NOVEL CRYOCOOLER REGENERATOR DESIGNS

WE PROPOSE TO DESIGN AND EVALUATE THREE NOVEL REGENERATOR CONCEPTS THAT HAVE THE POTENTIAL FOR SIGNIFICANTLY IMPROVINGTHE COEFFICIENT OF PERFORMANCE OF STIRLING-CYCLE CRYOCOOLERSAT TEMPERATURES BELOW 20 K. THE INNOVATIONS CONSIST OF TWO TYPES OF ACTIVE REGENERATORS AND A NOVEL COMBINATION OF MATERIALS THAT YIELDS A HIGH SPECIFIC HEAT EVEN AT LOW TEMPERATURES. THE ACTIVE REGENERATORS ACT AS IF THEY HAVE AN INFINITE SPECIFIC HEAT. PREVIOUS WORK INVOLVED MORE CONVENTIONAL MATERIALS AND INTERACTION WITH THE CRYOCOOLER WORKING FLUID, RESULTING IN INFERIOR PERFORMANCE. OUR THREE CONCEPTS ARE IMPORTANT TO NASA'S VARIOUS MISSIONS.MANY NASA PAYLOADS DEPEND ON COOLING INFRA-RED SENSORS TO TEMPERATURES ON THE ORDER OF 2 K. SUCH TEMPERATURES CAN CURRENTLY BE ATTAINED ONLY WITH REFRIGERATION THAT USES LIQUID HELIUM AS THE WORKING MEDIUM. THE PROPOSED CONCEPTS CAN REDUCE SIGNIFICANTLY THE COST OF LIQUID HELIUM IN SPACE.FOR EXAMPLE, THE COST OF PRODUCING LIQUID HELIUM ON EARTH WOULD BE DECREASED. MORE IMPORTANTLY, HELIUM CRYOCOOLERS MAY BECOME PRACTICAL IN SPACE, WHEREAS CURRENTLY THEY ARE SOIMPRACTICAL THAT HELIUM MUST BE RE-SUPPLIED FROM EARTH.