Fusor Update / Improved Numbers

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Mark Rowley
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Fusor Update / Improved Numbers

Post by Mark Rowley »

After some needed adjustments, here is my latest run.

30kV (60kV precipitator supply)
2.0mA
35mTorr deuterium
Average 1100cpm/neutrons (SNM-14 corona tube) during a 10 minute run. At one point it floated above 1200 but the average was a stable 1100. Prior count record was 300cpm/n.

I can only guess how much higher these numbers would be if detection was done with a decent He3 tube. I’m having difficulty finding the math relevant to an SNM-14 to determine my total neutron output. It’s becoming painfully apparent I’m going to have to fork out the dough for a BTI purchase. That way I can calibrate the 14 and then use the BTI’s for pulse work.

Improvements were made with gas collection from the PEM cell. I discovered a flaw in my previous collection method which allowed for some air to mix within. Since rectified.

Neutron detector and moderator placed horizontal to the rear of the fusor. Noted much better detection efficiency.

Added more lead shielding.

Precipitator supply seems to be working like a champ and I’ll keep pushing it as far as my kV meter will permit.

I think it’s possible I may achieve 2000 or more cpm before kV gauge maxs out at 35kV. I’ll see what I can do in the next few days.

I’m also noticing how much difference just a little extra gas flow can make. As stated, learning to drive these units is just as formidable as the build.

Mark Rowley
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Richard Hull
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Re: Fusor Update / Improved Numbers

Post by Richard Hull »

Yes, operational skills develop only after the build and an adroit hand develops first in stabilizing a system and later, observing what results from adding extra gas, extra voltage and current can have. With each run the skills improve once some sense of stability in operation are in hand. In spite of the inelegance of the fusor's manner of doing fusion, extreme elegance in operational artifice is demanded to make it shine in performance.

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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Mark Rowley
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Re: Fusor Update / Improved Numbers

Post by Mark Rowley »

Quick YouTube video of my latest run. 29kV / 2.4ma / 39mTorr deuterium. Average was ~1350cpm/n with a brief peak at 1456cpm/n.

I was able to bump the numbers a bit higher (approx 200cpm more) by increasing the deuterium flow rate. I don’t like this particular method as it seems wasteful with the deuterium.

If I can manage to keep a plasma lit at 30mTorr or below, I think I can substantially increase performance. Still learning how to carefully manipulate the system.

Considering I was barely detecting over 150cpm/n last month, I think things are moving along well. And now that the numbers are better, I’m going to try some CR39 neutron detection soon. Pending good results, this should pave the way for some upcoming linear pinch pulse shots.

https://youtu.be/NCeZcXsAJxs

Mark Rowley
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Mark Rowley
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Re: Fusor Update / Improved Numbers

Post by Mark Rowley »

Latest fusor run with the 60kV precipitator....

28kV
4.3mA
48mTorr deuterium

~3100 cpm/n (average of 5 one minute runs)
Peak at 3331 cpm/n

Ludlum 2221 Ratemeter
CHM14 BF3 Neutron Detector 7" from the poissor
Paraffin moderator
1-2cpm background

Contrary to my last post, today I found that increasing deuterium pressure and running at a higher current made a significant difference. I still have about 50% range left in the voltage control to push this farther. Unfortunately my fusor runs are limited to the amount of deuterium I produce beforehand with the PEM cell. Being the case, experimentation often times gets cut short.

It'll be interesting to see what the ultimate ceiling will be with this 60 and later the 30.

Mark Rowley
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Richard Hull
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Re: Fusor Update / Improved Numbers

Post by Richard Hull »

The lawson criteria in action.....Talked about forever here. More fusion fuel, (deuterium-pressure) + more deuterons created, (current increased) + greater energy of the deuterons, (increased voltage and probability of fusion) = More fusion.

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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Mark Rowley
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Re: Fusor Update / Improved Numbers

Post by Mark Rowley »

Rex Allers has been helping me with a mod to increase the power output from the 60kV precipitator power supply. It was somewhat difficult as the current limiter function was controlled by the unidentified 16 pin IC. Ultimately I decided to attempt an "educated guess" and it worked. As long as I keep the output at 10mA or below I think the supply will survive. I've already made several hour long runs at 5mA with no issue and with the mod, I now have even higher current capabilities. From what I can tell, I'm only about 60% deep into the voltage control range.

-Results-
Last night I achieved a stable ~12,000 cpm neutron rate with my Ludlum 2221 / SNM-11 BF3 tube arrangement. The tube is 7" from the poissor and I have it surrounded with 4 inches of paraffin moderator. The SMN-11 is shown to have a thermal neutron sensitivity of 0.8. Using Steve Sessleman's calculator, this puts me in the 1 e6 n/s isotropic range. Being a 2.75" cross fusor, my operational conditions were around 6.2ma, ~34kV, and 30-33 mTorr of deuterium. Removing the SNM-11 from the moderator dropped the count down to about 2 to 5 cpm.

I know 1e6 n/s is quite a claim and tbh, I/m not ready to do so and I'm highly skeptical. Fiddling a bit with the numbers, even if I bumped the sensitivity to 1.2, I'm at almost 7e5 n/s. With the supply limitations I/m confident I could still hit the million n/s mark.

In the next day or two I'll make a YT video of this and post it to the thread.

I humbly submit this report and expect a ton of questions.

Mark Rowley
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Richard Hull
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Re: Fusor Update / Improved Numbers

Post by Richard Hull »

You did it correctly. Pulling the tube out of the moderator tells the tale.

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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