Archived - Typical fusor operation conditions- from activation experiment

Current images of fusor efforts, components, etc. Try to continuously update from your name, a current photo using edit function. Title post with your name once only. Change image and text as needed. See first posting for details.
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Carl Willis
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Archived - Typical fusor operation conditions- from activation experiment

Post by Carl Willis » Thu Feb 13, 2003 9:18 am

Here are some pictures that illustrate my fusor's operating conditions, and the experimental setup for activating manganese with it. PLEASE SEE the neutron / radiation detection forum for more details.

First Image: the data file showing pressure, voltage, current, neut counts vs. time. The values are hard to read off this plot, it's designed to show all four measurements simultaneously.

Second Image: A concentrated solution of manganese sulfate in a juice bottle is set up next to fusor, itself shrouded in some lead sheet and other stuff to keep cooling air and x-rays contained. The manganese bottle sits in a small tank of water for additional moderation.

Last Image: the manganese juice under an NaI(Tl) crystal being counted.

Apologies for the huge files...will be gone soon!
-Carl
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Re: Pics from activation experiment

Post by Carl Willis » Thu Feb 13, 2003 9:21 am

Here are the other pics (I hope)...
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Re: Pics from activation experiment

Post by Carl Willis » Thu Feb 13, 2003 9:22 am

Here's another one, showing the manganese juice ready for bombardment with neuts...
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Re: Archived - Typical fusor operation conditions- from activation experiment

Post by paulriley » Mon Apr 12, 2004 10:07 am

Any idea if the spikes are real or interference? If so what is interfering?
Is the cyclic pressure variation real?

Paul

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Re: Archived - Typical fusor operation conditions- from activation experiment

Post by pkuiper » Mon Apr 12, 2004 2:37 pm

Carl Willis wrote:
> Second Image: A concentrated solution of manganese sulfate in a juice
> bottle is set up next to fusor, itself shrouded in some lead sheet and other
> stuff to keep cooling air and x-rays contained. The manganese bottle sits
> in a small tank of water for additional moderation.
>
> Last Image: the manganese juice under an NaI(Tl) crystal being counted.

An alternative source of manganese would be batteries.
Ordinary carbon-zinc batteries or alkaline batteries will do, but there is also
manganese dioxide (brownstone, the black stuff) in lithium batteries.
http://micro.magnet.fsu.edu/electromag/ ... aline.html

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Re: Archived - Typical fusor operation conditions- from activation experiment

Post by Carl Willis » Mon Apr 12, 2004 4:02 pm

Hi Paul,

The spikes in the pressure signal are just noise. The pressure transducer was a Tylan General 10-torr capacitance manometer, and the noise had something to do with my first power supply for the manometer I think. A more recent power supply does not seem to have that problem.

Yes, the pressure fluctuations are real. The fusor was hand-controlled, the most important control being the manual vacuum line valve, which was used to adjust pressure since the input needle valve wasn't too precise. When I saw signs of thermionic runaway commencing, I'd open the vacuum valve more for a brief time to stabilize the system. That is why you see the pressure drops.

-Carl
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Re: Archived - Typical fusor operation conditions- from activation experiment

Post by Carl Willis » Mon Apr 12, 2004 8:38 pm

Hi Peter,

MnO2 works great for activation as well, see the Neutron Detection forum on 2003-04-17 for an activation experiment in which I used it rather than the sulfate. Richard Hull recommended Mn plate at that time, which of course would be ideal.

I'd be cautious about the purity of battery contents for an activation experiment. One can't be sure what all goes into the electrolyte, and there's likely to be a fair amount of neutron-hogging boron in battery graphite. When I was younger I went to great lengths to obtain useful chemicals from household supplies, mainly to support a fireworks habit that was not supported by the parental authorities. Since then, eBay has opened vast inroads for the small-time, no-questions-asked hustling of chemicals, mundane and hazardous alike. I think that's where I got my MnO2. The chemistry dep't at my college kindly donated the multiple kilograms of old MnSO4 I used.

That said, I still buy lithium batteries for the lithium (which would have to be HAZMAT shipped otherwise). One AA cell contains about a gram, as a foil sheet that can be extracted with care under mineral oil. Li-6 has a very high neutron capture cross-section. Lithium salicylate is perhaps the only known water-soluble neutron scintillator.

I look forward to having another activating fusor up and running.
-Carl
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Re: Archived - Typical fusor operation conditions- from activation experiment

Post by pkuiper » Mon Apr 26, 2004 6:23 pm

Carl Willis wrote:
> I'd be cautious about the purity of battery contents for an activation
> experiment. One can't be sure what all goes into the electrolyte, and
> there's likely to be a fair amount of neutron-hogging boron in battery
> graphite.

I now did the experiment with ordinary 1.5 V batteries. They fit nicely in the
channels in the moderator around our Radium-Beryllium source (flux about
100 neutrons per cm2 per second). Measurements with a 3"x3" NaI
scintillator are shown at http://w3.msi.vxu.se/~pku/FyC701/Mn56.html .

There is not much else besides manganese that is activated, although it
seems there is something on the high energy slope of the K-40 peak. It
seems to have a long half life. I will try to find out if it really is something.

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Re: Archived - Typical fusor operation conditions- from activation experiment

Post by Carl Willis » Thu Apr 29, 2004 4:14 am

Hi Peter,

That's a nice toasty RaBe, and I wish I had one! How many curies? Who owns it?

Certainly that's a good activation experiment you did.

-Carl
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Re: Archived - Typical fusor operation conditions- from activation experiment

Post by pkuiper » Thu Apr 29, 2004 10:56 am

Hi Carl,

There is 3 milligrams of radium in our Leybold neutron source. A local
highschool gave it to us (physics at Vaxjo University) because they wanted
to get rid of it. When we talked about it to the Swedish radiation-protection
authority, they were happy to know its location again. But we have to pay an
annual licensing fee now.

This group is stimulating me to try some new things with it. I get bored with all
those lab reports about activating our indium sample. I have a piece of
dysprosium. Just need to saw it so that it will fit in the channels in the
moderator. That seems to be a promising candidate for activation, but maybe
less appealing than activating a common household battery.

/Pieter

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