Electron emitter for producing planar radiation field to sterilize polyethylene terephthalate preforms used in e.g. food industry, has grid element including positionally varying electron penetrability to apply intensity profile to field

摘要

The unit has heating cathodes (1) i.e. cathode wires, producing electrons. Primary and secondary grid elements (2, 3) draw, distribute and accelerate the electrons from the cathodes. An electron emission window (5) emits the electrons after acceleration. One of the grid elements includes positionally varying electron penetrability for applying intensity profile to a radiation field. The grid elements include electron impermeable rods and electron permeable through-holes, where widths of the rods and the through-holes are positionally varied by the grid elements. An independent claim is also included for a method for producing a radiation field by an electron emitter.