Quick Description: If you have a gas line that you have connected to your system (typically through a leak valve), you want to bake it and make sure it is clean before connecting with your UHV system. Often, you will be using a gas bottle (Ar, H, etc...) and this should be fairly clean but requires a few rounds of flushing to ensure that a pure material leaks into your chamber.
The Point: Pure gas.
Prerequisites: Set up the pump cart.
Notes:
- Bake the gas line
- Ensure that the two gas valves are open (one connects the gas bottle to ambient/pumping and the other to the chamber).
- Start the pump cart (see link above).
- Begin the bake. On the STM system, there are two bake plugs attached to the Argon line. On the old XPS, there is only one plug attached to the Argon line. The voltage is ~55V and the time span is about 2 hours (or overnight).
- Turn off baking and let cool for 30 min or so.
- Flush cycles
- Close the gas valve to the pumping and open the gas bottle. This fills the line with gas.
- Then close the gas bottle and SLOWLY open the gas valve to the pumping. This flushed the gas line. Watch the pressure to make sure that you're not making the turbo struggle too much. It's generally a good idea to stay under 20 W, but this does vary for different pumps.
- Cycle through this about 5-6 times and you should be good.
Quick Description: For small things that need to be pumped, our lab has a pump cart which includes a rough and turbo pump. Common applications include cleaning out a gas line, freeze/thaw cycles, pumping down a temporary chamber, and more.
The Point: A quick set of pumps to get the job done.
Notes: You may want to check that everything is plugged in and connected. If you are experienced, this should make intuitive sense to you. Otherwise, you can check with a more experienced labmate.
- Open the turbo/chamber valve. Open the turbo/rough valve. This allows everything to stabilize to the same pressure.
- Begin rough pump, wait a little bit so that again pressure can stabilize. It should be able to reach at least 10^-2 torr (and for a new, good pump 10^-4 torr), and ideally you can check this with a pirani gauge.
- Turn on the turbo and wait for it to spin up to full speed and low power. If this does not happen, you may have a leak that needs to be addressed or a problem with your pumps (for example, if your turbo is back by an oil pump, this pump may have spewed a bit of oil).
