On July 20 Samuel M. and I successfully cooled down the dewar. Again we had no problems with plugs in the capillary. Our cooldown procedure involved keeping back pressure on the capillary. We only pumped on the LHe reservoir after we'd blown out the LN2. We ran several tests to characterize the behavior of the pumped pot.
We added progressively more power to the heater on the pumped pot until the pot ran dry.
Plots coming soon.
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 60mW beyond the parasitic heat loads (see second figure below).
We added progressivley more power to the heater on the capillary heater until the pot ran dry.
Plots coming soon.
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. (Real temperature values are coming soon. A lower resistance corresponds to a higher temperature.)
