| 0900 | Continue with cleaning fridge lines, in particular spraying acetone (twice) and then isopropanol from the top of fridge to the second impedance and mixing chamber. Notice that roughly sealed first impedance is also leaking some acetone. Also, clean and polish bottom of mixing chamber and clean still line copper pipe to remove welding residue, oil and other contaminants. |
| 1100 | Continue cleaning methods. Also continue cleaning copper still pipe and additional bellows to be used. It is noted that many bellows and o-rings that had been previously used in the system smell of oil. |
| 1300 | Clean upper portion of mixing chamber. |
| 1500 | Seal up mixing chamber with 100mm indium. |
| 1700 | Put impedance wire back in first (upper) impedance and reseal first impedance. It is now possible to test for throughput as the fridge lines have been sealed. However, when throughput tests are attempted, no flow from still line to condenser line is seen. This could be due to extra acetone collecting in trap just before 4K flange, or oil still in the system, or an issue with the top impedance wire. The acetone issue would be the easiest to fix, so begin with this assumption. |
| 1800 | Set up pumping system such that scroll pump, turbo pump and leak check can all be used on either still line side or condenser line side. Disconnect still line from pump intake/exhaust lines and connect to top of turbo pump structure. Disconnect copper condenser pipe from He cold trap and connect directly to condenser line port. Disconnect other end of copper condenser pipe from back of IGH and pass through wall to pump room. use a clean 16K bellows to connect copper pipe to scroll pump apparatus. Connect external pressure sensor to copper condenser pipe/scroll pump apparatus, and connect He gas line to turbo pump structure. |
| 1900 | Due to setting up pumping system, all portions of system are at atmosphere. Pump out lines of pump system. Notice that these lines have begun freezing, as they still contain acetone. Use heat gun to remove acetone and pump down the lines. Once external pressure sensor reads below 0.1 mbar, open valve to condenser side of fridge. Commence pumping on condenser line side of fridge with scroll pump, with gate valve open. After several minutes (and more acetone heating in the fridge lines) it is noted that external pressure sensor has stabilized at 1.2E-1 mbar. Closing the gate valve (and thus isolating the large copper still pipe), lowers the external pressure sensor below E-2 mbar. This is an indication of throughput. Commence pumping on still line side to reduce this pressure. Once pressure is below E-2 mbar and all noticeable acetone has been heated out of the system, switch to pumping on condenser side once again, with gate valve open; external pressure sensor stabilizes at roughly E-2 mbar and slowly dropping. Commence pumping on both sides of fridge, and switch to turbopump. Leave overnight. |