A fine-focusing x-ray source using carbon-nanofiber field emitter

A fine-focusing x-ray source has been constructed employing a field electron emitter prepared by growing carbon-nanofibers (CNFs) on a metal tip. The x-ray source is composed of a CNF field electron emitter, an electrostatic lens, two magnetic lenses, and a W-target for generating x-rays by electron impact. The CNFs provided field electrons with a current density of J∼5×109 A/m2, which was evaluated with the aid of Fowler–Nordheim theory. The electron beam extracted from the CNF emitter was accelerated to the energies of E=10–25 keV, and then focused by the lenses. By recording the x-ray images of test charts, the optimum resolution of the x-ray source was estimated to be approximately Dx=0.5 μm.