The present disclosure is directed to a system for protecting a reflective optic and/or any other surface in a plasma-based illumination system from debris by actively flowing gas against the debris flow direction. According to various embodiments, a vacuum chamber is configured to contain a target material, wherein a laser or discharge produced plasma is generated in response to an excitation of the target material. One or more outlets within the chamber are configured to receive gas flowing from a fluidically coupled gas source and further configured to actively flow the gas towards a source of debris and away from the reflective optic or any other protected surface at a controlled flow rate.