The NIST Magnetic Suspension Mass Comparator and Precision Mass Metrology

The National Institute of Standards and Technology (NIST) magnetic suspension mass comparator will be used to facilitate the dissemination of the kilogram, realized in the 4th-generation NIST Kibble balance, from vacuum to air. This paper details the current status of the system. The primary focus is on the improvements made since CPEM 2016 concerning both random and systematic sources of error.