Cool-down acceleration of G-M cryocoolers with thermal oscillations passively damped by helium

[摘要] 4 K Gifford-McMahon cryocoolers suffer from inherent temperature oscillations which can be a problem for certain attached electronic instrumentation. Sumitomo Heavy Industries has exploited the high volumetric specific heat of super-critical He to quell these oscillations (approx. 10 dB) by strongly thermally linking a separate vessel of He to the second stage; no significant thermal resistance is added between the payload and the working gas of the cryocooler. A noticeable effect of the helium damper is to increase the cool-down time of the second stage below 10 K. For the operation of niobium-based superconducting electronics (NbSCE), a common practice is to warm the circuits above the critical temperature (∼9 K) and then cool to the operating point in order to redistribute trapped magnetic fluxons, so for NbSCE users, the time to cool from 10 K is important. The gas in the helium damper is shared between a room-temperature buffer tank and the 2nd stage vessel, which are connected by a capillary tube. We show that the total cool-down time below 10 K can be substantially reduced by introducing a combination of thermal linkages between the cryocooler and the capillary tube and in-line relief valves, which control the He mass distribution between the warm canister and cold vessel. The time to reach operating temperature from the superconducting transition has been reduced to

[发布机构] Hypres, Inc, 175 Clearbrook Rd, Elmsford; NY; 10523, United States^1;Applied Materials, Inc, 3100 Bowers Ave, Santa Clara; CA; 95054, United States^2

[效力级别] 物理学 [学科分类] 材料科学（综合）

[关键词] Critical temperatures;Electronic instrumentation;Operating temperature;Sumitomo heavy industries;Superconducting electronics;Superconducting transitions;Temperature oscillations;Thermal oscillations