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Development of high-precision temperature control using a

cryocooler and measurement method of thermal properties(Daiki Nakamura) (Hiroya Yamamoto)

(Yasuhiro Hasegawa)

(Ibaraki Univ.)

We describe a method for precisely controlling temperature using a Gifford–McMahoncryocooler that involves inserting fiber-reinforced-plastic dampers into a conventionalcryosystem. Temperature fluctuations in a GM cryocooler at 4.2 K are typically of theorder of 200 mK. It is particularly difficult to control the temperature of a GM cryocoolerat low temperatures. The fiber-reinforced-plastic dampers enabled us to dramaticallyreduce temperature fluctuations at low temperatures. A standard deviation of thetemperature fluctuations of 0.21 mK could be achieved when the temperature wascontrolled at 4.200 0 K using a feedback temperature control system with two heaters.Furthermore, numerical calculation was done using the 1D heat equation. Thistechnique makes it possible to control the temperature using a GM cryocooler.We constructed thermal conductivity measurement using steady state methodpreventing heat leak.

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