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Addressing this challenge, CryoTech has introduced an innovative and cost-effective micro-miniature split Stirling cryocooler featuring a single-piston compressor and a pneumatic expander, the vibration export of which has been effectively reduced at the source by substantially decreasing the weight of the moving assemblies. For vibration-sensitive applications, the authors provide an optional Tuned Dynamic Counterbalancer featuring a linear failure-free magnetic spring. This patent-pending solution enables not only a failure-free operation of a substantially lighter device but also leads to a substantial reduction in the damping ratio, thereby additionally enhancing the vibration attenuation ratio at the driving frequency.
The authors provide a comprehensive overview of the outcomes derived from a thorough feasibility study, encompassing both theoretical analysis and full-scale experimentation.
Ruggedizing vibration sensitive components of electro-optical module using wideband dynamic absorber
An inherent limitation of this technique is that it is applicable only at the fixed boiling temperature of the chosen liquid coolant, for example, 77K for LN2. There is a need, therefore, to use other (often exotic) cryogenic liquids when calorimetry is needed at temperatures other than 77K. A further drawback is related to the transitional nature of last drop boiling, which manifests itself in development of enlarged bubbles, explosions and geysering. This results in an uneven flow rate and also affects the natural temperature gradient along the cold finger. Additionally, mass flow meters are known to have limited measurement accuracy.
The above considerations especially hold true for advanced High Operational Temperature IDDAs, typically featuring short cold fingers and working at 150K and above. In this work, we adapt the well-known technique of dual-slope calorimetry and show how accurate calorimetry may be performed by precooling the IDDA and comparing the warm-up slopes of the thermal transient processes under different trial added heat loads. Because of the simplicity, accuracy and ability to perform calorimetry literally at any temperature of interest, this technique shows good potential for replacing traditional boil-off calorimetry.
Novel concept for driving the linear compressor of a micro-miniature split Stirling cryogenic cooler
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