The accuracy of the measurement basis requires the assurance of the 7 basic units of the International System of Units. The mass unit "kg" is the only one of the seven basic physical quantities that is stored and reproduced on a physical basis. In order to solve this problem, many advanced national metrology institutes have conducted research in this area and proposed several solutions. Under the support of the national "Eleventh Five-Year Plan" scientific and technological support plan key project "Research on modern metrology-based benchmarking based on quantum physics," China Institute of Metrology launched this research. According to Zhang Zhonghua, the person in charge of the project, in view of the research status of foreign countries, the research group proposed the “energy balance†program that is different from the international “power balance†scheme. Through the measurement of the Planck constant, the research team established the quality. Quantum benchmarks. At present, the research group has established the first time in the world to measure the Planck constant device by energy balance method, and carried out experimental verification. The relative standard uncertainty of the first-stage measurement Planck constant reached 7.7×10-5, which is international One of the few measurements that the metrology community has obtained.
The task force also took advantage of China's quantized Hall resistance benchmarks in the world, surpassed the core technologies of mutual energy measurement and other energy balance solutions, and solved three international problems: Successfully developed a set of mutual inductance measurement systems. The amount of mutual inductance is traced back to the quantized Hall resistance and time standard, and the measurement uncertainty of the mutual inductance test system reaches 1×10-7, which is better than the internationally published minimum uncertainty of mutual measurement precision measurement (3×10-6). Successfully developed a sampling resistor with a very small load factor, and proposed a self-calibration method for load factor, which laid the foundation for the development of techniques for tracing the mutual inductance traceable to the quantized Hall resistance and high-precision steady-state current source in the energy balance program. Foundation; Successfully developed a set of magnetic field constant current source with a stability of 3×10-7/30min and an amplitude of 250mA.
It is reported that this research has a wide range of popularization and application and industrialization prospects, will greatly improve the accuracy of China's magnetic measuring instruments, precision measuring instruments, improve the value of rare earth resource utilization, enhance the independent innovation level of science and technology, has a major economic and social benefit.
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