Apparatus and method for establishing a temperature gradient, comprising at least one gas-tight working space having a first boundary layer that is connected to a first electrode and a second boundary layer that is connected to a second electrode, wherein when an electric voltage is applied between the first electrode and the second electrode in the working space, an electric field can be produced between the first boundary surface and the second boundary surface, and wherein a distance between the first boundary surface and the second boundary surface is less than 5000 nm, wherein the first boundary surface comprises at least one field-enhancement device, in particular a peak, so that if an electric voltage is applied to the electrodes, a field strength of the electric field in a region of the field-enhancement device is greater than an average field strength of the electric field in the working space.

A heat pump system is provided that uses MCM to provide for heating or cooling. The heat pump can include one or more stages of MCM, each stage having an original peak Curie temperature. In the event the magneto caloric response of one or more stages of MCM degrades, the present invention provides for operating the heat pump system so that one or more stages of MCM are held at a different temperature from the original peak Curie temperature so as to restore the MCM to its original peak Curie temperature or to within a certain interval thereof. The present invention can be used with e.g., an appliance, air-conditioning systems (heating or cooling), or other devices using such a heat pump system as well.

The first and second media are coupled via evanescent waves generated by surface phonon polaritons thermally excited on surfaces of the first and second media. First and second media made of the same material are disposed with a gap formed between for cutting off thermal conduction and the heat transfer between them is performed via the thermally excited evanescent waves. A third medium is provided on a surface of the first medium on a side toward the second medium. Heat flux flows from the second medium to the first medium in a first state wherein the second medium has a first temperature T.sub.H and the first medium has a second temperature T.sub.L lower than the T.sub.H differ in intensity from heat flux which flows from the first to the second medium in a second state wherein the first medium has the T.sub.H and the second medium has the T.sub.L.

A thermal stabilization system stabilizes inertial measurement unit (IMU) performance by reducing or slowing operating variations over time of the internal temperature. More specifically, a thermoelectric heating/cooling device operates according to the Peltier effect, and uses thermal insulation and a mechanical assembly to thermally and mechanically couple the IMU to the thermoelectric device. The thermal stabilization system may minimize stress on the IMU and use a control system to stabilize internal IMU temperatures by judiciously and bidirectionally powering the thermoelectric heating/cooling device. The thermal stabilization system also may use compensation algorithms to reduce or counter residual IMU output errors from a variety of causes such as thermal gradients and imperfect colocation of the IMU temperature sensor with inertial sensors.

A Gifford-McMahon cryogenic refrigerator comprises a reciprocating displacer within a refrigeration volume. The displacer is pneumatically driven by a drive piston within a pneumatic drive volume. Pressure in the pneumatic drive volume is controlled by valving that causes the drive piston to follow a programmed displacement profile through stroke of the drive piston. The drive valving may include a proportional valve that provides continuously variable supply and exhaust of drive fluid. In a proportionally controlled feedback system, the valve into the drive volume is controlled to minimize error between a displacement signal and a programmed displacement profile. Valving to the warm end of the refrigeration volume may also be proportional. A passive force generator such as a mechanical spring or magnets may apply force to the piston in opposition to the driving force applied by the drive fluid.

A Gifford-McMahon cryogenic refrigerator comprises a reciprocating displacer within a refrigeration volume. The displacer is pneumatically driven by a drive piston within a pneumatic drive volume. Pressure in the pneumatic drive volume is controlled by valving that causes the drive piston to follow a programmed displacement profile through stroke of the drive piston. The drive valving may include a proportional valve that provides continuously variable supply and exhaust of drive fluid. In a proportionally controlled feedback system, the valve into the drive volume is controlled to minimize error between a displacement signal and a programmed displacement profile. Valving to the warm end of the refrigeration volume may also be proportional. A passive force generator such as a mechanical spring or magnets may apply force to the piston in opposition to the driving force applied by the drive fluid.

A mechano-caloric heat pump includes a mechano-caloric stage, an elongated lever arm pivotable about a point, and a motor is operable to rotate a cam. The elongated lever arm is coupled to the mechano-caloric stage proximate a first end portion of the elongated lever arm and to the cam proximate a second end portion of the elongated lever arm such that the motor is operable to stress the mechano-caloric stage via pivoting of the elongated lever arm as the cam rotates.

A Gifford-McMahon cryogenic refrigerator comprises a reciprocating displacer within a refrigeration volume. The displacer is pneumatically driven by a drive piston within a pneumatic drive volume. Pressure in the pneumatic drive volume is controlled by valving that causes the drive piston to follow a programmed displacement profile through stroke of the drive piston. The drive valving may include a proportional valve that provides continuously variable supply and exhaust of drive fluid. In a proportionally controlled feedback system, the valve into the drive volume is controlled to minimize error between a displacement signal and a programmed displacement profile. Valving to the warm end of the refrigeration volume may also be proportional. A passive force generator such as a mechanical spring or magnets may apply force to the piston in opposition to the driving force applied by the drive fluid.

A multi-stage sodium heat engine is provided to convert thermal energy to electrical energy, the multi-stage sodium heat engine including at least a first stage, a second stage, and an electrical circuit operatively connecting the first stage and the second stage with an electrical load. One or more methods of powering an electrical load using a multi-stage sodium heat engine are also described.

A Gifford-McMahon cryogenic refrigerator comprises a reciprocating displacer within a refrigeration volume. The displacer is pneumatically driven by a drive piston within a pneumatic drive volume. Pressure in the pneumatic drive volume is controlled by valving that causes the drive piston to follow a programmed displacement profile through stroke of the drive piston. The drive valving may include a proportional valve that provides continuously variable supply and exhaust of drive fluid. In a proportionally controlled feedback system, the valve into the drive volume is controlled to minimize error between a displacement signal and a programmed displacement profile. Valving to the warm end of the refrigeration volume may also be proportional. A passive force generator such as a mechanical spring or magnets may apply force to the piston in opposition to the driving force applied by the drive fluid.