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Registered Member #1389
Joined: Thu Mar 13 2008, 12:50AM
Location: Pittsburgh, PA
Posts: 346
If you are having trouble with the pump, you can use old CRT monitors as vacuum reservoirs and use a punch to put a tiny hole in it, then seal a hose over it to suck out the air in your tube.
Also with a CW, Mates has a nice thread on his homemade one here. He was hoping to get up to 300kV, but I don't know if he ever did.
Registered Member #93
Joined: Thu Feb 09 2006, 04:11PM
Location: Houston, Texas
Posts: 64
A little off-topic, but if the availability of a vacuum pump is a problem, a sorption pump might work for you. It looks "relatively" simple to implement ( http://www.sas.org/E-Bulletin/2001-12-07/features2/features.html ) and it can evacuate a 1 liter volume down to 10 millitorr in about 20 minutes. In addition, there's not a lot to wear out (other than having to replenish liquid nitrogen).
Registered Member #1548
Joined: Mon Jun 16 2008, 09:22PM
Location: Ohio
Posts: 61
The CRT method for the vacuum is an okay idea, except for the fact that my laser gas is constantly flowing. So, I would need a mechanical pump. Right now I am using a compressor salvaged from a window air conditioner. I went to all of my local shops asking for fridge compressors, and none of them had any spares . Also, RickR, that might work, except the source of liquid nitrogen. It would probably be more economical in the long run just to buy a good vacuum pump. I am going to start building a two stage CW soon, so I will take a look at that thread.
Registered Member #1321
Joined: Sat Feb 16 2008, 03:22AM
Location:
Posts: 843
You can get a mechanical pump (two stage rotary vane type) rather cheaply on ebay. Since what you're doing doesn't require a high volume throughput, you can use a small pump, which you can get for 100 - 120 dollars or so, and even cheaper if you get a used or "refurbished" pump.
BTW, with regard to a sorption pump, as someone suggested, notwithstanding the problem of somehow achieving continuous pumping (if yours will be a slow-flow laser), a sorption pump based on molecular sieve adsorbent probably won't work well in your application as it will trap CO2 more effectively than N2 and He (it may not trap He at all) thus it will significantly change the composition of your gas mixture as it pumps.
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Building a CO2 Laser power supply
. Also, RickR, that might work, except the source of liquid nitrogen. It would probably be more economical in the long run just to buy a good vacuum pump. I am going to start building a two stage CW soon, so I will take a look at that thread.