In this article, the important physical parameters which affect the electron current and energy in electron cyclotron resonance x-ray source are discussed. The electron trajectory in an empty cylindrical cavity (TE111mode), magnetized with dc magnetic field is plotted for the electrons with and without the initial velocity. Magnetic field tapering effect on the electron acceleration and the maximum attainable energy of the electron is studied. The advantages of waveguide coupling over the coaxial coupling for exciting theTE111mode of the cavity are discussed. ©1998 American Institute of Physics.