Fusion Message Board

In this space, visitors are invited to post any comments, questions, or skeptical observations about Philo T. Farnsworth's contributions to the field of Nuclear Fusion research.

Subject: Going Spherical
Date: Apr 13, 09:48 am
Poster: Richard Hull

On Apr 13, 09:48 am, Richard Hull wrote:

I have about 3 fusor projects going in parallel now and have had some 6" diameter custom 316 stainless hemispheres spun up by Maryland Metal Spinning.

This is a real toughy, but will obviate the need for an outer grid, (chamber positive/gounded). It will also offer a much cleaner system. I have learned to TIG weld stainless pretty well now.

I am machining my own view port from a 2.75 conflat tapped blank flange, and it will have a 1.25 inch clear aperture for limited viewing. (3/8" thick borosilicate glass) I intend to use a single board B&W video camera for remote observation of the poissor. I am a little concerned about the neutrons and the CCD element. At lower fusion levels, this might not be a hassle.

The central grid will be removable with its insulator assembly to allow for replacement and repair. I lucked onto a nice berylia insulator on stainless, mint in box, at a recent hamfest.

There is a lot of fitting, machining, and close tolerance welding to be done and I am to do it all myself.

There is an art in planning the machining to allow for proper welding operations and still meet with the stringent vacuum requirements. I am slowly learning this technique. The learning and experimentation phase is ever ongoing with a one man fusor team.

The 6" bell jar fusor is on a permanent "ready to use" setup for visitors. This was my first neutron producer. It was a very low output system due to low voltage excitation (insulator limited to 15KV) and rough pumping causing a mixed D2/air environment. Multiple pumpings and purgings were necessary to get the D2 ratio up. (wastefull of D2!)

The future 10" bell jar system will go to higher voltage and operate off of a diffusion pump prior to D2 backfilling allowing a 3 order of magnitude increase in D2 level and a corresponding reduction in other gases.

The spherical stainless fusor reactor will go on line later this year if all goes as planned. The snail's pace is dictated by available funds and time, and work stoppages while acquiring the necessary mission critical skills needed to move forward and avoid costly mistakes.

Richard Hull