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: Re: Vacuum technology and costs
Date: Mar 24, 2:25 pm
Poster: Hal Clark

On Mar 24, 2:25 pm, Hal Clark wrote:

>I suggest you check for used semiconductor processing equipment. Most of it has the very best valves and gauges, but quickly becomes obsolete, and is sold for pennies on the dollar. I would also like to see you using oil-free vacuum pumps, as the oil type will backstream and contaminate your work.
My work with the fusor is on hold for warmer weather as the lab is a bit cold just now. I have taken most of the winter to work up my neutron detector and secure better vacuum fittings.
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>I find that the mechanics of securing a good vacuum which can hold without any leaks, is not easy. Even though 1 micron (10-3mm or torr) is not considered more than a moderate vacuum by true "vacuum heads", it is still a dificult task to bring in all the components and connections into the fusor chamber and have it truly air tight.
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>Vacuum HV insulators, fittings, valves, etc. are very, very expensive. Simple store bought ball valves can work OK, but just aren't up to the task over the long haul.
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>My third fusor will use a mixture of professional "Conflat" and "Quick Flange" High Vacuum fittings. The rotatable Conflats are the ultimate vacuum fitting but run about $50.00 per connection with no plumbing included!!
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>The "QF" flange fittings allow for quick disassembly at lower relative cost. (about $20.00 per connection - no plumbing included).
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> A good stainless bellows vacuum valve in a brass body with solder sockets (lowest priced vacuum valve) is about $120.00.
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>While a basic fusor can be made up with a single valve, a proper system would require a minimum of 2 valves. A lower pumping system (diffusion pump version) might be better served with 3 valves.
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>As I am an electronics engineer, the electrical/electronic bothers are actually a snap. It is the vacuum area that I am struggling with.
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>Now that I have a good handle on all expenses, I would imagine a listing of costs would fall as below:
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>1. Total neophyte, no equipment, no skills in the multiple technologies involved.
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>A. Vacuum system cost for crude demo system. with all equipment brand new...... $800.00
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>As above with used pump.... $300.00
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>B. Vacuum system for a good, working, neutron producing fusor with all new equipment..$2000.00
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>As above with used and lucky finds on the most expensive items................$700.00
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>C. Electronics for demo system version of fusor purchased new but hand made......$300.00
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>As above but with used or scrounged parts...$50.00
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>D. Electronics for complete working, neutron producing fusor with neutron detection system. made up by hand from all new parts and components.
> ..........$2500.00
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>as above, but with all lucky finds, hamfest buys and used components...............$600.00
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>E. Gas delivery system includes 20 liter deuterium cyclinder and lines, regulators and simple leak or bleed valve. new ............$400.00
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>As can be seen a hapless neophyte with no skills and a desire to build a demo fusor might be out as much as $1000 and a working, neutron producing model might cost $4500!
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>If the same person is a good scrounger and knows folks who might help him assemble parts of the system (ham radio operators, etc) a demo system can cost as little as $600.00
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>A neutron producer can cost as little as $1500.00
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>The neophyte will have to immerse himself into the study of a lot of disciplines and this means a lot of books and time spent in libraries.
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>ALL THE ABOVE CHANGES DRAMATICALLY FOR A VETERAN EXPERIMENTER OR AMATEUR SCIENTIST!
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>Costs can plunge to around 50% of the above costs based on what someone already has on hand. I consider myself exceptional, having been an experimenter for 45 years with associated accumulation of STUFF. I had a vacuum pump on hand (doesn't everyone?) All of the electronics components was on hand. I have built one demo fusor and one demo/neutron test bed fusor and am working on a third deep pumped fusor. I figure I am out about $1000.00 with little needed to purchase inorder to continue to make fusors for a while.
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>I know of only 3 other amateurs who have or are working on assembling fusors.
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>Good luck to anyone who attempts a fusor.
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>Richard Hull
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