Exemplary temperature modulation methods may include delivering a gas through a purge line extending within a substrate support. The gas may be directed to a backside surface of the substrate support opposite a substrate support surface. The purge line may extend along a central axis of a shaft, the shaft being hermetically sealed with the substrate support. The substrate support may be characterized by a center and a circumferential edge. A first end of the purge line may be fixed at a first distance from the backside surface of the substrate support. The methods may include flowing the gas at a first flow rate via a flow pathway to remove heat from the substrate support to achieve a desired substrate support temperature profile.