He has a project where we need to deposit TiO on sapphire so I am getting this thing ready for coating. I really have not done anything to it since I made all the holes in the base plate in this thread:
http://www.coultersmithing.com/forums/v ... ?f=12&t=44
Wow, been a year and a half!
Got everything put together. The crystal holder for the monitor, a diffuser for gas inlet, power feedthroughs, built a new rack to hold the RF power supply and other stuff. Fired it up and managed to get down to low e-5. I fired up the rag and the problem I was having before reared its ugly head again but this time it wouldn't fall for the same tricks to get it going as before. Last year I found the electronic half of the same model of RGA except in a 200AMU version with electron multiplier. I think I paid $50 for it on ebay. The electronics in the unit are basically little racks, one for input power and communications, one for I/O, and the other holds the cpu board and the main power supply. The cpu rack had the same model not he power supply board but the cpu board itself was a newer revision with a different model number. Figured I didn't have much to loose so I plugged it in and gave it a try. It worked!
Luckily whoever designed it made it so that it gets the parameter info from the rest of the unit so it shows up as it should, a 100AMU rga plus another option which I had not heard of. I got it tuned and it works. First thing I found was a pretty big air leak:
IMG_1220 by macona, on Flickr
You can see the big peaks of nitrogen at 28 and 14 as well as 16 and 32 of O and O2. I brought my little tank of ballon helium over, put the RGA in leak test mode and found a leaky conflat. I think I may have tried reusing a half squished conflat here. Oh well.
After that I managed to get the system down to the mid e-6 range. Not bad for a system sitting at air for a year and a half (The DP section was still under vacuum). After:
Untitled by macona, on Flickr
As you can see, it is full of water. So I took one of those Ushio Ultra High Pressure Mercury lamps and installed it hanging across the two big power feedthoughs and ran the thing off my tig welder, 40v at 6 amps. It seems like it may be an option for outgassing. If you look at the screen on the computer below you can see a yellow line. This is mass 18, H2O in a trend graph, I think 10 minutes for the width. You can see where I first turned on the lamp there is a huge spike in water vapor. At the peak is where I lowered the power on the lamp too much and it went out. It took a while to cool down enough to restrike and you can see the graph where it does and again where I shut it off. Seems to work.
Untitled by macona, on Flickr
Only bad thing is it is rather bright:
Untitled by macona, on Flickr
Untitled by macona, on Flickr
Now I need to make the electrodes to hold the boats, figure out how to hold and heat the substrate and rig up a leak valve to let O2 in to the system. When evaporating Ti02 it decomposes and needs oxygen in the system to go back to it's transparent form.
