Described herein are methods and systems relating to an x-ray generation system. In some embodiments, the system includes an electron beam acceleration region that generates an electron beam and accelerates electrons in the beam and a radiation generation region that (i) receives the electron beam and (ii) generates an electric field having an energy of greater than about 10E7 V/m without electrical breakdown of vacuum gaps. The electric field is configured to decelerate electrons in the electron beam sufficiently to generate x-ray energy.