Progress Update

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Joe Gayo
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Progress Update

Post by Joe Gayo »

I haven't posted an update regarding my cube device for some time, and I wanted to share what I've been working on in the lab.

I'll post a video and annotated still image here.
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Joe Gayo
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Re: Progress Update

Post by Joe Gayo »

Here is the video: https://youtu.be/hMA_C7lK9MU

A - Custom High Voltage Feedthrough, loosely based on Liam David's design, tested to 100kV
B - 85kV @ 1.67mA
C - Chamber Pressure (Torr)
D - Ion Source Pressure (Torr)
E - Ion Source Current (mA)
F - 5999, 6-second count (the previous cube would read 1800 in the same period for the same voltage/current)

Chamber is water cooled.
19 Dec 20 - Annotated.png
JoeBallantyne
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Re: Progress Update

Post by JoeBallantyne »

So what is your estimated total neutron ouput per second for this run?

That very large neutron tube looks like one of a pair of tubes Jon Rosenstiel was using to detect neutrons generated from high energy cosmic rays a few years back.

Joe.
Last edited by JoeBallantyne on Sun Dec 20, 2020 3:44 pm, edited 1 time in total.
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Joe Gayo
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Re: Progress Update

Post by Joe Gayo »

The tube is 61 cm away so that reduces the count and x-ray influence. The ion current from the sources is minimal, so the n/s/mA is very good.

The setup easily activates indium.
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Richard Hull
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Re: Progress Update

Post by Richard Hull »

Great setup Joe! I have a large BF3 tube like the one you show.. I assume it is BF3?? they are not very sensitive to even intense gamma or x-ray fields if biased properly. Both BF3 and 3He are tremendously gamma ray blind often up to a few roentgens!! BF3 tubes typically never have even one atmosphere in them while 3He tubes typically have at least 3 atm but there are 4 and 5 atm tubes available if you have the money. BF3 tubes all take more bias in working mode than 3He tubes. Again, bravo on a great working system.

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: Progress Update

Post by Jim Kovalchick »

Joe,
Thanks for sharing. Yours is certainly a premium, benchmarkable setup. Do you use any shielding?

Jim K
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Joe Gayo
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Re: Progress Update

Post by Joe Gayo »

@Richard

I've experienced problems with pulse pileup with 100kV @ 10mA in an aluminum cube. The distance is an additional measure of system integrity on top of discrimination and correct biasing.

What's the cps/nv for your large BF3 tube?

@Jim

All of my runs are controlled remotely using a custom IDE/Arduino from about 35ft away. The operator station also has sheet of lead creating a shadow. Even still at 100kV and 5mA, my Miron x-ray/gamma dosimeter shows an above background dose.
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Joe Gayo
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Re: Progress Update

Post by Joe Gayo »

Some calibration runs.

80kV, 180uA ion current, 2.3E+6 n/sec, 56k cpm
100kV, 190uA ion current, 3.9E+6 n/sec, 95k cpm (*Corrected Typo, previously 4.9E+6*)

On a fun note: There is detectable fusion at 10kV, 50uA
Last edited by Joe Gayo on Mon Dec 21, 2020 1:06 am, edited 1 time in total.
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Richard Hull
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Re: Progress Update

Post by Richard Hull »

I bought the big BF3 in 2000. biased it properly using a neutron source to prove to myself it was good. Them got two 3He tubes and put the BF3 away forever. It is still up in the attic of the lab and has never seen D-D fusion nor will it even, most likely. I keep it just because it works and I want to save it for a future effort somewhere, sometime, maybe, I hope. Wish I could give you more data on it in relation to D-D fusion.

You are doing great with your ion source in that cube!

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: Progress Update

Post by JoeBallantyne »

For your two calibration runs, the ratios between the cpm and the total neutrons emitted per second are different.

Based on the first run, the expected total n/sec for the second run would be 3.9E+6. (95kcpm / 56kcpm) * 2.3E+6 n/sec = 3.9E+6 n/sec

Or is the relationship between cpm and n/sec not linear? (I would assume you use the same formula for deriving total n/sec for both runs, based directly on the CPM. Since the detector size/geometry/configuration does not change between runs.)

