Replacing the Coldhead:
- The coldhead can not be removed unless IGRINS is lifted above the leg height. This was achieved with reams of paper.
- The cryostat lid can not be removed when IGRINS is lifted on paper reams. first remove the lid, then lift IGRINS to place paper reams underneath.
- When lifting off the cryostat lid be careful not to bind on the pins. It helps a lot to release the wheel locks.
- Removing the cold shield can be difficult because it is covered in tape. It requires about 6 hours of labor.
- The cold shield sides are removed in a intersecting box (pinwheel) pattern.
- To remove the coldhead you must first remove the getter.
- Also, remove the copper plates as shown in photos. (No photos–20241206)
- The coldhead drops out when specific fasteners are removed. Review photos to see which ones. Do not disassemble entire flange. support from the bottom.
- Disassemble the coldhead flange, based on the photos, and replace all the o rings. Clean and degrease orings.
- Lift the bellows from the bottom to avoid over stressing.
- Lift the coldhead back into IGRINS and fasten into place.
- Reconnect the copper strapping and charcoal box.
- Done.
Items to be completed in the future (was this ever completed?--20241206):
- Bake getters annually
- Slit mask needs more baffles