High Repetition Rate X-ray Preionization Source

discharges. These photons can be generated by stopping 7OkeV electrons by a target made of high z material like tungsten or tantalum. In this contribution we describe the performance of an X-ray generator employing a corona plasma cathode [1]. Electrons can easily be extracted from a plasma on the surface of a dielectric. The plasma is generated by accelerating electrons, emitted from sharp edged conductors close to the dielectric, along the surface of the dielectric. These electrons will liberate and ionize atoms which are loosely bound to the dielectric surface and so a plasma is formed. Energy can be dissipated in the surface plasma because of the displacement current generated by a fast rising voltage across the capacitor formed by the plasma and an electrode at the other side of the dielectric. Because of this the plasma will spread and finally cover the dielectric surface completely forming a uniform cathode with a very low work function from which electrons can be extracted towards an anode.