Fig. 1. Effect of Dewar internal pressure on Dewar heat leakage

Fig. 2. Effect of Dewar heat leakage on the K562S (@23 ℃ & 150 K)

Fig. 3. Effect of Dewar internal pressure on cool down time

Fig. 4. Pumping law of common vacuum system

Fig. 5. Process of adsorption，diffusion and desorption of gas molecule in Dewar

Fig. 6. Structural sketch of passivation barrier layer

Fig. 7. Passivation treatment scheme for Dewar inner surface

Fig. 8. Testing Dewar pressure by warming-up method

Fig. 9. Effect of passivation treatment on Dewar outgassing rate

Fig. 10. Effect of passivation treatment on Dewar H₂ gas composition