Desenvolvimento de um padrão primário de corrente contínua a partir da Lei de Ohm

Abstract

Ammeters in the range between nanoampere and miliampere are very used in fundamental and applied metrology, industry, microelectronics, medical care and health. The calibration of these instruments needs calibration standards to provide a minimum quality process and traceability essential for measurement system. In Brazil, it does not exist a primary DC current standard based on Ohm ́s law, which is one of BIPM recommendations to realize the ampere. In this work, a primary DC current standard based on Ohm ́s law in range between microampere and miliampere was developed. For such implementation, it was proposed the ampere realization based on Ohm ́s law that was obtained through the integration of a standard resistor, directly calibrated against a Quantum Hall System, and Josephson Voltage Standard. This integration of systems and user interface was carried out using software in Python language, developed in this research and called Iprim. This research presents DC current measurement results obtained from voltage measurement by Josephson effect applied on the real parameters of standard resistors with traceability to the SI ohm through Quantum Hall effect samples. Relative uncertainty values between 0.5 μA/A and 367.7 μA/A were obtained for the current range between 0,1 μA and 10 mA. These results, when compared with the CMC, at BIPM, of other INMs in the world, with a minimum relative uncertainty of 2 μA/A and a maximum of 2000 μA/A, show that the developed system achieved the proposed objectives. The products generated with this research were two scientific articles, the Iprim software and the developed system.