Construction of Neutron Grade Fusor

For posts specifically relating to fusor design, construction, and operation.
John Futter
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Re: Construction of Neutron Grade Fusor

Post by John Futter » Tue Jan 22, 2019 4:01 am

Enzo the clue is in your x-ray graph of voltage vs dose
it is your view port ie silicon and or some aluminium somewhere ie ceramic insulator for your high voltage all very good leak sites at about 20-30kV, Stainless holds back until 50kV or more
do not assume that the x-rays follow striaght lines they bounce off higher density stuff like stainless steel and lead multiple times so could come from below, behind, or above.
See one of my earlier threads on a 100kV system in this case direct x-rays were attenuated by the lead concrete filled cinder blocks but our 75kV feedthrough and accelleration tube insulators were letting huge numbers of x-rays go straight up that then bounced off the steel roof straight back down. so 300 micro-sieverts looking at our experiment behind the wall, pointing the counter straight up, 470 milli-sieverts coming straight back down
from the roof
ie suntan time

Bruce Meagher
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Re: Construction of Neutron Grade Fusor

Post by Bruce Meagher » Tue Jan 22, 2019 8:39 am

It’s great you’re continuing to gather data. From the video it would appear you are producing lots of neutrons, but running the test mentioned previously should help your case. My inverse square law comment was about the impact of moving the detector farther from the core, but as you noted it also applies to safety. Since the distance was approximately the same in the two cases my comment does not apply.

One thing others might not have noticed is that you are reporting neutrons in CPS instead of CPM. You’re running ~1000 CPM with the moderator at ~21kV, a few mAs, and ~20mTorr (absolute). Compare that to Joe’s recent runs where he’s getting ~4300 CPM at 43kV, 11mA, 27mTorr (pirani?). Obviously the detector sensitivity and location are different, and you are also using an ion source so the two are not directly comparable. However, calculating the approximate isotropic emission rate from the tube's sensitivity data and distance to the grid (or wall/target for BoT) should be an instructive comparison. Andrew has reported 2.4e6 n/s at ~40kV, 17.7mA, and 9.2 mTorr (pirani?) on his quad ion source fusor. What are you getting?

Finally, I noticed some flashing while looking through the viewport in your video. Are you getting some kind of arc events, or is this just a video artifact?

Good luck and keep up the great work!

Bruce

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Enzo Carter
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Re: Construction of Neutron Grade Fusor

Post by Enzo Carter » Thu Jan 24, 2019 4:19 am

Bruce Meagher wrote:
Tue Jan 22, 2019 8:39 am
Andrew has reported 2.4e6 n/s at ~40kV, 17.7mA, and 9.2 mTorr (pirani?) on his quad ion source fusor. What are you getting?
We will use the gammaspectaculat calculator when we have proven neutrons, until then the data point wont mean so much
Bruce Meagher wrote:
Tue Jan 22, 2019 8:39 am
Finally, I noticed some flashing while looking through the viewport in your video. Are you getting some kind of arc events, or is this just a video artifact?
Yes we sometimes get arching when we frst start up, think its oil from fingers or something burning off the cathode maybe because it seems to go away in minutes of plasma. there are also some video artifacts from noise its clear. sometimes we lose all video.

Its late and I have school tomorrow. but we made a stand for the gs-neutron so the moderator could be removed and replaced without moving the tube. the data looks good. will compile and post a video tomorrow. the bad news is we had to move the gs-neutron detector a bit further away to get this setup so less neutrons and we had to switch to one of my simple coiled tunsten electrode to get a long enough run without a cathode failure. The coin-tungsten rod cathode has much more neutrons but for these long runs it was just too unreliable.
and we also shielded the gs-neutron with a sheet of lead to make sure we brought the noise down.
IMG_7563sm.jpg
we also got a second neutron detector up and running. its a pretty big H3 tube on a ludlum. we had been trying to use it before but it had not been reliable. relianble o r not its a nice backup data point control group.

Everybody has been so helpful!!! thank you.

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Enzo Carter
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Re: Construction of Neutron Grade Fusor

Post by Enzo Carter » Fri Jan 25, 2019 12:06 am

So we have evidence of fusion! We ran the numbers and it shows we are not getting noise. Here is the chart.

We also added a control group neutron counter that is always moderated.
Screen Shot 2019-01-24 at 7.36.45 PM.png
This cathode is in 3D but the chamber is in 2D. The old cathode was a 2D in a 2D chamber. We think this reduces our neutron output but is really something to explore in the future.

