Nakamura Daiki, Hasegawa Yasuhiro, Murata Masayuki, Yamamoto Hiroya, Tsunemi Fumiaki, Komine Takashi
Saitama University, Faculty of Engineering, 255 Shimo-Okubo, Saitama 338-8570, Japan.
Rev Sci Instrum. 2011 Apr;82(4):044903. doi: 10.1063/1.3581211.
Modeling and experiments are performed to decrease temperature fluctuation generated by the periodic motion of the displacer in a Gifford-McMahon (GM) type cryocooler within the low-temperature region. The one-dimensional heat equation allows us to show that thermal diffusivity is an essential factor to achieve much smaller temperature fluctuation, and fiber-reinforced plastic (FRP) with low thermal diffusivity makes it possible to reduce the temperature fluctuation dramatically. Based on the model, experiments are performed to vary the thickness of two FRP dampers, on the cryohead of the cryocooler and on the sample stage. As a result, the FRP dampers enable us to achieve the temperature fluctuations of only 0.7 mK, corresponding to a standard deviation of 0.25 mK, when the sample stage is maintained at 4.2000 K, even if a GM cryocooler is utilized for cooling the temperature, which introduces an initial temperature fluctuation of 282 mK at the cryohead.
开展了建模与实验，以减少吉福德 - 麦克马洪（GM）型低温制冷机低温区域内由活塞周期性运动产生的温度波动。一维热传导方程表明，热扩散率是实现更小温度波动的关键因素，而低热扩散率的纤维增强塑料（FRP）能够显著降低温度波动。基于该模型，进行了实验以改变制冷机冷头和样品台上两个FRP阻尼器的厚度。结果表明，当样品台保持在4.2000 K时，即使使用GM制冷机进行冷却（其在冷头处会引入282 mK的初始温度波动），FRP阻尼器仍能使温度波动仅为0.7 mK，对应标准偏差为0.25 mK。
