a small , low cost , low power , and portable x - ray source that produces an x - ray flux that is sufficient to produce high quality x - ray images on suitable x - ray sensitive films . the source includes a vacuumated chamber that is filled with a heavy atomic weight gas at low pressure and an x - ray emitter . the chamber is in a magnetic field and an oscillating electric field and generates an electron cyclotron resonance plasma having a ring of energetic electrons inside the chamber . the electrons bombard the x - ray emitter which in turn produces x - ray radiation in a given direction . a pair of magnetic members generate an axisymmetric magnetic mirror trap inside the chamber . the chamber may be nested within a microwave resonant cavity and between the magnets , or the chamber and microwave cavity may be a single composite structure . the source is useful to make x - ray photographs virtually anywhere and may be battery powered .