Fusor Progress

[taylorw]

Hey Guys,

Well I have finally made a start for a go at a Fusor. I am converting a Varian Stable Isotope Mass Spectrometer to a small fusor.

We are currently about to temporarily move from Arkansas to Nevada, so its a bit hectic around here. I have disassembled and reassembled it partially so the useable parts can be taken with us. I think I am going to hold off on any further major construction until the move is complete, though I may do some. How this project progresses is not really set in stone, as it is kind of a side project, though I hope to put a lot of effort into during the next few months

You can see more on the efforts, as to what I have done and am doing, on the laboratory page of my website (http://sciradioactive.googlepages.com/). It originally had 2 diffusion pumps, but I am only using one. The vacuum pumping (Diff Pump etc.) is in pretty good shape. You can see one of the diffusion pumps, I think, in one of the pictures, the roughing pump and system is below, it's ISO to the Diffusion Pump, but from there it is all conflat . You can see the original system in a link on that page. I need a couple of things including a good feedthough, but it is a pretty good system. The main conflats you see are I think 4 1/2 inch, though I may use reducers to bring it down to a smaller size. There won't be a viewport, but this is a machine not something to look at fancy colors;-)

Thanks so much!,
--
- Taylor Wilson

7/35- I added pictures and captions here so you didn't have to link to my website

1st Picture- the original Mass Spectrometer

2nd Picture- The fully disassembled spectrometer. Magnet, target, sample inlet and associated equipment, and second diffusion pump has been removed. The middle conflat port is for the vacuum gauge seen below on the platform

3rd Picture- The chamber where the Fusor will be, I decided against putting it directly above the diffusion pump inlet. It's not just a huge chamber diameter wise, bit the addition of a piece from the original beamline gives it alot of depth.

[MarkS]

View ports are a critical feature. While qualitative, they do let the user know key changes in the plasma, and can let you know if something goes wrong, ie grid melting.

Good Luck!

[taylorw]

Thanks Mark,

For the first runs I probably won't have a viewport, but later on I will probably put in a mirror (anyone see any problems with having a mirror in there not radiation or anything related since it will not be directy in the fusor chamber, but I'm thinking from the vacuum pump, etc. Does any one have a system with a mirror in the chamber, under vacuum?) so I can have a reflected viewport. I won't push it too hard without one and open it up somewhat regularly to fine tune it and check for damage to the grid.

Thanks,
- Taylor

[taylorw]

I have removed the chamber and associated equipment from the spectrometer for packing. The roughing pump system got a little scambled up during it trip to my current lab so I may take the pieces to my new lab and start from scratch on it.

I have posted pictures of the the removed vacuum system, diffusion pump, and roughing pumps.
Thanks,
- Taylor

[taylorw]

Hey guys,

Well it’s been a while since I have had anything to say about my project so I thought I would post a picture of a new chamber I have acquired. I was told that I need a viewport of some kind and I went over the top! It is fairly large and has a large viewport on the bottom along with one I have put on one of the ports on the side. It will be "interesting" to say the least to shield the x-rays shining out of the big one:-). It has 4 ports around the chamber that will be good for ion guns and one is where I will place the feedthough. It even has water cooling for going to higher wattage! Along with this another change is that I am going to use an ion pump that is enclosed as a full system with foreline pumping, etc.

The following should probably go in the radiation forum, but I really don’t want to break the thread up.

All of these things are surplus I have gotten from the University of Nevada, Reno. I have gotten a lot of rad detection equipment too and along with some more BF3 and He3 tubes, I have also gotten a neutron ionization chamber, something that I am not familiar with. I will give details if wanting on gas fill, etc., but I was wondering if anyone else had used one. On the subject of neutron detectors, I took some of my neutron detectors up to the university to check them out with a Cf-252 source. I have a couple of B-10 tubes that I run with about 700 volts and they were surprisingly reactive to the source considering they are supposed to be the least sensitive of the bunch.

Thanks so much,
- Taylor

[Richard Hull]

Really, really, sweet. Nice stuff, as a friend of mine used to say. That is a fine looking system base that you have there. We look forward to future reports.

The B-10 tubes are subject to Gamma's and other radiations that a well done BF3 or He3 are insensitive to. While they are OK, I settled on the extremely reliable He3 tube. It demands a careful setup by a knowledgable user with some electronic gear and the right amps and windowing electronics. Once steup, it is just the best.

Richard Hull

[Carl Willis]

Hi Taylor,

Congrats on your good surplus pickups. That's nice ConFlat stuff there.

The low-voltage boron-lined tubes (I think that's what you have) are indeed quite sensitive to neutrons, even if they lack some desirable discrimination against gamma rays. You'll want to use the Cf source to set up these tubes carefully to maximize the neutron response relative to the gamma response. Richard, Brian McDermott, and I have all used the B-lined tubes. There are a couple posts I made that discuss how to set them up.

I look forward to seeing more from you, now that you've got good new surplus stuff. Maybe UN-Reno will give you a corner of lab space to work in?

-Carl

[taylorw]

Richard-

Yes I know the B-10 lined tubes are very problematically sensitive to gammas, but with a hot source near on the right voltage it didn't affect the count! They are interesting tubes for many particular circumstances I can think of, but for neutron metrology for my fusion systems I am not going to use them, at least not the back bone of my system. For that I will use He3, Bubble, and maybe BF3 tubes.

I was wanting to see if anybody has worked with a neutron ionization chamber before, but I will start a new thread in the rad forum. I will post a picture too.

Thanks!,
- Taylor