How is everybody mounting their capilliary tubes?

For the design and construction details of ion guns, necessary for more advanced designs and lower vacuums.
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Real name: Ian Krase

How is everybody mounting their capilliary tubes?

Post by ian_krase » Fri Sep 15, 2017 7:54 am

The capillary tube I use for letting gas into my system is a .007 inch ID hypodermic needle, which is pretty thin walled and therefore does not match any kind of tube size or anything like that. I'm curious how people are making vacuum and gas tight seals between capillaries like this. Most people describe using Hysol or similar to glue them into tight-fitting holes --is there a better way?

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Dennis P Brown
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Re: How is everybody mounting their capilliary tubes?

Post by Dennis P Brown » Fri Sep 15, 2017 10:48 am

I have done this many times and it works for high vacuum - I first get a small diameter 'capillary' copper tube (can be obtained at some hardware stores or online), that fits the smallest compression fitting (believe 1/16 inch diameter are available.) I then use conductive epoxy when I need electrical contact or just plain vacuum grade epoxy to seal the needle in the small diameter copper capillary tube (I shim by wrapping the needle with foil so it makes a tight fit inside the copper capillary tube.) I then use the small compression fitting to seal/hold the copper capillary tube in a compression fitting assembly. This assembly easily is fitted (using std stuff) to any swagelok system of larger size diameter or a flange with a threaded hole.

John Futter
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Re: How is everybody mounting their capilliary tubes?

Post by John Futter » Sun Sep 24, 2017 10:13 pm

I have always soft soldered these.
see my previous posts on the correct liquid flux
good to ten to the minus ten millibar

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