Successful neutron emission from new fusor

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Rich Gorski
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Successful neutron emission from new fusor

Post by Rich Gorski »

Hi everyone,
This is my first post on fusor.net showing the details of our first fusor build which is called Sci-Comp-build #1. The image below shows a rather over exposed photo of Sci-Comp B#1 operating in star mode. Conditions are V=-37kV, I = 20mA at a deuterium pressure of 15 mTorr. We measured a neutron flux of about 4x10^6 n/s on a B10 proportional tube (crude calibration, not traceable). We have also attempted a silver activation run which resulted in a weak but noticeable beta emission curve with a reasonable half life as expected from the decay of 108Ag. Please look at the attached pdf file for a detailed description of the Sci-Comp-B1 build. I would be happy to answer any questions about its construction and results.

If you are planning to build your own fusor please be aware of the two main dangers in building such a device.
1. Danger of electrical shock: The high voltage (>30kV) and currents (>5mA) needed to generate a neutron flux can be hazardous if not properly handled and shielded. If you are inexperienced in dealing with high voltage please gain the help of someone with such experience.
2. Danger of X-radiation. X-radiation will become significant when your device operates above 20kV at several milliamps of current. Our stainless steel vacuum chamber was shielded with 1/16" of lead sheet to absorb the x-radiation. We also use a personal dosimeter to monitor the dose rate received when we were running above 30kV. We occasionally registered a low but non-zero dose even through the lead shielding and standing 10 feet away from the reactor.
IEC fusor Sci-Comp 9-13-22.pdf
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IEC fusor Sci-Comp 9-13-22.pdf
(827.68 KiB) Downloaded 211 times
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Rich Gorski
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Re: Successful neutron emission from new fusor

Post by Rich Gorski »

test
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Rich Gorski
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Re: Successful neutron emission from new fusor

Post by Rich Gorski »

Sorry, here's the star mode image.
fusion-demo-9-13-22_M2.jpg
JoeBallantyne
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Re: Successful neutron emission from new fusor

Post by JoeBallantyne »

Hi Rich -

Good report. I am curious what bias voltage you set on the GE B10 tube? I have several of those tubes, and if you don't turn the bias voltage down to about 700-730V, they detect gamma rays and beta particles, not just neutrons. They basically act exactly like a big sensitive gieger counter. Which is NOT what you want when you are trying to detect neutrons.

Did you adjust the voltage on the Ludlum 3?

If not, it was probably about 900V, which means you were counting a lot more than just neutrons.

Joe.
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Re: Successful neutron emission from new fusor

Post by JoeBallantyne »

In fact getting the voltage set correctly for those tubes is difficult if you don't have a neutron source. (Its actually pretty tough even WITH a neutron source, as in my experience you have a 5-10V window around about 710-720 volts where the tube will detect neutrons, but is pretty insensitive to gammas and betas.) Go above that, and the counts just go through the roof. The exact voltage for detecting neutrons only depends on the particular tube. You can't just set it and think it will work for all of the tubes. Every tube is different and you have to set the voltage exactly for that tube.

Joe.
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Re: Successful neutron emission from new fusor

Post by JoeBallantyne »

I didn't notice anywhere in your report where you discuss setting the bias voltage on the tube.

Hence the questions.

Joe.
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Rich Gorski
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Re: Successful neutron emission from new fusor

Post by Rich Gorski »

Hi Joe,

Thanks for the quick reply. Yes, I'm aware of the neutron sensing calibration issue. That's why I called this a crude calibration having no access to a calibrated unit or a known neutron source. I have the bias set on the ludlam M3 at 750V based on info from current model GE tube specs that show operation between 700 and 800 volts. Note also in my report that I have tested the fusor with hydrogen at the same 37kV voltage, 20 mA current and the B10 tube showed only background counts while my CdTe detector was showing high levels of gammas at the same time. I did this to prove to myself that I was indeed detecting neutrons and not gammas. I was also concerned that this could be a RF issue even with shielded cables but again the H2 test should have shown that up. So, although the calibration could be off my belief is that these are indeed neutrons.

