Embodiments of substrate processing equipment and rotatable substrate supports incorporating the same are provided herein. In some embodiments, the substrate support may include a pedestal having a substrate receiving surface, a shaft having an upper end, a lower end, and a central opening, where the shaft is coupled to the pedestal at the upper end, a hub circumscribing the shaft, where the shaft is rotatable with respect to the hub, and where the hub includes a first port that extends from an outer surface of the hub to a volume between the hub and the shaft, and a ferrofluid sealing assembly disposed between the hub and the shaft.