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Beginning an automated Pre-Cool

At this point, the automation takes over.

At this point you will hear lots of clicks and whirring. This is expected. From this point on, it takes roughly 16 hours to cool down to 3K, though it can be longer, depending on the mass mounted in the fridge.

Pre-cool is complete when PT2 reaches $ \sim 3$ K. The still heater and mixing chamber heater will be turned all the way up to prevent condensing in the pre-cool lines. This will result in the temperature of the still, 100mK plate and mixing chamber being roughly 10K. If you plan to head down to base ( $ T_{\rm MC}<100$mK ), you are ready to [sec:cooldown.pre.empty]empty the pre-cool circuit.

By turning down the heater power you can drop the temperature of the MC plate to $ \sim 4$ K. Though, this may cause the helium to condense in the pre-cool lines, and require boiling off the liquid to empty the pre-cool circuit.


next up previous contents
Next: Empty the Pre-Cool Circuit Up: Pre-Cool Previous: Thermometry   Contents
Jonathan Ouellet 2014-08-26