Venting the BOS

• Start with system: Cryo gate valve open, all-metal valve closed, 1/4-turn valve closed, viton seal valve closed, scroll pump off, BOS ultra-high vacuum, roughing manifold low vac (dirty)/atm.

Pump-Purge the Roughing Manifold

1. Turn on N2 to roughing manifold

2. Turn on scroll pump

3. Open viton seal valve between scroll pump and roughing manifold

4. Pump out roughing manifold, it should get to low mT (4-20mT)

5. Turn off scroll pump

6. Open 1/4-turn valve to N2 purge roughing manifold

7. Look at relative pressure gauge and get it to read zero (not over!), then close 1/4-turn valve

   • (We have now pump-purged once)

8. Turn on scroll pump to pump out roughing manifold

9. Turn off scroll pump

10. Open 1/4-turn valve to purge roughing manifold

11. Look at relative pressure gauge and get it to read zero (not over!), then close 1/4-turn valve

    • (We have now pump-purged twice)

12. Turn on scroll pump to pump out roughing manifold

13. Turn off scroll pump

14. Open 1/4-turn valve to purge roughing manifold

15. Look at relative pressure gauge and get it to read zero (not over!), then close 1/4-turn valve

    • (We have now pump-purged thrice)

16. Turn on scroll pump to pump out roughing manifold

17. Close viton seal

18. Turn off scroll pump

Prep Filaments and Valves for Vent

1. Turn off RGA

2. Close gate valve, see pressure creep up

3. Turn off ion gauge

4. Make sure any other filaments or parts are off or in proper state

• Current system status: cryo GV closed, all-metal valve closed, 1/4-turn valve closed, viton seal valve closed, scroll pump off, BOS high vacuum, roughing manifold low vacuum (clean).

Vent

1. Slowly open all-metal valve

2. Once all-metal valve is a little open, open fully (not too far though)

3. Slowly open 1/4-turn valve a little to bring up BOS pressure

4. When relative pressure gauge gets to 0, close 1/4-turn valve

   1. At 0 or very slightly over is good. Do not pressurize the BOS or have it under 0

• Current system status: cryo GV closed, all-metal valve open, 1/4-turn valve closed, viton seal valve closed, scroll pump off, BOS atm, roughing manifold atm.

BOS Use

• We are now ready to start inserting/removing an effusion cell or whatnot.

• Whenever the BOS is opened to the glovebag (blank or cell removed), the 1/4-turn valve should be opened so that there is a flow of N2 out of the BOS.

• The pressure of N2 going into the BOS (and then out of the BOS arms) must be higher than the glovebag pressure.

• When no ports are opened, the 1/4-turn valve must be closed to prevent over-pressurizing the BOS.

Pumping Down the BOS

Once the BOS opening task is completed, the chamber is pumped back down to UHV.

Pump down to Rough Vac

1. Ensure that the green quarter-turn valve is sealed to prevent UHP N2 from flowing to the chamber.

2. Start the scroll pump on the roughing manifold while opening the Viton seal valve.

3. Monitor the PG pressure until it gets below 1 Torr.

4. Close and seal the all-metal valve between the BOS roughing manifold and the chamber.

Crossover to UHV

1. Plug in the power to the cryopump gate valve to open it.

2. Monitor the temperature monitor of the cryopump. It should rise a bit then recover.

3. Once the cryopump is open to the chamber, the ion gauge can be turned on. Pressure should be in the high-7s.

Wrapping Up

1. Close the Viton seal valve between the scroll pump and the roughing manifold.

2. Turn off the scroll pump.

3. Shut off UHP N2 at the wall regulator.

4. Turn down the glovebag air to 0-10 psi or off