A device is disclosed herein which may include a plasma generating system comprising a source of target material droplets and a laser producing a beam irradiating the droplets at an irradiation region, the plasma producing EUV radiation, wherein the droplet source comprises a fluid exiting an orifice and a sub-system producing a disturbance in the fluid which generates droplets having differing initial velocities causing the spacing between at least some adjacent droplets to decrease as the droplets travel to the irradiation region.