β Scribed by R.L. Fagaly; D.N. Paulson
No coin nor oath required. For personal study only.
We examine the performance of a dilution refrigerator from an enthalpy standpoint. Taking into account imperfect heat exchange due to Kapitza resistance and temperature dependent effects allows calculation of the effective surface area in the heat exchangers. Knowledge of the effective surface area allows prediction of ideal refrigerator performance as a function of operating temperature, circulation rate and applied powerβ’ This permits diagnostic evaluation during refrigeration operation. The minimum achievable temperature is shown to be dependent on viscous heating effects. Performance analysis was used to redesign part of a high performance dilution refrigerator, reducing the minimum temperature from 3.2 mK to 2.9 inK.
π SIMILAR VOLUMES
A very compact dilution refrigerator has been developed. Although the ultimate temperature reached is as low as 160 mK in continuous mode and 92 mK in one-shot mode, it is so easy to run the refrigerator that one can finish an experiment within a day.
The history of dilution refrigeration is traced back to 1951 when H. London suggested the possibility of cooling by mixing He 3 and He 4. The first dilution and cascade refrigerators are described, followed by continuous refrigerators and L yden dilution referation. Finally the Kamerling Onnes Labor