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一、前言在计量学中建立导出单位量值标准的途径,是通过普遍承认的基本物理定律与基本物理单位建立的关系。在噪声标准中,噪声功率就是通过温度这个量来定度的。因此,精确测量终端负载的温度,对提高标准的精度十分重要。在7.5厘米低温噪声标准中,选用了铂电阻温度计和蒸汽压温度计,同时装在负载座的铜块上,可以相互比对核证,以便确保测温的准确性。由于低温噪声标准的终端负载处于液氮温度,终端负载产生的噪声功率要经过一段隔热过渡波导,才能到
I. INTRODUCTION The means of establishing the unit of measure for the derivation of units in metrology is established through the generally accepted basic laws of physics and the basic physical units. In the noise standard, the noise power is determined by the amount of temperature. Therefore, accurately measuring the temperature of the terminal load is very important to improve the accuracy of the standard. In 7.5 cm low temperature noise standards, the selection of platinum resistance thermometer and vapor pressure thermometer, while mounted on the copper block of the load seat, you can verify each other in order to ensure the accuracy of temperature measurement. Since the terminal load of the cryogenic noise standard is at liquid nitrogen temperature, the noise power produced by the terminal load goes through a section of the thermal insulation transition waveguide