The Plasma X-ray Source (PXS) is a secondary source of hard X-ray radiation, located in Hall E1 and driven by the L1 laser beam. In PXS, the femtosecond laser pulses, which feature a repetition rate of 1 kHz, are focused on a renewing solid-density target in a vacuum. The resulting high-intensity light in the focus ionizes the target and accelerates electrons to hundreds of kiloelectron volts (keV). These electrons penetrate the target material, where they create continuum and line x-rays. The photons are emitted from the micrometer-sized plasma volume out of the vacuum chamber through an x-ray transparent window and are focused by grazing incidence or multilayer optics onto the sample. The salient feature of the PXS is the fact that x-radiation is emitted in an ultrashort pulse with a typical temporal length of hundreds of femtoseconds (~10-13 s). Such short pulses will allow scientists to resolve the kinetics of chemical reactions on atomic scales via ultrafast hard X-ray diffraction and X-ray absorption spectroscopy techniques. The inherent synchronization of the X-ray pulse to the driving IR laser will allow scientists to use advanced optical pump-hard X-ray probe methods to study things like artificial photosynthetic systems or photoactive biological molecules.