Since 1999, our company has been developing 4K pulse tube cryocoolers to cool MRI magnet systems, small superconductor magnets, SQUIDS, and X-ray detectors. The self-sealing coupling of our pulse tube cryocooler enables its valve unit to be separated from its cold head. This design reduces the time required for maintenance, and also makes the maintenance work easier since heating and coiling of the cold head become unnecessary. The vibrations from the valve unit or the valve unit can also be isolated with ease. The typical cooling capacity attained with a pulse tube cryocooler is 40 W at 45.9 K in the first stage and 0.9 W at 4.23 K in the second stage.
This paper reports the effects of compressor filling pressure and operating frequency on the cooling capacities at the first and second stage, and also presents the vibration measurements made at the cold head with a laser displacement meter.