The high-frequency pulse tube cryocooler (HPTC) has been attracting increasing and widespread attention in the field of cryogenic technology because of its compact structure, low vibration, and reliable operation. The gas-coupled HPTC, driven by a single compressor, is currently the simplest and most compact structure. For HPTCs operating below 20 K, in order to obtain the mW cooling capacity, hundreds or even thousands of watts of electrical power are consumed, where radiation heat leakage accounts for a large proportion of their cooling capacity. In this paper, based on SAGE10, a HPTC heat radiation calculation model was first established to study the effects of radiation heat leakage on apparent performance parameters (such as temperature and cooling capacity), and internal parameters (such as enthalpy flow and gas distribution) of the gas-coupled HPTC. An active thermal insulation method of cascade utilization of the cold energy of the system was proposed for the gas-coupled HPTC. Numerical simulations indicate that the reduction of external radiation heat leakage cannot only directly increase the net cooling power, but also decrease the internal gross losses and increase the mass and acoustic power in the lower-temperature section, which further enhances the refrigeration performance. The numerical calculation results were verified by experiments, and the test results showed that the no-load temperature of the developed cryocooler prototype decreased from 15.1 K to 6.4 K, and the relative Carnot efficiency at 15.5 K increased from 0.029% to 0.996% when substituting the proposed active method for the traditional passive method with multi-layer thermal insulation materials.

高频脉冲管低温冷却器（HPTC）由于其紧凑的结构，低振动和可靠的操作而在低温技术领域引起了越来越多的关注。由单个压缩机驱动的气体耦合HPTC是目前最简单，最紧凑的结构。对于在20 K以下运行的HPTC，为了获得mW的冷却能力，要消耗数百甚至数千瓦的电功率，其中辐射热泄漏占其冷却能力的很大一部分。本文基于SAGE10，首先建立了HPTC热辐射计算模型，以研究辐射热泄漏对视在性能参数（例如温度和冷却能力）的影响，气体耦合HPTC的内部参数（例如，焓流和气体分布）。提出了一种主动热绝缘的方法，用于气体耦合HPTC的系统冷能级联利用。数值模拟表明，减少外部辐射热泄漏不仅可以直接增加净制冷量，而且还可以减少内部总损失，增加低温段的质量和声功率，从而进一步提高了制冷性能。实验验证了数值计算结果，测试结果表明，研制的低温制冷器原型的空载温度从15.1 K降至6.4 K，在15.5 K时的相对卡诺效率从0.029％升高至0。