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: various instrumentation and parts questions
Date: Jul 06, 00:58 am
Poster: Richard HullOn Jul 06, 00:58 am, Richard Hull wrote:
How much voltage can those things take? Are things like truck plugs etc rated for higher voltages? I take it you just weld them into a flange and away you go, or is there something more? I also want to figure out how to make coax feedthroughs for instrumentation.
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I have placed over 25kv on my arrangement. Make sure to get good silicone boots for the plug bodies as well. These help supress corona.
Coaxial feed throughs are tough. I have several ceramic beam power tubes from hamfests which I paid a buck or two for. I break the things up for the ceramic 8 pin vacuum sealed base. This yields a nice metal to ceramic seal. The metal can be soldered epoxied or brazed to a flange or chamber. You now have a good 8 pin high current low voltage fitting. RH
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>>Regular Shellac works OK, but there are some superb "glops" that outgas no worse than 10-6 torr which are specially formulated to dry and yet remain flexible or rubbery.
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> Names? I have access to an electric kiln, so I can temperature cure if necessary.
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I gave one.. Inland Seal another Dux seal. RH
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>>There are special RTV's, Epoxys and sealants.
>>I have used "Inland Seal" a lot (from Inland vacuum), but you need to let it cure for about 4 days.
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> Does it heat cure?
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Yes, but slowly and at only slightly elevated temps as it is a volatile distillate based thing. RH
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>>Maryland Metal Spining
>>contact Chuck Mitchell
>>1 (410) 466-6400
> How did you rig the flanges? I've priced real flanges from Leskers etc and the prices are absolutely prohibitive. I was thinking of buying SS or aluminum flanges for some other application and having a gasket groove put in on a lathe. I have access to a TIG rig and someone who knows how to run it, so the welding won't be a problem.
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I found large SS pressure flanges at a local junk yard for $20.00 each and spent 40 hours at a milling machine making them into siutable flanges with indium seals.
For the next 6" fusor IV I have just purchased two formal Duniway conflat 8" rings (6" openings). Never agin will I slave away at the mill. RH
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> Thank you for taking the time and energy to answer my questions; you have been extremely helpful.
Thats what we are all here for. No problem.
Richard Hull
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> Pierce Nichols