Cryogenic Heat Pipe Thermal Switch

A CRYOGENIC HEAT PIPE THERMAL SWITCH (CHPTS) IS PROPOSED FOR DEVELOPMENT FOR APPLICATIONS TO 60 K OR LESS. A CHPTS OFFERS THE ADVANTAGES OF HIGH "ON" CONDUCTANCE, LOW "OFF" CONDUCTANCE, COMPACT SIXE, HEAT PIPE TRANSPORT, AND LOW PARASITIC HEAT INPUTS IN BOTH THE "ON" AND "OFF" MODES. THE METHOD PROPOSED INCORPORATES GAS CONTROLLED VARIABLE CONDUCTANCE HEAT PIPE TECHNOLOGY WITH A TEMPERATURE CONTROLLED RESERVOIR. A THERMOELECTRIC COOLER/HEATER (TED) WILL BE USED TO CONTROL THE RESERVOIR IN THE RANGE OF +80 C DEGREE TO -60 C DEGREE. THE APPROACH USES A WICKED RESERVOIR AND "SWITCHING" IS ACCOMPLISHED BY MOVING THE CONTROL GAS (E.G., HELIUM OR NEON) INTO OR OUT OF THE HEAT PIPE TO TURN IT "OFF" OR "ON" BY INCREASING OR DECREASING THE TEMPERATURE OF THE RESERVOIR. A SATURATED TWO PHASE FLUID SUCH AS AMMONIA OR AN ADSORPTION GETTER IS CONTAINED WITHIN THE RESERVOIR. THE PRESENCE OF THE SATURATED CONTROL FLUID OR GETTER IS REQUIRED TO PERFORM THE CONTROL FUNCTION WITH A SMALL RESERVOIR SIZE. AN "OFF" CONDUCTANCE OF LESS THAN 0.0025 W/C DEGREE SHOULD BE READILY ATTAINED WITH THIS DEVICE.