Abstract. A method for measuring blackness degree of sample surface in a small cryogenic-vacuum chamber is proposed. Physical and mathematical models of the measuring unit are described. The operation temperature range for blackness degree measurement is defined by the temperature of the cryogenic screen, the film electrical heater power, and duration of heating process. It is shown that for copper samples of 1 mm thick and 2 cm diameter at consumed electric power of a few tenths of a Watt and the screen temperatures from 80 to 150 K, the minimal measurement error is achieved at the processing time from 10 to 20 minutes. The proposed method is reported to reduce the processing time for blackness measurement for two orders of magnitude as compared with measurement in stationary thermal mode. In the proposed method, the specified constant value of the power depends slightly on initial  temperature of the sample. An important advantage of the method consists in significant saving of energy consumption for the screen cryostatting due to reduction of the time of elementary measurement.

Keywords: blackness degree, surface, monotonic heating method, radiative heat exchange, cryogenic-vacuum chamber, flow-through cryostat system

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