Patent ID: 8748854

Claim:
A method for tuning the frequency response of a nozzle assembly of a plasma generating system, the nozzle assembly configured for ejecting target material droplets, the plasma generating system comprising said nozzle assembly and a laser producing a beam irradiating the droplets at an irradiation region, a plasma producing EUV radiation, wherein the nozzle assembly comprises a nozzle having an orifice configured for ejecting a fluid and a sub-system having an electro-actuable element producing a modulation waveform having a modulation frequency to cause disturbance in the fluid to cause at least some of the droplets to coalesce prior to being irradiated, comprising: ascertaining the frequency response of the nozzle assembly, including at least one resonance frequency; modifying said nozzle assembly to cause said at least one resonance frequency to more closely match with said modulation frequency, wherein the modifying including optimizing one of a mass, a shape, or material composition of at least one component in said nozzle assembly.