Table-top laser-driven ultrashort electron and X-ray source: the CIBER-X source project

We report on the development of a new laser-driven table-top ultrashort electron and X-ray source, also called the CIBER-X source (1). X-ray pulses are produced by a three-step process which consists of the photoelectron emission from a thin metallic photocathode illuminated by 16 ps duration laser pulses at 213 nm. The e-gun is a standard Pierce diode electrode type, in which electrons are accelerated by a cw electric field of similar to 11 MV/m up to a hole made in the anode. The photoinjector produces a train of 70-80 keV electron pulses of similar to 0.5 nC and 20 A peak current at a repetition rate of 10 Hz. The electrons are then transported outside the diode along a path of 20 cm length, and are focused onto a target of thullium by magnetic fields produced by two electromagnetic coils. X-rays are then produced by the impact of electrons on the target. Simulations of geometrical, electromagnetic fields and energetic characteristics of the complete source were performed previously with the assistance of the code PIXEL1 also developed at the laboratory. Finally, experimental electron and X-ray performances of the CIBER-X source as well as its application to very low dose imagery are presented and discussed. (C) 2000 Elsevier Science B.V. All rights reserved.