An electron beam emitter including a vacuum chamber having a width. An electron generator can be positioned within the vacuum chamber for generating electrons. An elongate nozzle can extend from the vacuum chamber along a longitudinal axis and have an exit window at a distal end of the nozzle. The nozzle can have a width that is less than the width of the vacuum chamber. The electron generator can be shaped and dimensioned, and positioned with the vacuum chamber to form and direct a narrow electron beam that enters and travels through the nozzle, and exits out the exit window.