Neutron Run
1/23/19

Tungsten Sphere 3x Loops 0.51mm 99.95% pure
28.4kV @ 1.5mA
45 mT (Pirani)
Spellman DXM -70K Supply
2x Neutron Detectors
1. GS-Neutron Tube fixed in place and shielded with lead with removable moderator
2. Ludlum 2000 + H3 @ 1360V Bias Control group counter (always moderated)
Neutrons Counted Neutrons / Minute
GS-Neutron GS Moderated Ludlum-H3 H3 Moderated Delta Time (s) GS-Neutron Ludlum-H3 (-) kV mA Pressure (mT)
Moderated Run 11 Yes 8 Yes 60 11.00 8.00 28.4kV 1.5 45
Un-Moderated Run 4 No 16 Yes 120 2.00 8.00 28.4kV 1.5 45
Moderated Run 38 Yes 24 Yes 195 11.69 7.38 28.4kV 1.5 45
Background Neutron Count 3 Yes 16 Yes 1620 0.11 0.59 0kV 0 0

Average Moderated Neutrons / Min
11.35 N/Min

Average Un-Moderated Neutrons / Min
2.00 N/Min

Background Neutrons
GS-Neutron 0.1 N/min
Ludlum H3 0.46 N/min
IMG_2750sm.jpg
Reactor Front
FrontIMG_1437.jpg
Neutron Detector (moderator installed)
ModeratorIMG_2690.jpg
Neutron detector no-moderator
WithoutModeratorIMG_6737.jpg
Proud Fusinator
EnzoIMG_4673.jpg
Last edited by Enzo Carter on Fri Jan 25, 2019 12:47 am, edited 6 times in total.

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Dennis P Brown
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Re: Construction of Neutron Grade Fusor

Post by Dennis P Brown » Fri Jan 25, 2019 12:18 am

I see you are working hard. So, don't let safety slip by rushing.

As for the final data you have posted, I'm a bit confused. Your moderated reading is 4.0 neutrons/sec and your non-moderated is 11.3 neutrons/sec. Yet when the detector has no moderator, and since it can't record fast neutrons, its signal should drop to near your noise floor. Instead, it is reading a signal three times higher than with the moderator. That does not follow my experience with my system. However, I'm certainly no expert on this issue so others should add their thoughts.

Joe Gayo
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Re: Construction of Neutron Grade Fusor

Post by Joe Gayo » Fri Jan 25, 2019 12:27 am

Enzo,

I applaud your perseverance but honestly, I find the most recent data confusing. You have units of n/min and n/sec used interchangeably. Is all the data actually neutrons per minute?

Consistency and accuracy matter.

Joe

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Enzo Carter
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Re: Construction of Neutron Grade Fusor

Post by Enzo Carter » Fri Jan 25, 2019 12:39 am

Dennis P Brown wrote:
Fri Jan 25, 2019 12:18 am
As for the final data you have posted, I'm a bit confused. Your moderated reading is 4.0 neutrons/sec and your non-moderated is 11.3 neutrons/sec. Yet when the detector has no moderator, and since it can't record fast neutrons, its signal should drop to near your noise floor. Instead, it is reading a signal three times higher than with the moderator. That does not follow my experience with my system. However, I'm certainly no expert on this issue so others should add their thoughts.
Yes in a rush I switched both in the summary :(

Thank you for spotting the issue
Joe Gayo wrote:
Fri Jan 25, 2019 12:27 am
I applaud your perseverance but honestly, I find the most recent data confusing. You have units of n/min and n/sec used interchangeably. Is all the data actually neutrons per minute?

Consistency and accuracy matter.
I fixed it. thanks. all in N/min.

funny i was in a hurry to get to dinner, but no excuse

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Dennis P Brown
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Re: Construction of Neutron Grade Fusor

Post by Dennis P Brown » Fri Jan 25, 2019 10:38 am

Suspected that was the issue. You should re-post the corrected results for comments.

Glad you are making good progress. But again, be careful since fusors do not allow for second chances with their voltage and radiation.

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Enzo Carter
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Re: Construction of Neutron Grade Fusor

Post by Enzo Carter » Fri Jan 25, 2019 12:41 pm

Dennis P Brown wrote:
Fri Jan 25, 2019 10:38 am
Suspected that was the issue. You should re-post the corrected results for comments.
I corrected the original post. Thank you again for catching the mistake so quick.

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Enzo Carter
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Re: Construction of Neutron Grade Fusor

Post by Enzo Carter » Fri Jan 25, 2019 9:09 pm

I wanted to put together q 3 minute video describing my Neutron generating run setup as reading a spreadheet is not the easiest way to see what was going on.

Video of the setup
https://youtu.be/t7sQQlOZzOY


Video of the actual runs the data came from.
ttps://www.youtube.com/watch?v=6GtHVMwKbio&feature=youtu.be

A nice snapshot of the star mode using the round tungsten wire cathode. Not as good as the nickel-tungsten one but more reliable.
Star_Mode_IMG_1666.jpg
there is nothing quite as petty as deuterium plasma

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