Devices are disclosed for generating X-rays, especially in a vacuum chamber from plasma formed by irradiating a target material with laser light, that provide convenient removal from the vacuum chamber of high-frequency-maintenance components without disturbing other components. In one configuration denoted a liquid-jet-type of X-ray generator, a nozzle (for spraying target material) and a mirror are situated in a vacuum chamber. The nozzle has a higher maintenance frequency than the mirror. A flange member is provided on an outer wall of the vacuum chamber to cover an opening in the wall. The nozzle is connected to a conduit having a base mounted to the flange member. The nozzle is removable for maintenance by detaching the flange member and withdrawing the nozzle through the opening. Thus, the highest-frequency-maintenance component, the nozzle, is removed without moving or removing any other component in the chamber, such as the mirror.