RADIATION SOURCE

A radiation source includes a nozzle configured to direct a stream of fuel droplets along a trajectory towards a plasma formation location; a laser configured to output laser radiation, the laser radiation directed at the fuel droplets at the plasma formation location to generate, in use, a radiation generating plasma; and a catch configured to catch fuel droplets that pass the plasma formation location. The catch includes a container configured to contain a fluid; a driver configured to drive the fluid, to cause the fluid to move; the catch being configured such that the fuel droplets are incident on that moving fluid.