Abstract: A gas replacement method for an expander of a cryocooler, the expander including an expander cylinder, a pressure switching valve that switches a pressure inside the expander cylinder, a connection flow path from the pressure switching valve to the expander cylinder, and an expander motor that drives the pressure switching valve, includes connecting a nonflammable gas source to the connection flow path or the expander cylinder, and purging a residual gas in the expander cylinder with a nonflammable gas from the nonflammable gas source while the expander motor is stopped.

Abstract: A superconducting magnet device includes a superconducting coil; a radiation shield including a plurality of divided shield pieces disposed to surround the superconducting coil; a thermal bridge member that thermally connects the plurality of divided shield pieces to each other and is formed of a high thermal conductivity metal having a higher thermal conductivity than stainless steel; and a resistance layer that is interposed between the thermal bridge member and the divided shield pieces and has a higher electrical resistivity than the thermal bridge member.

Abstract: A cryogenic cooling system includes a gas circulation source; a cryocooler including a cryocooler stage that cools the cooling gas; an object-to-be-cooled gas flow path; a gas supply line that supplies a cooling gas from the gas circulation source via the cryocooler stage to the object-to-be-cooled gas flow path; a gas recovery line that recovers the cooling gas from the object-to-be-cooled gas flow path to the gas circulation source; at least one temperature sensor installed at a measurement location away from the object-to-be-cooled gas flow path along the gas supply line and/or a measurement location installed away from the object-to-be-cooled gas flow path along the gas recovery line; and a gas flow rate control unit that controls the gas circulation source to adjust a flow rate of the cooling gas flowing through the object-to-be-cooled gas flow path in accordance with a measured temperature at at least one measurement location.

Abstract: A superconducting magnet device includes a tubular cryostat defining a central cavity therein, a first superconducting coil set and a second superconducting coil set disposed outside the central cavity and inside the tubular cryostat, and a power supply system being capable of controlling a magnitude of a first exciting current to the first superconducting coil set and a magnitude of a second exciting current to the second superconducting coil set independently of each other. The first superconducting coil set generates a magnetic field distribution, which is convex downward on an X axis and convex upward on a Y axis when the first exciting current is supplied, in the central cavity. The second superconducting coil set generates a magnetic field distribution, which is convex upward on the X axis and convex downward on the Y axis when the second exciting current is supplied, in the central cavity.

Abstract: A cryocooler includes an expander provided with an expander motor including a motor rotary shaft, a displacer that changes a volume of an expansion space of a working gas by reciprocating linearly by the motor rotation shaft rotating, and a rotary valve that controls intake and exhaust of the working gas into the expansion space by rotating by the motor rotation shaft rotating, a pressure sensor that measures a pressure of the working gas and outputs a measurement signal indicating the measured pressure, and a controller that receives the measurement signal, detects a feature point appearing periodically in the measured pressure during an operation of the cryocooler, acquires a motor drive waveform indicating a command rotation speed of the motor rotary shaft determined to vary within one rotation of the motor rotary shaft, and outputs the motor drive waveform in synchronization with the feature point appearing periodically.

Abstract: A cryocooler includes a motion conversion mechanism that converts rotating motion output by a motor into linear reciprocating motion of a displacer and includes a first component and a second component slidably connected to each other, a measuring instrument that is connected to the motor to output time-series data indicating power consumption of the motor or a current flowing through the motor, and a processing unit that detects abrasion of a sliding surface between a first component and a second component of the motion conversion mechanism on the basis of section data including an intake start timing or an exhaust start timing in the time-series data.

Abstract: The cryocooler includes an expander motor that operates an expander of the cryocooler, an inverter that is configured to control an operation frequency of the expander motor and is operable to drive the expander motor in the steady operation at an operation frequency lower than in the cool-down operation, a current sensor that measures a current supplied from the inverter to the expander motor, and outputs a motor current signal indicating the current; and a processor that monitors the expander motor on a basis of the motor current signal in at least the steady operation.

Abstract: A cryogenic cooling system includes a gas circulation source; a cryocooler that cools a cooling gas; a cooling gas flow path that causes a cooling gas to flow from the gas circulation source to the object to be cooled; and a control device that controls the gas circulation source so as to execute initial cooling of the object to be cooled according to a prescribed flow rate pattern. The prescribed flow rate pattern is predetermined such that the cooling gas flows through the cooling gas flow path at a first average flow rate, and the cooling gas flows through the cooling gas flow path at a second average flow rate. The second average flow rate is smaller than the first average flow rate such that the cooling capacity of the cryogenic cooling system is increased.

Abstract: A cryocooler includes a second-stage cooling stage, a second cylinder which includes the second-stage cooling stage on a terminal of the second-stage cylinder, a second-stage displacer which includes a magnetic regenerator material and is accommodated in the second-stage cylinder so as to be able to reciprocate in the second-stage cylinder, and a tubular magnetic shield which is installed on the second-stage cooling stage and extends along the second-stage cylinder outside the second-stage cylinder. The magnetic shield is formed of a normal conductor and a product of an electrical conductivity in a temperature range of 10 K (Kelvin) or less and a thickness of the tubular magnetic shield is 60 MS (Mega-Siemens) to 1980 MS.

Abstract: A GM cryocooler includes a first cold head including a first displacer that is reciprocable in an axial direction, a first drive piston that drives the first displacer in the axial direction, and a first drive chamber that houses the first drive piston; a second cold head including a second displacer that is reciprocable in the axial direction, and a second cylinder that houses the second displacer; a first intake valve that is connected to both the first drive chamber and the second cylinder so as to supply working gas in parallel to the first drive chamber and the second cylinder; and a first exhaust valve that is connected to both the first drive chamber and the second cylinder so as to collect the working gas in parallel from the first drive chamber and the second cylinder.

