Demonstration test of gas contaminants adsorbent for space Stirling cooler

A Stirling cooler for space use must have a 5–10 year service life. The primary limitation is the degradation of cooling performance by gas contaminants, such as H₂O, CO, CO₂, O₂, and N₂. If these gas contaminants freeze in the regenerator or the displacer’s clearance seal, they can block the helium flow for heat exchange or disturb the smooth movement of the displacer. This study verified the effect of adsorbent adapted for the 20 K-class two-stage Stirling (2ST) cooler with a correlation between the cooling performance and the residual concentration of CO₂ gas contaminant. Although the 2ST cooler was stopped by a displacer stuck during initial cooling by adding CO₂ at 4990 ppm, the cooling performance was finally recovered to a reference level below 20 K when the equipped adsorbent was activated. Gas analysis showed that the residual CO₂ concentration was successfully reduced to 426 ppm, satisfying the less than 500 ppm requirement.