Fusion Claim - Luke Harrill

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Luke Harrill
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Fusion Claim - Luke Harrill

Post by Luke Harrill »

Good afternoon everyone. It's finally time to present this long awaited milestone, and also receive some critical peer-review. I'm going to be using data from Run #5 on 2021-12-03 since activation was pretty clean and I only had 2ish hiccups.

Neutron Detector Setup

For this run I was using a He3 tube with my paraffin moderator (discussed in viewtopic.php?f=18&t=12332&start=20 ). This was centered to the grid, and midpoint-to-midpoint is 37.16cm away. I have it biased by an Ortec 459 at 1.6kv currently (ferrites at both output and input). The preamp is a Cremat CR-110, and this runs into an Ortec 571 shaping amp (50ohm terminator at amp, and ferrites on both ends). At the moment I have it set to a gain of x20, shaping of 1usec. The amp's output is then run into a Ludlum 2221 scaler/ratemeter. The bias is turned off, it is 50ohm terminated at the meter, and the threshold is set to 14.5 mV. I set this up with some hot uranium ore following Carl's videos. Afterwards, I double checked everything on the oscilloscope to make sure that I wasn't getting any surprises. I left the threshold a little high for the moment. At these settings, a 20min average on background is 6.7cpm in Knoxville, TN.

The Ludlum 2221 is really useful. It serves as an analogue ratemeter, digital ratemeter, and can do timed counts. I generally leave the audio on 1click/10counts. When recording data for my runs, I write down the digital rate (on slow response).

Here's where I have an issue. I don't currently have the datasheet for my tube. I do, however, have a close reference. I think Richard's Reuter-Stokes is of similar active area (1"x22"), and has a sensitivity of 54 cps/nv for thermal neutrons. Maybe someone here has the specs for the Texlium Special?

If I use Richard's number as my first major assumption, I must still make a few more. Second, is that my paraffin moderator doesn't have many voids from cooling shrinkage (I topped it off as it cooled). Third, is that my inner PVC pipe isn't shielding the thermal neutrons (as discussed here: viewtopic.php?f=13&t=5691&start=10 ). I'll probably remove it soon. Finally, I am assuming that my window is perfect. (It's probably a little tight.)

With all of those assumptions, my measured and marked distance is 37.16cm. This will yield a TIER correction factor of ~5.355 with my current setup.

Neutron Oven and Activation Setup

My oven is made from HPDE, and has 1.9" in front of the sample, 3.0" behind the sample, and 2" or 2.8" (up/down, side/side) along the radius of the sample. I just was using the material on hand, and that's how it turned out. The center is 15.56cm away from the midpoint.

For this run, I was using a Ludlum 3 with a 4-49 pancake. It was set to the x0.1 scale initially, but I had to quickly turn it to the x1, then later to the x0.1 again. This ratemeter was on the slow response, which means it will go from 10% to 90% of full scale in 22 seconds.
Setup1_Edit1.jpg
Run Information

My general procedure is to lay my phone on the leaded glass and video the grid. This allows me to see in the chamber easier and use the timestamps for reference. The voltage, current, pressure, and count rate are currently logged by hand (in that order) as quickly as possible.

For Run#5 I was also trying to pin down a sparking issue, hence having the feedthrough shield removed, and the lead around the setup. I ran for ~2min, then took a ~2min break to check it out. After that, I restarted the system and quickly ramped up to power (plasma image pt.1). Somewhere I tripped one leg of the thermal relay, but quickly brought it up to power again.

The TC gauge was reading ~7mTorr and I was mostly between 48-49kv. For current, I was running around 10mA at the end. See attached data.
2021-12-03_Run5_Plasma1_Edit3.png
2021-12-3_Run5_Data2_Edit1.png
Post Run

After I shut Fusor-V2 off, I moved my silver sample to the Ludlum, scaled up, and a friend snapped a photo at 1,200CPM, while I snagged my phone and sat it on the meter. When I scaled down, I lost a lot of time waiting for the meter to rise back up (it was on slow). Afterwards, I went back and logged the time/rate by the video. I don't have a timestamp for the photo at 1,200CPM, however my phone was in place at the 1,000CPM mark.
Activation_Edit1.jpg
Numbers based on the He3 tube alone would suggest a TIER of over 150k n/sec. Perhaps more, depending on the the information mentioned earlier. I eagerly await all of your critiques. Note: As per the rules, I still need to get a photo of myself with Fusor-V2.

