EAGER: CRYO: Actively-Controlled Fast-Switching Thermal Switch for Sub-Kelvin Cooling with Low He3 Usage

这项探索性研究的早期概念拨款（EAGER）将资助支持开发低He3使用的超低温制冷的研究。氦及其更稀有的同位素He3（其地壳丰度仅为地球氦的0.00014%）目前供应短缺，预计情况会变得更糟。目前迫切需要大幅减少氦在超低制冷应用中的使用，这是国家发展量子设备及其在计算、传感和通信中的许多应用所必需的。因此，该项目将促进科学进步，促进国家繁荣，并有助于利用这些独特的技术保障国防。目前，温度低于1°k的制冷主要局限于he3稀释冰箱，这些冰箱都不是美国制造的。磁致冷是一种低氦亚开尔文的方法，是由美国宇航局为航天实验开发的。该奖项支持基础研究，以消除磁制冷作为稀释制冷的低He3替代品的商业发展的关键技术障碍。新墨西哥大学是一所西班牙裔服务机构，该项目有机会从一个非常多样化的群体中招募和培训学生，以满足该地区需要增加劳动力的需求。亚开尔文磁制冷机是美国国家航空航天局为航天实验开发的。然而，商业开发已被证明是困难的，因为这些系统的整体复杂性和缺乏简单的设计规则来设计子系统，特别是热开关。另一个挑战是难以整合支持散热和热辐射屏蔽所需的固定温度阶段。该合同将进行基础研究，以开发一种适用于0.5K-4K温度范围的新型热开关。新开关的特点包括快速主动控制，高开关比，以及一套清晰简单的设计规则。研究目标是设计；开发制造技术；演示;并对新型热敏开关进行了表征，然后演示了使用新型热敏开关在两个恒温级之间工作的单级磁致冷。详细的建模和实验将紧密结合。该项目将使用现有的低温恒温器进行测量，并将建立在PI实验室磁制冷模拟和建模工具的广泛基础上。模型和实验的比较将增加对磁制冷参数和性能的了解，以及对包含热性能变化很大的材料的复杂热交换器几何形状的静态和动态热流的了解。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This EArly-concept Grant for Exploratory Research (EAGER) will fund research supporting the development of ultra-low temperature refrigeration with low He3 usage. Helium and its even rarer isotope He3, which has a crustal abundance of only 0.00014 percent of helium on Earth, are currently in short supply and the situation is projected to get worse. There is an urgent need to drastically reduce the usage of helium in ultra-low refrigeration applications needed for the national capability for the advancement of quantum-enabled devices and their many applications in computing, sensing, and communications. The project will thus promote the progress of science, advance the national prosperity, and help secure the national defense utilizing these unique technologies. Currently, refrigeration at temperatures below 1° Kelvin is largely limited to He3-dilution refrigerators, none of which are manufactured in the United States. Magnetic refrigeration is a low- He3 sub-Kelvin approach that has been developed for spaceflight experiments by NASA. This award supports fundamental research to remove a key technical obstacle to the commercial development of magnetic refrigeration as a low- He3 replacement for dilution refrigeration. This project has the opportunity to recruit and train students from an exceptionally diverse pool at the University of New Mexico is a Hispanic Serving Institution into an area needing an increased workforce.Sub-Kelvin magnetic refrigeration has been developed for spaceflight experiments by NASA. However, commercial development has proven difficult because of the overall complexity of these systems and the lack of simple design rules to engineer the subsystems, particularly the thermal switches. A further challenge is the difficulty of incorporating the fixed-temperature stages needed to support heat-sinking and thermal radiation shields. This award will perform fundamental research to develop a new thermal switch for the 0.5K-4K temperature range. The new switch’s features include rapid active control, high switching ratio, and a clear and simple set of design rules. Research objectives are to design; develop manufacturing techniques for; demonstrate; and characterize the new thermal switch, and then to demonstrate a single stage of magnetic refrigeration using the new switch, operating between two constant-temperature stages. Detailed modeling and experiment will be closely coupled. The project will use an existing research cryostat for measurements and will build on an extensive base of magnetic refrigeration simulation and modeling tools in the PI’s laboratory. Comparison of modeling and experiment will increase knowledge of magnetic refrigeration parameters and performance, and of static and dynamic heat flow in complex heat switch geometries containing materials with widely varying thermal properties.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.