A radiation source suitable for providing radiation to a lithographic apparatus generates radiation from a plasma (12) generated from a fuel (31) within an enclosure comprising a gas. The plasma generates primary fuel debris collected as a fuel layer on a debris-receiving surface ((33a), (33b)). The debris-receiving surface is heated to a temperature to maintain the fuel layer as a liquid, and to provide a reduced or zero rate of formation gas bubbles within the liquid fuel layer in order to reduce contamination of optical surfaces (14) by secondary debris arising from gas bubble eruption from the liquid fuel layer. Additionally or alternatively, the radiation source may have a debris receiving surface positioned and/or oriented such that substantially all lines normal to the debris receiving surface do not intersect an optically active surface of the radiation source.