Application of response surface methodology to the temperature fluctuation suppression structure in the cryostats

The cryocooler-based cryostat typically suffers from an intrinsic 200 mK temperature oscillation originating from the periodic variation of the cryocooler's working fluid. In this paper, a numerical study is performed to investigate the impact of a thermal link (a temperature fluctuation suppression structure)'s geometric parameters on a cryostat's performance. An optimization model is developed to minimize a cryostat flange's temperature fluctuation and deviation. We considered three factors during the analysis: the number of the thermal link wires n, the length of the thermal link l, and the radius of the thermal link wires r. Two primary evaluation measures are the temperature fluctuation T_p-p and the temperature deviation of the flange Ri. The results are analyzed using Response Surface Methodology. The final predicted optimum combination of geometrical parameters for the thermal link is n = 8, l = 36 mm, and r = 0.8 mm. The optimization results are in good agreement with our model, and the deviations in predicted values are less than 1.6%. The model and results presented here to optimize the thermal link provide helpful guidance for cryostat optimization in experiments.