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VM(Vuilleumier)制冷机是一种直接使用热能来制冷的闭循环气体回热式制冷机,它应用气体热胀冷缩的原理,采用两个推移活塞,分别推动工质气体He在高、中、低不同温区迁移,由气体平均温度的变化来实现高温压缩、低温膨胀制冷。上海技术物理研究所研制的风冷式双级微型VM制冷机采用磁力往复直线联动装置,靠磁力传递机械能,将活塞与工质气体He完全密封在工作腔内,避免使用密封轴承,不存在一般制冷机中润滑轴承与保持工质气体纯度的矛盾,因此这种制冷机具有振动小、噪声低、磨损少、寿命长以及结构紧凑、效率高等优点。我们在样品架上增加一个加热线圈后,使控温范围为77～400K,控温精度在低温区为±0.3K,高温区为±0.2K,装上样品后从室温降到77K需要70min,加热时升温速率为
VM (Vuilleumier) refrigerator is a direct use of heat to refrigeration closed-loop gas regenerative refrigerator, which uses the principle of gas expansion and contraction, the use of two push piston, respectively, to promote the working gas He in the high, medium , Low temperature migration in different areas, from the gas temperature changes to achieve high temperature compression, low temperature expansion refrigeration. The air-cooled two-stage miniature VM refrigerator developed by Shanghai Institute of Technical Physics uses magnetic reciprocating linear linkage to transmit the mechanical energy by magnetic force to completely seal the piston and the working gas He in the working chamber and avoid the use of sealed bearings. Therefore, the refrigerator has the advantages of small vibration, low noise, less wear, long service life, compact structure and high efficiency. We add a heating coil in the sample holder, the temperature range of 77 ~ 400K, temperature control accuracy of ± 0.3K in the low temperature zone, high temperature zone is ± 0.2K, after loading the sample from room temperature to 77K need 70min, Heating rate of heating