METHOD AND APPARATUS FOR PRODUCING SUPER-LOW TEMPERATURES

摘要

A method and apparatus for producing stable super-low temperatures in a test object for laboratory purposes is described. Three different elongated superconductive elements are bonded end-to-end to form a composite rod. One end of the resulting superconductive rod is placed in good thermal contact with a reservoir containing liquid helium, while the other end of the rod is placed in good thermal contact with the object to be cooled. Each element of the rod is separately subjected under adiabatic conditions to a discrete magnetic field within a separate compartment of a surrounding superconductive shield to trigger a change of the associated element from its superconductive to its normal state with a corresponding drop in temperature. Because of the diamagnetism of the shield, the applied magnetic fields are mutually isolated, and the changes in state of each element are independent of those of the other elements. Such changes in state are discretely triggered in an appropriate sequence to transfer accumulated heat from the test object to the reservoir.