A CRYOCOOLER FOR SUPERCONDUCTING IMAGING SYSTEMS

能够达到液氦温度（4.5 K）的封闭循环制冷机 可以有重要的应用。 拟议的工作包括 基于孔板的四级制冷机的实验验证 脉冲管周期 设计是基于热力学模型的 制冷机循环在第一阶段的努力。 一种先进的回热器 概念，基于多孔板是需要为低温 制冷机的各个阶段。 预计总COP为5000瓦/瓦 对于制冷机，假设理想的压缩机操作。 拟议 机器应具有高可靠性，因为它没有运动部件， 低温部分的节流孔。 没有活动部件 这也意味着振动和磁性特征很小。 这是 对于涉及灵敏磁矩检测器的应用是关键的， 比如SQUID磁强计。

Closed cycle cryocoolers that can reach liquid helium temperatures (4.5 K could have important applications. The proposed effort covers the experimental demonstration of a four-stage cryocooler based on the orifice pulse-tube cycle. The design is based on a thermodynamic model of the cryocooler cycle developed in the Phase I effort. An advanced regenerator concept, based on perforated plates is required for the low temperature stages of the cryocooler. An overall COP of 5000 watt/watt is predicted for the cryocooler, assuming ideal compressor operation. The proposed machine should have high reliability since it has no moving parts or orifice restrictions in the cryogenic section. The absence of moving parts also means that the vibration and magnetic signatures are small. This is critical for applications that involve sensitive magnetic moment detectors, such as the SQUID Magnetometer.