| Dirty LN2 Coldtrap | The pressure in G2 begins to rise while the mixture is circulating. | Switching Cold Traps Mid-Circulation and Clean LN2 Cold Trap |
| Oil in Fridge | High base temperature, oil smell in bellows, throughput at 77 K but not 4.2 K | Inner Fridge Maintenance |
| Not enough mixture in fridge | High base temperature, oscillations in temperature | If more mixture remains in the dump, open V14 for short time intervals (such that G2 does not rise above 800 mbar) to bleed mixture into system. Once a sufficient amount is back in the fridge lines (likely all of mixture), give 1-3 hours for system to cool down to a new base temperature. |
| Leaky Indium Seal | Failed IVC leak check. Rise in base temperature. Rise in IVC pressure. | Leak rates as high as 545E-9 mbarL/s are acceptable for shorter runs (see 2015/04/16). Some differential leaks that occur when the main bath is filled with gas from vacuum but then vanish are also acceptable to run with (see 2015/04/15). If the leak rate is too high to proceed, you can lower the main bath (if raised) and conduct a spray test. If any spots show a noticeable leak, tighten these screws before raising the dewar and continuing. This however, is only likely to help smaller leaks. Larger leaks will require you to reseal the IVC flange. |
| Leaky wizard staff | Failed IVC leak check, failed spray test | It is possible that tightening the double flange will fix the leak. Otherwise opening and resealing the wizard staff flanges might possibly fix the problem (Note: this requires you to warm up and fill IVC with N2 gas before opening). In extreme cases, the wizard staff might have been scratched. Removing the wizard staff and commissioning the workshop to polish it might be necessary. Replacing the O-rings might also reduce the leak, but that requires removing the wizard staff. Conduct a spray test to verify that it has been fixed before continuing. See 2015/04/09 for more information. |