A cryocooler includes a first cylinder and a second cylinder, a first cooling stage, a second cooling stage, a radiation shield which is cooled by the first cooling stage, accommodates the second cooling stage, and shields the second cooling stage from radiant heat from an outside, and a temperature sensor which detects a temperature of the second cooling stage. A working gas is supplied into the first cylinder and the second cylinder to be expanded and is exhausted to the outside, an insertion hole through which an output cable of the temperature sensor passes through from an inside to an outside of the radiation shield is provided in the radiation shield, and the insertion hole is configured such that the radiant heat entering the radiation shield from the outside of the radiation shield is not directly radiated to the second cooling stage.

Provided is a thermoacoustic refrigerator including an air column pipe, a prime mover, a load, and a heat accumulation tank. An exhaust gas supplied to and discharged from the heat accumulation tank is supplied, as a heat source, to the prime mover disposed inside the air column pipe, so as to cause self-oscillation of a working gas filled in the air column pipe so that sound waves are generated. With the sound waves, the load disposed inside the air column pipe converts sound wave energy into heat energy, so as to output cold heat.

A thermoacoustic refrigeration assembly includes a resonating tube having a first end and a second end; a first mechanical oscillator at the first end; a second mechanical oscillator at the second end; and a thermoacoustic stack sandwich disposed along a length of the resonating tube through which gas travels. The stack sandwich includes a first outboard heat exchanger on a first side of the stack sandwich facing the first mechanical oscillator, a second outboard heat exchanger on a second side of the stack sandwich facing the second mechanical oscillator, and a center heat exchanger disposed between the first outboard heat exchanger and the second outboard heat exchanger.

Provided is a thermoacoustic refrigerator including an air column pipe, a prime mover, a load, and a heat accumulation tank. An exhaust gas supplied to and discharged from the heat accumulation tank is supplied, as a heat source, to the prime mover disposed inside the air column pipe, so as to cause self-oscillation of a working gas filled in the air column pipe so that sound waves are generated. With the sound waves, the load disposed inside the air column pipe converts sound wave energy into heat energy, so as to output cold heat.

There is provided a cryocooler including a cryocooler cylinder, a pressure switching valve that generates a periodic pressure fluctuation inside the cryocooler cylinder, and a sensor that measures a periodic deformation of the cryocooler cylinder, which is caused by the periodic pressure fluctuation inside the cryocooler cylinder.

A thermoacoustic refrigeration assembly includes a resonating tube having a first end and a second end; a first mechanical oscillator at the first end; a second mechanical oscillator at the second end; and a thermoacoustic stack sandwich disposed along a length of the resonating tube through which gas travels. The stack sandwich includes a first outboard heat exchanger on a first side of the stack sandwich facing the first mechanical oscillator, a second outboard heat exchanger on a second side of the stack sandwich facing the second mechanical oscillator, and a center heat exchanger disposed between the first outboard heat exchanger and the second outboard heat exchanger.

A cryogenic cooling apparatus includes: a vacuum container; a first bellows connected to a peripheral portion of an opening provided in the vacuum container; a flange provided at a tip of the first bellows on a side opposite to the opening of the vacuum container and configured to fix a refrigerator; a first sleeve connected to a peripheral edge portion of an opening of the flange, into which the refrigerator is inserted, and configured to form a first accommodation space; a first heat-transfer block provided at a tip of the first sleeve on a side opposite to the flange and thermally connected to the first cooling object by being brought into contact with a first cooling block of the refrigerator; and a second bellows formed in a part of the first sleeve and configured to expand or contract the accommodation space depending on the refrigerator inserted into the accommodation space.

There is provided a cryocooler including a cryocooler cylinder, a pressure switching valve that generates a periodic pressure fluctuation inside the cryocooler cylinder, and a sensor that measures a periodic deformation of the cryocooler cylinder, which is caused by the periodic pressure fluctuation inside the cryocooler cylinder.

According to an aspect of some embodiments of the present invention there is provided a method for converting energy. The method comprises receiving energy from an external source, using the received energy for inducing a mass exchange process to release thermodynamic energy, and converting the thermodynamic energy directly into electrical energy at sufficient amount for performing work therewith. In some embodiments of the present invention, a portion of the released energy is converted to a pressure wave, and the mechanical energy constituted by the pressure wave is converted to non-mechanical energy.

A refrigerator includes a regenerator, a low-temperature end heat exchanger, a pulse tube, a high-temperature end heat exchanger, and a phase adjustment mechanism, connected in that order. A draft tube is provided inside the regenerator, paralleling the regenerator's axis, and the draft tube can extend into the low-temperature end heat exchanger.