Abstract: A step-type heat-exchanger particularly useful for low temperature applications comprises a housing including a thermally-conductive member partitioning its interior into first and second chambers, and a sintered spongy layer of fine thermally-conductive particles bonded to each of the two opposite faces of the thermally-conductive member so as to be exposed for direct contact with a heat-exchange fluid when introduced into each of the two chambers. Also described are a method and apparatus for making the heat-exchanger, in which method and apparatus aluminum pressure plates are applied under heat and pressure to sinter the thermally-conductive particles to form the sintered spongy layers bonded to the opposite faces of the thermally-conductive member.

Abstract: A multiple-chamber cooling device particularly useful in a dilution refrigerator in which a working liquid is passed successively through a plurality of chambers in each of which a fraction of the working liquid is allowed to evaporate to cool the remaining working liquid. The cooling device comprises a common body member of low thermal conductivity formed with a plurality of spaced bores each defining one of the chambers, the outlet end of each chamber bore being connected by a passageway to the inlet end of the adjacent bore for passing the working liquid from one to the next chamber bore as a fraction of the working liquid is evaporated to cool the remainder.