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Thread: Flowing gas CO2 laser conversion from sealed gas

  1. #21
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    Yeah, it is expensive. Even used they stuff is not cheap. Nothing to do with vacuum systems is.

    Yes, you can get a pretty good idea of the mixture in the tube.

    You are thinking of a normal optical spectrometer where it will read emission or absorption and compare that to known samples. This works differently. It ionizes gas and the ions are sorted by their mass weight. For example water has a mass of 18 amu (atomic mass units), two hydrogen at 1 amu, and one oxygen at 16amu. So you get a peak at 18 amu on the graph. But it is possible for other things to have a mass of 18 as well. What makes things easier is that when the gasses are ionized in the chamber and accelerated some of the molecules are broken apart and maintain a statistical ratio. So water breaks up into a few other peaks, One at mass 1 for Hydrogen, and also another peak at mass 17 for HO. You may also get a peak at 16 for monoatomic oxygen. In the graph below you can see an analog plot off my 100 AMU Dycor RGA. It interfaces to a PC so I just use an old laptop to control it. You can see the peak at mass 18 an the little peaks below it. At the time I had a pretty large air leak in the system so you see two massive peaks at Mass 28 (Nitrogen, N2) and Oxygen O2 at Mass 32. You also see a peak at 14 from monoatomic nitrogen and a slight bump from carbon at AMU 12. The bump at 40 is Argon. Xenon is a pretty massive atom at 132 AMU and has isotopes up to 138. So I can measure it on my portable unit but not my big system.


    IMG_1220 by macona, on Flickr

  2. #22
    mixedgas's Avatar
    mixedgas is offline Creaky Old Award Winning Bastard Technologist
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    Typical elements added to Co2 for regen Xenon, carbon monoxide, Deuterium, Water vapor and . (Yes, water vapor) heavy hydrocarbons.
    Dont know if the Asians are using them. Nickle and gold films are the catalysts.

    The way to align a glued tube involves a frequency swept laser. You then treat the cavity to be aligned as a giant and cruddy Fabry Perot cavity, and check the transmission vs sweep for a peak or null, depending on the setup. There are patents on this technique. Which means they know about it.
    You need to make more then one tube to do it, as you need to graph the detector data vs output to find the winners.

    Not easy with a co2, the required fast, sensitive detector is not cheap.

    I've yet to see a picture of catalyst rings in a Asian tube, so might not be the classic catalytic regen mix. That would explain the short tube life.

    Steve

  3. #23
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    Quote Originally Posted by GregR View Post
    About six months ago I purchased this gas mixing box. It is sitting at a friend's place and shipping is too expensive. Perhaps you can suggest parts to yank off it then connect up to a new setup.

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    If you still have it I would love to buy it from you

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