next up previous contents
Next: Warming Up Up: Low Temperature Operation Previous: Closed Loop Temperature Control   Contents

Reaching Base

The base temperature of this system is $ \sim 7$ mK, depending on the cold mass.

To reach base temperature turn off the heat load on the Mixing Chamber, and keep the heat load on the still around 4mW. The heat load on the still is required to keep the cooling power high. The optimal heat load on the still to reach base temperature will depend on the cold mass. For an unloaded MC, it was found to be $ \sim 4$ mW, but you may need to tweak this value to find the true base.

The RuO$ _2$ thermometers will lose accuracy around 50 mK and will bottom out completely at $ \sim 20$ mK. Below this, you will need an alternate measure of the temperature.

Jonathan Ouellet 2014-08-26