Fusor Repair

For posts specifically relating to fusor design, construction, and operation.
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Dennis P Brown
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Real name: Dennis P Brown
Location: Glen Arm, MD

Fusor Repair

Post by Dennis P Brown » Wed Dec 06, 2017 10:11 pm

As I mentioned under the neutron detector thread, my fusor's cathode had issues causing shorting across the support structure (via metal that had deposited upon the glass surface by the exposed section of the rod (being sputtered) that holds the cathode.)

I obtained a new diamond band saw blade for my glass saw to cut the glass cylinder pieces to the correct length that my electrode required to shield/insulate the exposed metal section of the cathode - note that one of the glass shields is just a std chemical beaker that I cut off the base.

These short glass shielding cylinders surround the cathode and are epoxied to the main glass support plate (i.e. also my 8.2 inch diameter window port.)


See photos:
MVC-022L.JPG
Glass plate with ceramic post and copper rod feed-thru, and new glass cylinder shields installed for the fusor cathode assembly


MVC-025L.JPG
Reduce area anode - screen in Fusor vacuum body


MVC-026L.JPG
Cathode installed in the Fusor

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Dennis P Brown
Posts: 1348
Joined: Sun May 20, 2012 2:46 pm
Real name: Dennis P Brown
Location: Glen Arm, MD

Re: Fusor Repair

Post by Dennis P Brown » Fri Dec 08, 2017 10:58 pm

I reassembled my fusor and it easily pumped down to 6 microns using the two stage mechanical pump; it reached the mid 10^-5 torr range using the diffusion pump. So, appears leak tight.

I then back filled with deuterium (14 microns) and struck a plasma, which I ran for a while to burn off contaminates and clean the system. After five minutes of this I was easily able to hold 31 kV and set any current from 26 to 42 ma via setting the pressure using my fine needle valve. I am pleased that my fusor is stable again after the repairs. That issue, at least for now, is addressed.

My next project is to finish the neutron detector 2.5 kV power supply. If that goes well this weekend (besides my other concerns, of course) I may get the opportunity to test a neutron detector. But that is dependent on completing the HV supply and more importantly, getting my counters working well (stable.)

At least I now have my neutron source again.

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Richard Hull
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Re: Fusor Repair

Post by Richard Hull » Sat Dec 09, 2017 7:09 am

Good luck with the detector working out for you.

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
Retired now...Doing only what I want and not what I should...every day is a saturday.

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