Construction techniques for adiabatic demagnetization refrigerators using ferric ammonium alum

摘要

We describe techniques used to fabricate the coldstage of an adiabatic demagnetization refrigerator that uses theparamagnetic salt ferric ammonium alum. We discuss the designof a leak-tight housing for the salt as well as a technique forgrowing ferric ammonium alum crystals that results in a housingfilled with >98% refrigerant. These techniques have proven to bereliable in creating robust single-stage refrigerators. Similartechniques can be used for the second stage of a dual-stageadiabatic demagnetization refrigerator.