Sublimation Front Temperature Irregular

Tice data fluctuate and the standard deviation of the measurements becomes larger than approx. 0.3-0.5 °C. The monitored pc, 7 sh and Tco are stable, but the pressure rise measurements change and vary as shown in Fig. 2.18.2. Most likely the valve between chamber and condenser does not close reproducibly. If the drive of the valve has been checked externally as far as possible, the run cannot be finalized automatically and hand operation should be used, if the time course of the program has been already established. 

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