| 1845 | After sealing most mixture into the dump we attempted to cryopump the remaining mixture from G2/pump area. We began with G2~750 mbar. After putting the cryopump stick into the LHe dewar and opening V13A, V13B, V11A, V11B, V7 and vent speedivalve (keeping manual cryopump valve closed), the pressure in G2 dropped to ~300 mbar. After opening the manual cryopump valve the pressure in G2 further fell to ~180 mbar. However, the pressure in G2 then began to rise. We closed 13A, but the pressure in G2 continued to rise to 578 mbar. The pressure in P1 remained at roughly .013 mbar during this, suggesting that this pressure was not coming through V6. We then opened V13A once again, and the pressure in G2 began to drop to 413 mbar before rising again. At G2=427 mbar we turned off the He3 pump and closed V13A and V13B, the pressure continued rising. At G2=562 mbar we closed the manual cryopump valve. The pressure in G2 continued rising and at 590 mbar we turned the He3 pump back on, causing G2 to jump to ~704 mbar and became somewhat stable. With G1=16 mbar (at the start of cryopumping it had been at G1<1 mbar), we opened V13A and V13B, causing G2 to drop. When G1=21 mbar and G2=379 mbar we began to slowly open the manual cryopump valve. When the cryopump valve was fully opened G2=391 mbar and G1 = 24 mbar. We then closed the manual cryopump valve (G1=25 mbar, G2=400 mbar). We then closed all valves on IGH (G1=27 mbar, G2=434 mbar and rising). We then opened V2, V4, V7 (G1=506 mbar, G2=508 mbar and rising). Then we pulled the neck of the cryopump from the dewar and opened the manual valve, causing G1 to rise to 930 mbar (G2=622 mbar). We then closed V4 and the manual dump valve (G1=871 mbar, G2=627 mbar). To retrieve that last bit of mixture between the dump and the cryopump we closed the manual cryopump valve and lowered the cryopump neck back into the dewar. We then opened the cryopump valve until G1=0.5 mbar. We then closed the manual cryopump valve, V2 and V7 (G1=1 mbar, G2=628 mbar). |