done", winner.

Oh, I assume he spent a bundle. That helps but, only up to a point

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 Fusor - Neutron Detection Upgrade

Post by Joe Gayo »

Not surprisingly, Richard’s feedback was extremely valuable and provided the helpful nudge.

I feel as if the journey has just begun. Operational experience (and wall loading?) is pushing count rates higher and higher (140/sec last run), but I still need to calibrate with the bubble dosimeter. Activating silver seems easy and I want to setup a gamma spectrometer and run indium and manganese.

I built my 50kV supply with an inverter I designed and an old Glassman multiplier stack. Now I’m doing the same thing with a Spellman 70kV stack. My goal is 5M n/sec and to use it for real science (neutron optics, etc.)
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Re: Joe Gayo's Fusor - Neutron Detection Upgrade

Post by Dennis P Brown »

I would think that your design for your 50 kV power supply would be a great post. You should consider that since that would be both useful and insightful for other people here. Also, maybe include your construction of your new 70 kV system, as well, as it progresses. Sharing methodologies and practices is what this forum is all about.
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Re: Joe Gayo's Fusor - Neutron Detection Upgrade

Post by Joe Gayo »

Just to be clear: my fusor only uses a dual stage rotary vane pump (Pfeiffer Duo 2.5) with a base pressure of 3mTorr.
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Richard Hull
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Re: Joe Gayo's Fusor - Neutron Detection Upgrade

Post by Richard Hull »

My First fusion was with a mechanical pump that could hit 5 microns, backed by a micromaze that bottomed my TC gauge. (actual vacuum unknown). The best I ever did with fusor III was 250kn/s but I never got above 32 kv. Now that we are into the wall loading concept, day to day operation will see a bit of improvement. In addition, when fusor III was in operation I have far less knowledge and much reduced neutron detection (Eberline PNC-1) a good counter, but with a small Nancy Wood BF3 tube in it.

A word of advice. When you have your bubble detector fix forever your neutron tube and moderator or mark its position well. Calibrate your counter using the bubble detector. over many days and many runs recording all data counts during a run and the number of bubbles per run. Do this as many times as you can over the life of the bubble detector. I have many, many pages of such data. In the end, Based on the bubble detector's rmem dose back figure to the digital counters run total counts, you will arrive at a multiplication factor for future total counts that you can use in future long after the bubble detector is dead to arrive at a total isotropic emission per second of neutrons from your fusor. The accuracy of the multiplier will rely highly on the number of data samples taken over time. More samples, obviously the better the statistics and the resultant multiplier.

My multiplier turned out to be 21.6. I backed it off to an easy and conservative 20.0.

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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Joe Gayo
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Re: Joe Gayo's Fusor - Neutron Detection Upgrade

Post by Joe Gayo »

Will do with the bubble detector!

I assume when you say micromaze you are referring to a sorption pump?
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Re: Joe Gayo's Fusor - Neutron Detection Upgrade

Post by Joe Gayo »

The following is for those who are looking for the lowest financial bar for a neutron producing fusor:

If you have reasonable strong electronics knowledge, then a sub $1000 fusor is possible maybe even sub $500.

** Use a high quality two-stage rotary vacuum pump (Edwards, Pfiffer, Precision Vacuum, etc.) - no diffusion or turbo pump required. A base pressure bellow 7mTorr seems sufficient. This also means you only need a thermocouple vacuum gauge.

** KF 40 cross makes an excellent chamber. KF fittings are cheap and simple to assemble / disassemble.

** Purchase NIM BIN equipment even if it's not guaranteed to work. Schematics are readily available in the manuals. The common failure points are cold solder joints, failed output BJTs, and tantalum capacitors. (I fixed/refurbished my NIMs and preamp)

** Purchase the OEM models of Spellman or Glassman power supplies, or better yet, units with just the multiplier stack (viewtopic.php?f=11&t=12625)

** Spark plug high voltage feedthrough - https://www.ebay.com/itm/Metric-M14-x-1 ... 2480729252 with a Champion J99 599 industrial spark plug. As long as the air side is sufficiently insulated you should be able to reack 20kV+.

