Abstract: The invention is a refrigerant cooled rotor and an associated method and system of cooling a rotor. The rotor at issue is an at least partially hollow annular enclosure with the refrigerant housed in the enclosure. The rotor is typically used to provide a surface against which another device comes into frictional contact. The refrigerant absorbs and releases the frictional heat on the rotor surface in a continuous heat transfer cycle to limit the maximum rotor temperature. By vaporizing and condensing the refrigerant inside the rotor, the refrigerant provides a regenerative heat sink for cooling.