The Design and Development of a Tabletop Kibble Balance at NIST

On November 16, 2018, the 26th General Conference on Weights and Measures voted unanimously to revise the International System of Units from a system built on seven base units to one built on seven defining constants and will officially become effective on May 20, 2019, or World Metrology Day. More specifically, the unit of mass, the kilogram, will be realized via a fixed value of the Planck constant h and a Kibble balance (KB) serves as one method of achieving this. Over the past few decades, national metrology institutes around the world have developed KBs, the majority aimed at realizing the unit of mass at the 1-kg level with uncertainties on the order of a few parts in 10
⁸
. However, upon fixing the Planck constant, mass can be directly realized at any level, deeming the kilogram only a historically unique benchmark. At the National Institute of Standards and Technology, a tabletop-sized Kibble balance (KIBB-g1) designed to operate at the gram-level range with uncertainties on the order of a few parts in 10
⁶
is currently under development.