On August 20, Samuel M. and I again successfully cooled the dewar and ran the pumped pot. We had no problems with plugs in the capillary. There was a vacuum leak into the case. Luckily our pump was able to keep up with the leak and we were able to run several tests.
We put an overload of power on the pumped pot until the pot ran dry. We then reduced the power on the pot gradually and watched the pot refill. This test indicated that the pumped pot had a heat capacity of approximately 20mW beyond the parasitic heat loads (see second figure below).
We first applied a constant power to the capillary. We then ran the pot dry using the heater on the pot and gradually reduced the power on the pot in order to watch the pot refill. The pot had the same cooling power as measured above.
Plots coming soon.