多層断熱技術Ⅱ

―断熱性能試験用カロリメータ―

抄録

The calorimeter is used to test the thermal performance of multilayer insulation (MLI). The data obtained by the calorimeter installed in a laboratory must be utilized to estimate the thermal performance of MLI fabricated in the actual cryostat for superconducting magnets or the storage vessel for low-temperature liquefied gas. If MLI is fabricated in an actual cryostat so as to be in the state of self-compression, the non-dimensional parameter P^* of the compression pressure between the adjacent layers plays an important role as an experimental condition. In order to design a calorimeter, it is necessary to pay attention to its apparent thermal conductivity, which is lowest among all insulation materials and has extremely large anisotropy. In view of this, the MLI sample must be fabricated so that it covers the entire surface of the calorimeter test cylinder, and the cross-section of MLI at its ends must not be exposed to hot surfaces or shield plates. Some amount of distortion or small steps on the cold surface where the MLI is wrapped may cause wrinkles in the MLI; at which time it becomes impossible to determine the value of P^*. A new calorimeter utilizing a small cryo-cooler and heat-flow meter is shown. This calorimeter is expected to enable to allow experiments to proceed efficiently by eliminating the burden of handling liquefied gases, like liquid helium.