STUDY ON AN INNOVATIVE VIBRATION-CANCELLATION METHOD FOR A PULSE TUBE CRYOCOOLER

研究了一种消除脉管制冷机冷端振动的新方法。采用直径为20 mm、长度为200 mm的不锈钢细管制作了一台模型脉管制冷机。为验证该消振方法的可行性，对模型制冷机冷台的振动进行了测量。模型制冷机是由多对管道在同一冷台上组成。当所提供的工作气体以适当的相移供应到这些对时，冷台的振动可以被抵消。制作了单管、双对管和三对管的脉管制冷机模型。与单管模型相比，六管模型在不增加任何隔振结构的情况下，振动降低了98%左右。然后，我们还制作了500片100号不锈钢网的回热器，并将这些部件安装在细管内，实现了脉管制冷机。对两组管和回热器的自消振型脉管制冷机进行了制冷功率验证。利用GM型氦压缩机、数字电路产生反相信号和电磁阀变压，将冷级冷却到最低温度168 K。在这种情况下，模型显示出约70%的振动减少。由于两台脉管制冷机的对称性是该方法的关键，因此任何非对称结构都可能影响到脉管制冷机的减振效果。

An innovative method for canceling the vibration at the cold stage of a pulse tube cryocooler has been investigated. A thin stainless tube of 20 mm in diameter and 200 mm in length was used to fabricate a model pulse tube cryocooler. The vibration of the cold stage of model cryocooler was measured for proving a method of this innovative vibration cancellation. A model cryocooler consists of multi-pairs of pipes on the same cold stage. When a presented working gas is supplied with a proper phase shift to those pairs, the vibration of the cold stage can be cancelled. We made models of the pulse tube cryocooler with a single pipe, two pairs of pipes and three pairs of pipes. Compared with the single-pipe model, the six-pipe model shows about a 98% reduction of vibration without any additional structure for vibration isolation.Then, we also made the regenerators with 500 sheets of stainless mesh # 100, and set up those components inside of the thin tube to realize the pulse tube cryocooler. The self-vibration canceling pulse tube cryocooler with two set of tube and regenerator was operated to verify cooling power. The cold stage was cooled down to 168 K as the lowest temperature by using a GM type helium compressor, digital circuits for anti-phase signal generation and the solenoid valves for pressure swing. In this condition, the model showed about a 70 % reduction of vibration. As the symmetry of two sets of pulse tube cryocooler is essential in this method, any asymmetric configuration could affect on effective vibration reduction.