My fusor was around $720.
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Re: Joe Gayo's Fusor - Neutron Detection Upgrade

Post by Richard Hull »

The micromase was pushed by Lesker for a few years and is no longer available. It was great and could warrant about one order of magnitude below a good mechanical pump that could go under 10 microns on its own. It had its own internal heater to purge bad stuff out and clean itself up. It was found by me that a full one hour pumping, heated purge of the micromaze and gas ballasting for each days run of the fusor. This hassle might have been the complaints around their micromaze and its demise. I did not mind it in those early days.

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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Joe Gayo
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Re: Joe Gayo's Fusor - Neutron Detection Upgrade

Post by Joe Gayo »

Bubble detectors arrived (55 and 54 bub/mrem)!

Did a quick 30 second run at near full power 45kV, 15mA, and 28mTorr.
Dosimeter has a holder that places it 22.4 cm from the center of the chamber.

5 bubbles ... 545,000 n/s TIER
IMG_1050_sm.jpg
Obviously I have more runs planned, but I couldn't wait to post.
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Re: Joe Gayo's Fusor - Neutron Detection Upgrade

Post by Dennis P Brown »

Very nice results; Bubble detectors are useful and the gold standard.

I too checked mine with a 22 bubbles/rem - turns out my neutron detector wasn't too far off (around 170 k neutrons/sec.) I did two chamber sizes with two bubble measurements to show that halving the fusor volume nearly doubled the neutron count (gas pressure and voltage all the same.) Was hoping someone else would look into that question and do more definitive experiments - one experimental run is not exactly proof.
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Re: Joe Gayo's Fusor - Neutron Detection Upgrade

Post by Cristiano_Machado »

Hello Joe,

Nice work and I am happy the BD have arrived earlier than expected.

I am trying to send you a private massage about the BD, but I don't know why the messages can't go out of my outbox. Can you contact me about our deal? Fell free to email me directly (c_machado@yahoo.com).

Regards,

Cristiano
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Re: Joe Gayo's Fusor - Neutron Detection Upgrade

Post by Pablo Llaguno »

Great work Joe!

I am curious as to how you set up your vacuum and D2 system. Does your setup use any valve between the pump and chamber? If not, how do you manage to not waste so much D2?
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Re: Joe Gayo's Fusor - Neutron Detection Upgrade

Post by Joe Gayo »

I do have an isolation valve but I do flow the D2 and waste a decent amount at this point. My runs are fairly short.
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Re: Joe Gayo's Fusor - Neutron Detection Upgrade

Post by Joe Gayo »

Good statistical run...

98 bubbles in 180 seconds, 12.5 cm distance

554,000 n/sec TIER

45kV 16mA

28mTorr
42B17938-41F7-44CF-91FD-AB00978F44F7.jpeg
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Joe Gayo
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Re: Joe Gayo's Fusor - Neutron Detection Upgrade

Post by Joe Gayo »

IMG_1071_sm.jpg
23Jan19-8am-Run.png
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Re: Joe Gayo's Fusor - Neutron Detection Upgrade

Post by Dennis P Brown »

Outstanding data processing and presentation. Perfect example of a top level experiment.

If you had done the IEEE paper, it would have been done correctly with carefully measured results.
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Joe Gayo
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Re: Joe Gayo's Fusor - Neutron Detection Upgrade

Post by Joe Gayo »

Hovering right around the 1 Mega n/sec mark ... 950k to 1050k per second ... once I upgrade my feed through and push well past 50kV the barrier should be definitively broken
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Re: Joe Gayo's Fusor - Neutron Detection Upgrade

Post by Richard Hull »

Silver will activate easily for you at you current level.

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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Joe Gayo
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Re: Joe Gayo's Fusor - Neutron Detection Upgrade

Post by Joe Gayo »

Correct, Silver is easy for my setup. I’m finishing my gamma spectrometer to work with Indium.
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