A Switch-Controller for Improved Measurements in the NIST Magnetic Suspension Mass Comparator

We describe a switch-based control strategy implemented on a proof-of-concept version of the Magnetic Suspension Mass Comparator (MSMC) at the National Institute of Standards and Technology. The MSMC apparatus is used to compare mass artifacts held in air to mass artifacts held in vacuum, without having to remove either artifact from its respective environment; thus, eliminating the need to use empirical sorption models. This comparison is achieved by magnetically suspending the mass artifact held in air. The switch-controller utilizes a combination of a magnetic field and displacement measurement to achieve the desired robustness and stability.