Abstract: A workpiece support for supporting a disc-shaped workpiece in a vacuum chamber, comprises a support member with a support surface for carrying the workpiece. A plurality of bores extend from the support surface and through the support member. The bores communicate with a distribution chamber defined on a side of the support member which is opposite from the support surface. The distribution chamber is substantially co-extensive with the support surface and is connected to a gas feed line for supplying gas to the distribution chamber. The bores each have respective diameters which are substantially shorter than their respective lengths through the support member. In this way, gas supplied through the bores from the distribution chamber is distributed between the support surface and the workpiece as a heat transfer medium which is substantially independent from the gas flow at an inlet of each bore in the distribution chamber.