Development of a high average power extreme ultraviolet electric capillary discharge source

Progress continues on the development of the EUV Electric Capillary Discharge Source. Over the past year we have studied the high average power operational characteristics, used interferometry to measure the in-capillary electron density, and further reduced the debris deposition rate on plasma facing optics. A pulser capable of driving the source at up to 1 kHz was acquired and preliminary testing is in progress. EUV flux and spectral emission measurements were made for pure xenon and xenon/helium mixtures using a new electrode designed to prevent debris from depositing on multilayer optics. Finally, through improvements in capillary and electrode design and material properties coupled with the assistance of mitigation approaches, we have been able to significantly reduce the amount of debris generated by the source thereby increasing the reflectance lifetime of plasma-facing optics.