27 December, 2000

More coldhead maintenance

Today, we started the process to cool FLaMR again, and to cool Wanda which now also has a new coldhead. Before the dewars can be cooled, we need to make sure that there are no contaminants in them that might freeze and cause problems at low temperatures. For FLaMR, this meant flushing the system with helium gas- putting pressurized helium into the dewar, and releasing it many times. This dilutes any other gasses that might be in the dewar, leaving mostly helium. For Wanda, since we had just put on a new coldhead, we wanted to flush the system of all gasses, by making the inside a vacuum. In the morning we put the new coldhead in place, and in the afternoon tried to get a vacuum inside of the dewar. Getting a vacuum inside would also indicate if there were any gas leaks that would cause problems for keeping the system cool. The vacuum pump was not working as well as we had expected, so once again we took off the coldhead, replaced one of the seals, and put the coldhead back on. We started the vacuum pump again, and it seemed to be doing its job much better, so we went to dinner to let the pump evacuate any gas overnight.

Wednesday night is movie night at the South Pole. This weeks feature was “Poles Apart”, a documentary about Ann Bancroft’s all women team skiing across Antarctica in 1993-1994. This was of parcticular interest, because Ann Bancroft is again traversing the continent on skis, this time with a Norwegian, Liv Arnesen. They were expecting to be at the South Pole this week, but are behind schedule and will arrive in January.

Here Chris Martin attached the vacuum pump (foreground) to Wanda.