Abstract: This invention provides a superconducting magnet apparatus capable of preventing or restraining the heat invading into the apparatus and reducing the refrigeration load of an external refrigerator, at the time of changeover of a switch in transiting to a persistent current mode, and capable of quick changeover operation. In the superconducting magnet apparatus of the present invention (1), in transiting to a persistent current mode, a thermal superconducting switch (41) placed in a low-temperature domain and a mechanical switch (42) placed in a mid-temperature domain are turned on. Since the mechanical switch (42) is placed in the mid-temperature domain, even if a heat load is generated through the drive mechanism (60), it is not necessary to cool the mechanical switch to an extremely low temperature.

Abstract: This invention provides a superconducting magnet apparatus capable of preventing or restraining the heat invading into the apparatus and reducing the refrigeration load of an external refrigerator, at the time of changeover of a switch in transiting to a persistent current mode, and capable of quick changeover operation. In the superconducting magnet apparatus of the present invention (1), in transiting to a persistent current mode, a thermal superconducting switch (41) placed in a low-temperature domain and a mechanical switch (42) placed in a mid-temperature domain are turned on. Since the mechanical switch (42) is placed in the mid-temperature domain, even if a heat load is generated through the drive mechanism (60), it is not necessary to cool the mechanical switch to an extremely low temperature.

Abstract: A superconducting magnet apparatus which renders possible efficient, accurate and secure connection of a superconducting magnet current lead is provided. In the superconducting magnet apparatus of the present invention, a first current lead (21) and a second current lead (22) which compose a detachable current lead for excitation power supply are automatically attached to/detached from each other via a drive mechanism (30) using a piezoelectric ceramic. Therefore, professional skills in operation and maintenance required for this attachment/detachment operation are not necessary and the apparatus is easy to take care of. Also, no manpower is required even if a plurality of superconducting magnets are excited/demagnetized one after another, and efficient operation of the apparatus is possible. Furthermore, the piezoelectric ceramic is less subject to a magnetic field.

Abstract: A cooling apparatus comprises a pulse tube refrigerator (A) having a pressure source (1), a cold reservoir (6), a condenser (7), a pulse tube (9), a radiator (1), and a phase adjuster (12); and a low-temperature container having a liquid reservoir (21) fixed to a vacuum tank (31) through heat-insulating support members (36) and (37). The condenser (7) is fixed to a cold end (6b) of the cold reservoir (6), and is disposed in a gas phase portion (21a) of the liquid reservoir (21). A hot end of the pulse tube (9) is fixed to the vacuum tank (31) and is disposed in such a manner that a cold end (9b) of the pulse tube (9) is located lower than the hot end and is located in a liquid phase portion (21b) of the liquid reservoir (21). The cold end (9b) of the pulse tube (9) is disposed outside the liquid reservoir (21) but within the vacuum tank (31), and the cold end (9b) of the pulse tube (9) and the condenser (7) communicate with each other through piping (8).

Abstract: A pulse tube refrigerating machine, comprising a pulse tube (11) connected to a regenerator (9) and having a hot end part (11a) being heated, in which a cooling device (30), for cooling the hot side tube wall (11cd) of the pulse tube by cooling medium lower in temperature than the hot side tube wall of the pulse tube, cools the hot side tube wall (11cd) of the pulse tube by coolant flowing from the pressure source (1) of the pulse tube refrigerating machine into the regenerator (9).

Abstract: A superconducting magnet apparatus which renders possible efficient, accurate and secure connection of a superconducting magnet current lead is provided. In the superconducting magnet apparatus of the present invention, a first current lead (21) and a second current lead (22) which compose a detachable current lead for excitation power supply are automatically attached to/detached from each other via a drive mechanism (30) using a piezoelectric ceramic. Therefore, professional skills in operation and maintenance required for this attachment/detachment operation are not necessary and the apparatus is easy to take care of. Also, no manpower is required even if a plurality of superconducting magnets are excited/demagnetized one after another, and efficient operation of the apparatus is possible. Furthermore, the piezoelectric ceramic is less subject to a magnetic field.

Abstract: A method for assembling a cam follower in a rocker arm of a valve drive mechanism comprises the steps of forming through the walls of the rocker arm a first through-hole which has an inner diameter slightly larger than the outer diameter of the cam follower shaft and a second through-hole which has an inner diameter slightly smaller than the outer diameter of the cam follower shaft, and inserting the shaft into the first through-hole and temporarily holding a tip end of the shaft with the second through-hole before permanently securing the shaft to the walls of the rocker arm by caulking.