Abstract: In a gas injection type plasma X-ray source, a through hole communicated with vacuum is provided in each one of a pair of plasma-forming electrodes. This leads to a decrease in the dose of charged particles, a high temperature gas, etc. reflected from the upper electrode and inflicting damage on an X-ray extraction window. Accordingly, the thickness of the X-ray extraction window can be so decreased as to raise the X-ray extraction efficiency. Besides, evacuation of a space between the electrodes can be quickened. Accordingly, X-ray emission can be effected at a high repetition frequency. When the normal line direction of the electrode is inclined relative to the direction of the X-ray extraction, the effects mentioned above are enhanced.

Abstract: A gas injection type plasma X-ray source has a gas plenum for storing a discharging gas at a pressure in the range of 150 Torr and 1000 Torr, the stored gas being injected between a pair of electrodes through a gas valve. The electrodes are opposed to each other in a vacuum vessel, so that a gas jet for the production of a plasma is formed. A voltage is applied between the electrodes, so that a discharge plasma is produced between said electrodes. A linear plasma with a high temperature and a high density is produced by the pinch of the plasma due to its own magnetic field produced by the current flowing through the plasma, so that X-rays are emitted from the linear plasma. The X-ray source has a high conversion efficiency and a high discharge timing margin, and accordingly the stability and reproducibility of discharges are improved and the X-ray output is increased.