-Luke Harrill
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Richard Hull
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Re: Fusion Claim - Luke Harrill

Post by Richard Hull »

Luke,

You not only made the neutron club but the elite fusioneer ranking. (note: this is where you will be mentioned and not the neutron club as noted). A great and full featured report.

We would like to see an image of you standing by your fusor system.

Welcome to the fusioneers on this group. You have worked on this for over 4 years that I know of.

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: Fusion Claim - Luke Harrill

Post by Joe Gayo »

Luke,

Great setup/run.

Question: Did you remove the He3 tube during the run?

The other thing, I don't quite understand is that the Cremat CR-110 has a gain of 1.4V/pC, and then you run that through the shaping amp at 20x, it would seem the discrimination threshold should be much higher to avoid pulse pile-up from x-rays.

I'm not questioning whether or not you have neutrons - I just providing feedback.

Joe
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Richard Hull
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Re: Fusion Claim - Luke Harrill

Post by Richard Hull »

Joe is spot on! It is always cool to have your fusor running and pull out the 3He tube. If all is set right the counter should dummy up. It is the ultimate test to see if your discrimination is good. As Joe notes, your silver activation is proof positive and will always be the gold standard, regardless of any electronic detection issues.

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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Jim Kovalchick
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Re: Fusion Claim - Luke Harrill

Post by Jim Kovalchick »

Congrats Luke!
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Aidan_Roy
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Re: Fusion Claim - Luke Harrill

Post by Aidan_Roy »

Luke,

Great job! Your set up looks very clean and I am jealous of the monster power supply you got. I agree with Joe that you need a bit higher discrimination level, especially if you climb into much higher voltages. Sounds like you really went all out on fighting noise too, once you get the discrimination set I doubt there will be any major issues contesting your results.

Aidan
Luke Harrill
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Re: Fusion Claim - Luke Harrill

Post by Luke Harrill »

Hello Everyone, I greatly appreciate the feedback and complements! Thank you all.

Unfortunately I didn't have a chance to remove the moderator during that run.

I also completely forgot to add in the x0.1 multiplier on the Ortec 571. Internally, this unit has a jumper to multiply everything by either x1 or x0.1. It is set to the latter, because I was concerned about blowing the 2221's front end. This puts it at an overall gain of x2. Big difference.

Checking with the scope, the stronger peaks from background are ~90mV. After the main amp, the highest peaks looked to be around 140mV.

New Changes

Since that run, I have made several changes. I removed the inner PVC pipe and wrapped the tube with cardboard in 3 small spots to keep it centered. The wax was pretty solid and the tube was well centered also. Next I mounted the moderator with pipe clamps. This changed the distance slightly, but I accounted for that. Finally, I reset the threshold by extended counting time, instead of just a little above gamma detection. (Also used a hotter setup.)
neutron1.3.jpg
I had left the shaping low to start off with, but 2usec seemed to work better today. I finally went with x2 gain, 2usec, and a threshold of 30.0 mV. Here's what I came up with.
Background1.png
Background1.png (79.05 KiB) Viewed 2773 times
Run Testing

After doing all of that, I had some interesting results. I removed the moderator, and the background was still elevated. After removing the nearby oven, the counts decreased more. I proceeded to move both of them away even further. When I walked back to where I was operating, the rate increased a little. I stepped over to the frame, and saw yet another increase... heh. I'm a moderator too. (Fast neutron Q-value makes a lot of sense.)

So needless to say, the detector hasn't completely stopped counting at these rates, but it is decreasing greatly. Here's where I'm currently at. Does that look more inline with everyone else's setup?
2021-12-10_Run2_2.png
-Luke Harrill
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Richard Hull
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Re: Fusion Claim - Luke Harrill

Post by Richard Hull »

To my eye, it seems like you are perfectly functional on the neutron counter. It is important to remember that cosmic rays can hit the SS 3He tube and cause a pulse. in or out of moderator. When set properly you might normally expect no difference or very little, in or out of moderator as a background. Your electronic neutron detection system is setup properly now, I believe.

I get about 6-10 cpm in moderator as a background. Depends on the solar activity. You and I have the same size P4 tube so you seem good. With that long P4 tube in a good moderator that you obtained from me at HEAS a couple of years ago, and now that it is setup properly, you have one of the most sensitive neutron counters that one could want.

For all reading this..........Again, if you are activating silver and just using a GM counter you are doing fusion regardless of any more fancy electronics.

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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