In a traditional closed cycle refrigerator system, samples are mounted directly to the cold head. When the system is operated, the several micron-sized vibrations, inherent in every closed cycle system, are transmitted directly from the cold head to the samples.
Model SHI-4XG-5 Low Vibration 4 K Cryocooler Mechanical Drawing - also available with a 10 K cold head. Dimensions vary depending on cold head.
CCR-XG systems are specifically designed to minimize vibrations at the sample, while at the same time utilizing a closed cycle refrigerator and providing a sample in vacuum environment. These systems isolate the vibrations of the cold head from the sample by using helium exchange gas and a rubber bellows. Instead of being attached directly to the cold head, the sample is mounted to a stage which is not connected to the cold head, yet is cooled via helium exchange gas. This arrangement allows the sample to cool, while simultaneously reducing the vibrations. The rubber bellows connects the body of the cryostat to the cold head. When the cryostat and cold head are supported separately, little to no vibrations reach the body of the cryostat via the rubber bellows.
The Model CCS-100-XG/204N (10 K) and Model SHI-4XG-5 (<5 K) systems replace the traditional optical closed cycle sample in vacuum systems: CCS-100/204 and SHI-4-1, respectively. The exchange gas isolated versions are very similar in appearance and function to the traditional optical systems, but greatly reduce the vibrations observed at the sample.
Temperature range: < 5 K - 300 K (at sample mount)
Initial cooldown time: < 2 hours to 10 K
Power requirements: 200 VAC, 3-phase, 50/60 Hz, 2.8 kW
Cooling water requirements: ~3.3 liters/min @ 4-28 degrees C
(Specifications exclude radiational or experimental heat load, and are rated at 60 Hz)
The system includes:
- Model RDK-205E two stage cold head and water-cooled compressor
- Exchange gas vibration isolation design with flexible rubber bellows connecting cold head to cryostat
- Exchange gas valve manifold to pump out and flow helium exchange gas
- Outer vacuum shroud with electrical feedthroughs, evacuation valve, and safety pressure relief valve
- Standard optical sample holder, a heater and temperature sensor
Special model SHI-4XG-15-UHV is a true ultra high vacuum (UHV) system that can be baked out to 500 K with exchange gas vibration isolation. This system was ordered for use in scanning probe microscopy measurements. With this special system's radiation shield window configuration, it has a base temperature of 3 K.
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