elizabeth Posted February 13, 2005 Report Share Posted February 13, 2005 Hello everyone,quick question. I have made a pyrex chamber with two elecrodes on the ends, when a charge was applied it looks like the tungsten oxidized after 4 tests of 5 minutes each? It looks black and the helium turned to a red plasma. What do you think about Kovar. I got two elecrodes graded to pyrex and I think I will have them put into the ends insrtead of the tungeston which also had a littel urnamiun glass. It is for a science project for school.Elizabeth Quote Link to comment Share on other sites More sharing options...
TeleMad Posted February 14, 2005 Report Share Posted February 14, 2005 Are you trying to construct a light bulb from scratch? In a typical tungsten filament light bulb, the glass bulb is under vacuum to make the tungsten filament last longer. Quote Link to comment Share on other sites More sharing options...
GAHD Posted February 14, 2005 Report Share Posted February 14, 2005 Yes, you can also fill the tube with various noble gasses to different effects. But please, explain the experiment furthur, with whatever visual aids you can. It sounds interesting. Quote Link to comment Share on other sites More sharing options...
elizabeth Posted February 14, 2005 Author Report Share Posted February 14, 2005 Hi again,I had a pyrex tube made with electrodes on each end. On the side of the tube in the center there is a germanium viewing window and on the other side is a steel plate both are 2" in diameter. with each gas I tested it was taken down to 0Torr and then back up to 7 Torr with the gas put in. I tried argon Neon and Helium. I viewed with an infrared imager to see if plasma obstructed viewing. Not much difference. Got any ideas of another type of gas to use? I am hoping that changoing the electrodes will help. The plasma on the last test, the Helium started to spiral around the tube. pretty cool. but it was red note yelloow like I thought it was supposed to be. Oxidation of the electrodes or maybe the RTV that I gluesd the germanium and steel on with???Elizabeth Quote Link to comment Share on other sites More sharing options...
GAHD Posted February 14, 2005 Report Share Posted February 14, 2005 well I know a He-Ne mixture is used in red lazer tubes, so I'd assume helium glows read. Try Xenon? Quote Link to comment Share on other sites More sharing options...
C1ay Posted February 17, 2005 Report Share Posted February 17, 2005 Hello everyone,quick question. I have made a pyrex chamber with two elecrodes on the ends, when a charge was applied it looks like the tungsten oxidized after 4 tests of 5 minutes each? It looks black and the helium turned to a red plasma. What do you think about Kovar. I got two elecrodes graded to pyrex and I think I will have them put into the ends insrtead of the tungeston which also had a littel urnamiun glass. It is for a science project for school.Elizabeth It sounds like you are having a problem with the evacuation in removing all of the oxygen. Earlier in life I worked on vacuum furnaces which had to be oxygen free in operation. To achieve this we had to not only evacute the chamber, we found it necessary to post flow a quantity of nitrogen thru the chamber to displace any remaing molecules of oxygen. We then evacuated the nitrogen and backfilled with helium to check for leaks with a spectrometer. Your problem with oxidation should subside when your procedure is effective at removing all of the oxygen. Perhaps my past experience will help. Good luck. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.