Speaker
Gerard VERMEULEN
(Institut Neel (CNRS))
Description
The open cycle dilution refrigerator of the Planck mission had a cooling power of 0.2 $\mu$W at 100 mK during its life of 2.5 years, but future space missions (e.g. Athena+) require 1 $\mu$W of cooling power at 50 mK for a lifetime of at least 5 years.
Helium isotopes had to be stored on the Planck satellite, since the open cycle dilution refrigerator rejects the helium mixture into space after dilution.
This mode of operation is impossible for the future missions with higher cooling power requirements, since the amount of helium needed is too large to embark on a satellite.
Therefore, we have been developing a closed cycle dilution refrigerator by extending the open cycle dilution refrigerator with a helium isotope separator -- also called still -- at low temperature to reuse the $^3$He and $^4$He in the dilution refrigerator.
Liquid and vapor phases coexist in the still and the liquid has to remain in the still under zero gravity conditions.We have performed an extensive test program to confine the liquid helium mixture in the still by capillary forces under "negative gravity" conditions.
Now, we are integrating an "upside-down" still in our dilution refrigerator to test its operation in "negative gravity". We will present the design of the refrigerator and the results of our tests.
Authors
Dr
Angela Volpe
(Institut Néel (CNRS))
Gerard VERMEULEN
(Institut Neel (CNRS))
