The Kibble balance is an apparatus that will be used to realise the kilogram after its redefinition in May 2019 based on a fundamental constant – the Planck constant. It compares the gravitational force on a kilogram mass with the electromagnetic force on a current-carrying coil moving in a strong permanent magnetic field. By accurately measuring the induced voltage, current, coil velocity (via position and time), local gravity, and force differences, a Kibble balance can relate a standard weight mass value to the Planck constant with an uncertainty of 20 parts per billion.
MSL is currently in the process of constructing a Kibble balance. There are several Kibble balances around the world, and their designs usually come in the form of beam balances or mass comparators that use pivots. MSL’s Kibble balance is the only one that uses a twin pressure balance with a differential pressure sensor as the force comparator. In essence, the readings from the differential pressure sensor will give information on how well the gravitational and electromagnetic forces are balanced. The advantages of this design are that it is less complex mechanically and its size is relatively small compared to other Kibble balances.
Source: The Kiwi Kibble Balance | Measurement Standards Laboratory
