Homemade Feedthrough

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Andrew Robinson
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Re: Homemade Feedthrough

Post by Andrew Robinson » Mon Jul 07, 2014 5:09 pm

To bring things back to the friendly side :) Dan have you done any load testing on your DIY feed through? What is the maximum potential you are expecting to push through that thing? I'd be curious to see where it fails, especially considering the minimum surface path length. I'm curious to see what the flash over voltage is. What's the creepage distance? Looks to be about 6-8 inches or so? Looks nice. Well done.
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Liam David
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Re: Homemade Feedthrough

Post by Liam David » Wed Oct 01, 2014 12:17 am

Scratch the link to the compression fitting-They must have been bought out.
I'm re-posting because I cannot edit my previous post.
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Re: Homemade Feedthrough

Post by Jack Rosky » Sun Oct 05, 2014 11:21 pm

Looks very well done Liam!
Do you happen to have a schematic drawn up or more pictures of the assembly process. I am very curious as to how you set this up and how it looks on the grid-end of the feedthrough.
Thanks,
Jack Rosky
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Re: Homemade Feedthrough

Post by derekm » Mon Oct 13, 2014 5:07 pm

What is the diameter of the conductor inside the feedthrough?
This is important as the electric field is related to the diameter or the conductor.

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Re: Homemade Feedthrough

Post by Bob Reite » Mon Oct 13, 2014 10:54 pm

I'm curious as to what voltage it has been tested to. Guess I'll need to look up the dielectric strength of alumina and figure out the theoretical maximum this build can take voltage wise.
The more reactive the materials, the more spectacular the failures.
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Re: Homemade Feedthrough

Post by Jake Wells » Tue Oct 14, 2014 11:44 am

This is the part # 8746K16.
http://www.mcmaster.com/#alumina/=u5afbt
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Re: Homemade Feedthrough

Post by Andrew Robinson » Tue Oct 14, 2014 9:45 pm

Why not post the direct link to the specs: http://www.mcmaster.com/#8746k16/=u5i5f7

It should be noted though that McMaster has been known to be "off" in their specs before. You would be better off looking to the manufacture for accurate specs on materials. McMaster is a good general starting place though.
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Re: Homemade Feedthrough

Post by Jack Foulkes » Sun Dec 07, 2014 4:28 pm

Hi, I am a university student looking to construct a cheap HV feed-through and inner grid. If you don't mind, I have a few questions:

- have you successfully built your fusor with this feed-through system?
- How does the wire actually connect to the inner grid, and why do you need an insulated wire that connects the feed-through to the inner grid, instead of just connecting the contents of the alumina tube to the grid directly?
- How exactly does this part fit onto the chamber?

I am very new to the fusor forum and so some of may questions are probably quite stupid, so just tell me if they are (but I would(obviously) prefer constructive criticism). Thanks alot for any information or advice you can spare.
viewtopic.php?f=6&t=9856

Jack Foukles

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Re: Homemade Feedthrough

Post by Andrew Robinson » Mon Dec 08, 2014 8:36 pm

Jack you might want to spend some time in the FAQs. Unless I am misunderstanding one of your questions:
Jack Foulkes wrote:How does the wire actually connect to the inner grid, and why do you need an insulated wire that connects the feed-through to the inner grid, instead of just connecting the contents of the alumina tube to the grid directly?
it seems you have a basic conceptual misunderstanding of what this component is actually for. Please do some more reading first.

If that's not the case and I'm mistaken, can you either rephrase your question, or can someone else please chime in?

To answer your other question, go search any vacuum component manufacture for Conflat compression fittings. For example: http://www.pchemlabs.com/subcatagoryb.a ... ssion-Port

Also, in Liam's very first post, he references the original designs creator. If you check that link you will find many more examples and descriptions that will answer many of your questions.

As a university student, you should be well accustomed to doing your research beforehand. My old professors would kick me out of their offices if I didn't do my research first.
I can wire anything directly into anything! I'm the professor!

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Liam David
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Re: Homemade Feedthrough

Post by Liam David » Fri Dec 19, 2014 12:15 pm

It's been a long time since I posted. School has left me with almost no spare time.

The feedthrough has only been tested to 15 or so kV with a NST. I'm working on a new HF x-ray transformer, so that will be the final test for the feedthrough.
The internal conductor is just a (0.1" diameter?) aluminum wire shoved into the alumina tube to make contact with the Swage-lok compression cap. The inner consists of a single piece of tungsten wire with two long "legs" to make sure it doesn't fall out.
Here are some CAD pictures.
Image
Image

And the whole chamber with a work-in-progress diffusion pump.
Image

-Liam David

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