A system for forming a laser-sustained plasma includes a gas containment element, an illumination source configured to generate pump illumination, and a collector element configured to focus the pump illumination from the pumping source into the volume of the gas mixture in order to generate a plasma within the volume of the gas mixture that emits broadband radiation. The gas containment element may be configured to contain a volume of a gas mixture including a first gas component and a second gas component. The second gas component suppresses at least one of a portion of the broadband radiation associated with the first gas component or radiation by one or more excimers associated with the first gas component from a spectrum of radiation exiting the gas mixture.