Research Disclosure

摘要

This research disclosure relates to a gas detection apparatus for use in a lithographic apparatus. The gas may be water vapor. The lithographic apparatus may be, for example, an extreme ultraviolet (EUV) lithographic apparatus. The lithographic apparatus may comprise a radiation source that may be a laser produced plasma (LPP) source. For such a source, a laser system may be arranged to deposit energy via a laser beam into a fuel, such as tin (Sn), which is provided from a fuel emitter. The deposition of laser energy into (he tin creates a tin plasma at the plasma formation region. Radiation, including EUV radiation, may be emitted from the plasma during de-excitation and recombination of electrons with ions of the plasma.