The MSL Kibble Balance Weighing Mode

MSL is developing a Kibble balance for realizing the kilogram after it is redefined in terms of the Planck constant. The MSL Kibble balance has the potential to achieve an accuracy (standard uncertainty) of about 2 parts in 10⁸. It is based on twin pressure balances to simplify the alignment of the coil and magnetic field axes with each other, and with local gravity. The pressure balances also act as a force comparator in the weighing mode. This approach contrasts with other Kibble balances which use a beam balance or wheel for the force comparator.