Also it seems you have 2 currents of interest in your setup. One is the ion source current which is down in the hundreds of microamps range, and the other is the cathode current which appears to be in the 1-2mA range.

Is that right?

That means you have another whole control parameter to play with for optimizing things. (ion source current)

You have a VERY nice setup.

Joe.
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Joe Gayo
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Re: Progress Update

Post by Joe Gayo »

Good catch, it was a typo. The post is now corrected. However, the ion source was misaligned for both of the two calibration runs. Taking new data now, and WOW! I'll post results soon.

The cathode current is a function of the ion current. It's higher than the ion source current because of secondary electron emission. There is no gas discharge in the main chamber. The camera looking through the viewport just sees a faint blue glow from electrons hitting the glass feedthrough. (And speckles from x-rays of course)

Thanks.
Last edited by Joe Gayo on Mon Dec 21, 2020 4:20 am, edited 1 time in total.
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Joe Gayo
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Re: Progress Update

Post by Joe Gayo »

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Re: Progress Update

Post by Joe Gayo »

85kV, 180uA, 261k CPM!
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Joe Gayo
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Re: Progress Update

Post by Joe Gayo »

90kV, 190uA, 292k CPM!!
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Re: Progress Update

Post by JoeBallantyne »

1.2E+7 n/sec (your last run) is doing VERY well indeed.

What pressure are you running at? If there is no plasma glow at all, I expect you are running at much lower pressures than pretty much everyone else here.

Joe.
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Richard Hull
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Re: Progress Update

Post by Richard Hull »

Once the voltages get high, the current becomes much less. This is seen in all the mid sixties Farnsworth effort with the cave fusor. Lower pressures 2 microns and just a few hundreds of microamps to 2 ma max. I refer to this as "clean operation". Rarely seen in amateur work. Still, there is always a limit that keeps the fusor either simple or complex from significant return on invested energy.

Joe, Thanks for the tube info. I will have pull my tube out of storage and photograph it. Most BF3 tubes are at 76cm or 1atm with a less than 1atm fill of BF3 and the remainder a backfill of argon.

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: Progress Update

Post by Mark Rowley »

Joe, I noticed similar results when I operated between 50-67kV. When wall loading was optimal all I needed was 1.5 to 2mA to get some really nice numbers.

67kV was my ceiling. Doubtful I’ll be able to get beyond that anytime soon.

Mark Rowley
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Joe Gayo
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Re: Progress Update

Post by Joe Gayo »

The chamber pressure is 1.5E-5 Torr typically during operation.

Just as a interesting side note, the results were seen immediately and no wall loading or "conditioning" was required.

I will be installing my 125kV power supply in the next few weeks. In addition, I have about a factor of 10 in ion current left to increase.

I would like to be the first amateur to reach 1E+8 n/sec.
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Scott Moroch
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Re: Progress Update

Post by Scott Moroch »

Joe,

Very nice setup. What type of ion source are you using?

Thanks!

-Scott
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Jon Rosenstiel
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Re: Progress Update

Post by Jon Rosenstiel »

Joe,

Love your setup, and your hv-feedthrough. Guess I'm going to have to go that route too. Keep up the good work.
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Joe Gayo
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Re: Progress Update

Post by Joe Gayo »

@Scott

The ion source is a simple discharge source that's been cobbled together, nothing special

@Jon

Thanks. Nice work on the Co-60!
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Joe Gayo
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Re: Progress Update

Post by Joe Gayo »

Operational tuning (pressure, etc.) has resulted in a dramatic improvement. 100kV, 200uA ion, 2.5 mA cathode, 2 E-5 Torr, 654359 CPM
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Richard Hull
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Re: Progress Update

Post by Richard Hull »

Great Joe! You are the first to report 100kv results. X-rays gotta' be a killer....Thank goodness the current is low.
I promised an image of my BF3 tube and here it is. the lab was at 33 deg F.

Richard Hull
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3He - BF3 Anno.jpg
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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