Defrosting system for nitrogen@ cooled probes used in cryo=medicine

摘要

The vaporising chamber (1) is in the probe tip, while the liquefaction chamber (2) is connected by a ball-valve (9) to a gas pressure bottle (10). An expansion valve (13) is mounted in a branch pipe (12). The gas used has a triple point well below the working temperature range, and has a high latent heat of transformation on phase alteration. At low critical pressure its critical temperature is well above 0 deg. C. Nitrous oxide (N2O) can be used for defrosting.