Methods and systems for realizing a high radiance x-ray source based on a high density electron emitter array are presented herein. The high radiance x-ray source is suitable for high throughput x-ray metrology and inspection in a semiconductor fabrication environment. The high radiance X-ray source includes an array of electron emitters that generate a large electron current focused over a small anode area to generate high radiance X-ray illumination light. In some embodiments, electron current density across the surface of the electron emitter array is at least 0.01 Amperes/mm2, the electron current is focused onto an anode area with a dimension of maximum extent less than 100 micrometers, and the spacing between emitters is less than 5 micrometers. In another aspect, emitted electrons are accelerated from the array to the anode with a landing energy less than four times the energy of a desired X-ray emission line.