> 1) What could I use as a vacuum gauge? I need to have a resolution of about > .1mbar, and a range of 1bar down to 1mbar or so. Does anyone know where to > buy those at a reasonable price?
There are two main choices here. You can look for a "thermocouple gauge", which is fairly simple, inexpensive, and robust. It isn't poisoned by exposure to atmosphere, which is also nice. You can also make your own manometer out of glass tubing, but it will be tricky to read at the low end. > 2) The vacuum pump I am considering to purchase is a pump that is used in > refrigeration technique. Is it essential to use a 2-stage pump? I have no > experiences in this area, that is why I ask. I just assume that with washing > the tube I can make up for some of it. For gas tubes, you can get away with less than for vacuum tubes, but a good vacuum always helps with tube life. You can make or buy a diffusion pump to get a lower vacuum, or use two mechanical pumps in series. With the frequent pumpdowns, it'll take extra effort to keep your pump oil clean. A turbomolecular pump would be dandy, but they're large, loud, and expensive. An ion pump probably wouldn't help, as they're designed for higher vacuua than you're working with. It's worth a try with a single-stage pump, cleaning your elements well, and degassing thoroughly (heat the glass and elements while pumping to drive off adsorbed gases). You could also use a getter for additional cleanup, but that adds to the complexity of your tubes. - John -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To post to this group, send an email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
