A support table to support a surface of a substrate, wherein the support table includes: a base surface substantially parallel to the surface of the substrate, a plurality of burls protruding above the base surface, each of the burls having a respective distal end and a first height above the base surface, the burls arranged such that, when the substrate is supported by the support table, the substrate is supported by the respective distal ends, and a plurality of elongate raised protrusions separated by gaps, each of the elongate raised protrusions having a second height above the base surface, wherein the elongate raised protrusions protrude above the base surface between the burls, and the second height is less than the first height; wherein the protrusions are arranged such that a plurality of the gaps are aligned to form a straight gas flow path towards an edge of the base surface.