Rich
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Re: Successful neutron emission from new fusor

Post by JoeBallantyne »

You indicated that you used a Ludlum Model 3 to drive the GE B10, but your output you show as a voltage level on a digital Rigol scope.

The model 3 that I am familiar with, has no output on it anywhere to connect to a scope.

How did you get the scope trace you are showing in your doc?

Joe.
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Rich Gorski
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Re: Successful neutron emission from new fusor

Post by Rich Gorski »

Hi Joe,

I modified the Ludlam M3 by creating a direct connection from the M3's analog meter to the Rigol scope. This is a cheap way of monitoring the M3 output on the scope over time. The 1M ohm scope impedance should have no significant effect on the M3 operation.

In relation to the gamma issue I also have the entire B10 tube and HDPE moderator encased in 1/8" lead sheet. So very few if any X-rays should be able to trigger it. Only the neutrons can penetrate.

Rich
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Richard Hull
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Re: Successful neutron emission from new fusor

Post by Richard Hull »

I second Joe query on the boron lined tube. I have for years noted that it is nothing more than a GM tube unless hyper critically biased. Often far too sensitive to as little a a +/-20 volt swing from the ideal neutron detection bias.

I suggest you fight for the silver activation end of your effort which on the surface of it seems good. At 37kv silver activation is possible to a 4X or better degree over background.

Your setup looks good and I would be tempted to put you in the neutron club. Can we get more data like the pressure you operated the fusor deuterium level? Are you planning on continued operation of this system in future?

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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Rich Gorski
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Re: Successful neutron emission from new fusor

Post by Rich Gorski »

Richard,

Thanks for your input. The fusor deuterium level was 15mTorr running at 37kV voltage and 20mA current. Under this condition the Ludlam/B10 max rate showed 4600 CPM with the ludlam bias at 750V. When I ran the fusor with hydrogen under the same electrical conditions the count vanished to background (near zero). So it appears that the B10 tube was not acting as a GM tube else the gammas produced with hydrogen would have triggered the B10 tube as with deuterium. Also note that the B10 tube was shielded by 1/8" lead sheet. So if these were not neutrons what was the B10 tube detecting through 1/8" of lead and only with deuterium?

At the moment the fuser is partially disassembled. I'm planning to add anode layer ion sources to a new device in the near future.

Thanks,
Rich G.
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Re: Successful neutron emission from new fusor

Post by JoeBallantyne »

I like the fact that you did one run with deuterium and one run with hydrogen and showed the difference in the neutron counts.

Based on your report, I would agree you are making neutrons.

I'm a little concerned about the shape of the graph you showed for the activation measurement, as it doesn't really show clear exponential decay across the whole Rigol trace. There are two peaks followed by decay on the LHS of the the Rigol trace. But the second peak is almost as high as the first one. Which is not what you would expect from an exponential decay curve. It seems like the noise level must be almost as high, or higher than any signal you are getting.

You would probably get a significantly stronger activation signal if you could reduce the time it takes to go from irradiating to measuring. 40 seconds is quite a long time. Perhaps when you reassemble your fusor, you can make it easier to get your sample from your neutron oven to your counter.

Joe.
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Re: Successful neutron emission from new fusor

Post by JoeBallantyne »

I'm a little jealous of your power supply. :-) Being able to pump in 50mA at 60kV means you pretty much have to worry about melting your cathode long before you have to worry about your power supply shutting down because of excess current.

Let me tell you, dealing with a power supply that decides to turn off every time it hits 8.5mA is not a whole lot of fun.