Abstract: A cryocooler includes a motion conversion mechanism that converts rotating motion output by a motor into linear reciprocating motion of a displacer and includes a first component and a second component slidably connected to each other, a measuring instrument that is connected to the motor to output time-series data indicating power consumption of the motor or a current flowing through the motor, and a processing unit that detects abrasion of a sliding surface between a first component and a second component of the motion conversion mechanism on the basis of section data including an intake start timing or an exhaust start timing in the time-series data.

Abstract: A superconducting magnet device includes a tubular cryostat defining a central cavity therein, a first superconducting coil set and a second superconducting coil set disposed outside the central cavity and inside the tubular cryostat, and a power supply system being capable of controlling a magnitude of a first exciting current to the first superconducting coil set and a magnitude of a second exciting current to the second superconducting coil set independently of each other. The first superconducting coil set generates a magnetic field distribution, which is convex downward on an X axis and convex upward on a Y axis when the first exciting current is supplied, in the central cavity. The second superconducting coil set generates a magnetic field distribution, which is convex upward on the X axis and convex downward on the Y axis when the second exciting current is supplied, in the central cavity.

Abstract: A GM cryocooler includes a displacer that is reciprocatable in an axial direction; a displacer cylinder that houses the displacer; a drive piston that is coupled to the displacer so as to drive the displacer in the axial direction; and a piston cylinder that houses the drive piston and that includes a drive chamber of which a pressure is controlled to drive the drive piston, and a gas spring chamber which is airtightly formed with respect to the displacer cylinder and is partitioned from the drive chamber by the drive piston.

Abstract: A GM cryocooler includes a valve portion which defines a valve group including a first intake valve, a first exhaust valve, and a pressure equalizing valve. A valve rotor of the valve portion includes a rotor plane which is in surface contact with a stator plane of a valve stator. The valve rotor includes a high pressure flow path which is open to the rotor plane to form a portion of the first intake valve, a low pressure flow path which is open to the rotor plane to form a portion of the first exhaust valve, and a pressure equalization flow path which is open to the rotor plane to form a portion of the pressure equalizing valve, and the high pressure flow path, the low pressure flow path, and the pressure equalization flow path are circumferentially arranged around a valve rotation axis on the rotor plane.

Abstract: There is provided a cyclotron which accelerates a charged particle in an orbital trajectory to emit a charged particle beam. The cyclotron includes a magnetic pole that generates a magnetic field required for accelerating the charged particle, and a magnetic channel portion having a magnetic channel disposed on an outer peripheral portion of the orbital trajectory to guide the charged particle beam to an extraction trajectory and to focus the charged particle beam. The magnetic channel portion is attached to the magnetic pole.

Abstract: A cryocooler includes a second-stage cooling stage, a second cylinder which includes the second-stage cooling stage on a terminal of the second-stage cylinder, a second-stage displacer which includes a magnetic regenerator material and is accommodated in the second-stage cylinder so as to be able to reciprocate in the second-stage cylinder, and a tubular magnetic shield which is installed on the second-stage cooling stage and extends along the second-stage cylinder outside the second-stage cylinder. The magnetic shield is formed of a normal conductor and a product of an electrical conductivity in a temperature range of 10 K (Kelvin) or less and a thickness of the tubular magnetic shield is 60 MS (Mega-Siemens) to 1980 MS.

Abstract: A cryocooler includes a displacer capable of reciprocating in an axial direction, a cylinder that accommodates the displacer, a drive piston that drives the displacer in the axial direction, a drive chamber that accommodates the drive piston, a rotary valve that includes a first valve element that is one of a valve rotor rotatable around a rotary valve rotation axis and a valve stator, and a second valve element that is the other of the valve rotor and the valve stator, a reversible motor that is coupled with the rotary valve so as to rotate the rotary valve around the rotary valve rotation axis. The rotary valve includes a coupling mechanism that couples the first component and the second component with each other. The first relative angle is designed to cool the cryocooler, and the second relative angle is designed to heat the cryocooler.

Abstract: A superconducting magnet device includes compressor that compresses a refrigerant gas; a refrigerator that expands the refrigerant gas to generate coldness; a superconducting coil cooled by the refrigerator; a vacuum chamber that houses the superconducting coil; an electrode for a coil that is connected to the superconducting coil and disposed in the outside of the vacuum chamber; a heater that heats the electrode for a coil; a power supply line that connects the compressor and the refrigerator to each other and supplies electrical power from the compressor to the refrigerator; and a branch line that is branched from the power supply line to supply electrical power to the heater.

Abstract: A rotary valve unit includes a rotary valve and a reversible motor. The rotary valve operates according to a cooling valve timing for cooling a pulse tube cryocooler when the reversible motor rotates in a forward direction and is operated according to a heating valve timing for heating the pulse tube cryocooler when the reversible motor rotates in a backward direction. The cooling valve timing is designed to generate a working gas pressure oscillation in a pulse tube and apply a first phase delay to a working gas displacement oscillation in the pulse tube with respect to the working gas pressure oscillation. The heating valve timing is designed to generate the working gas pressure oscillation in the pulse tube and apply a second different phase delay to the working gas displacement oscillation in the pulse tube with respect to the working gas pressure oscillation.

Abstract: There is provided a cyclotron which accelerates a charged particle in an orbital trajectory to emit a charged particle beam. The cyclotron includes a magnetic pole that generates a magnetic field required for accelerating the charged particle, and a magnetic channel portion having a magnetic channel disposed on an outer peripheral portion of the orbital trajectory to guide the charged particle beam to an extraction trajectory and to focus the charged particle beam. The magnetic channel portion is attached to the magnetic pole.