Joe.
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Richard Hull
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Re: Successful neutron emission from new fusor

Post by Richard Hull »

I am personally familiar with Joe's shutdown plight. When I was working with VCU and their fusor. They had top drawer brand new kit on hand with a professional current limited 40kv Spellman at 8ma. About the time we would get to the point to making their new 3He tube hooked to brand new NIM cage start to sing, the *%$&&@@! supply would kick out. Frustration was the king of the moment. Fusion, when done, was fleeting and hard to control with no backup current available.

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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Rich Gorski
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Re: Successful neutron emission from new fusor

Post by Rich Gorski »

Joe & Richard,

Thanks for the acknowledgement that we have generated fusion neutrons. Yes, I've been well frustrated by the current limit/shutdown feature of the DXR3000 power supply. So I've got the current limit set at the 50mA maximum. Its an intricate dance between the supply voltage and gas pressure to get the fusor into the nice star mode. Eventually, as I let the fusor run it will settle down at a relatively good pressure/voltage point where fusion events happen. That power 3KW supply is a dangerous beast. If I'm not paying enough attention the grid rings can quickly glow red hot and then of course the gas pressure rises which increases the current and then shut down occurs.

I agree that the silver activation test only gave a small questionable indication of activation but it did initially (after 45 seconds) show a level 2.5X above background. But, yeah, I was hoping for a larger signal. When the unit is operating again I will repeat the test hopefully with better results.

As I mentioned, the fusor is being redesigned into a new form with ion sources and a unique beam focus and accelerating structure (no wire cage). I will soon post some info with photos of the anode layer ion sources I have been developing. Question... can I post videos on fusor.net? I have a few videos of a sheet hydrogen ion beam going in and out of focus as the focus voltage changes. Maybe I will post that in the near future.

Thanks,
Rich G.
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Rich Gorski
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Re: Successful neutron emission from new fusor

Post by Rich Gorski »

Interesting fact about neutrons (free) that have been liberated from the nucleus.

Free neutrons have a short half life of only about 10 - 14 minutes. They decay into a proton, an electron and an anti electron neutrino. The anti-neutrino is required to conserve lepton number ???. Cool !

Rich G.
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Re: Successful neutron emission from new fusor

Post by Richard Hull »

Smart folks would dwell and consider much due to the above fact. There is much to ponder in the apparent infinite lifetime of the neutron within a nucleus and how there is no need for a strong force until a second proton is added to matter, (Helium 3), and no second proton can be added until one neutron is present, (deuterium). Other than Helium 3, no stable atom can exist with more protons than neutrons.

Think long and think deep. "Read not to accept and take for granted, but to weigh and consider."

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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Rich Gorski
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Re: Successful neutron emission from new fusor

Post by Rich Gorski »

Neutrons, protons and the strong nuclear force...
As I ponder deep into the last post one comes to ask the question, "what holds the 3 quarks together in a proton considering all that charge in such a infinitesimally small volume?" The answer I think is again the strong nuclear force mediated by the force carrying particle called the gluon. Is this the same force that bind protons and neutrons together in the nucleus of an atom and does that mean gluons are the force carrying particle between nucleons?

Rich G.
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Liam David
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Re: Successful neutron emission from new fusor

Post by Liam David »

I could be wrong and I have not taken graduate-level classes in QCD, but I'm pretty sure that the strong nuclear force acts to keep the deuteron together. Even though there is no classical electrical repulsion between a proton and a neutron, they must still exchange momentum to be considered bound (e.g. if the proton is dragged by an electric field, the neutron moves with it). Within a nucleon, the strong force is communicated via virtual gluons (which themselves carry color charge and thus cause the color charge to "rotate" between the different quarks, loosely speaking). This is called the "strong force." Between nucleons, gluons can't travel without violating the color neutrality of the baryons. Mesons mediate the momentum exchange instead. This is called the "strong nuclear force." The mesons have mass and via the uncertainly principle cannot exist for very long, and so the interaction has a very short range. See e.g. http://webhome.phy.duke.edu/~kolena/mod ... s.html#005 or https://en.wikipedia.org/wiki/Strong_interaction.
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