Two-beam particle acceleration method and apparatus

Method and apparatus for accelerating charged particles in a compact two-beam accelerator including a high voltage diode which generates an annular intense electron beam and a pencil-shaped secondary beam. The annular beam is modulated and functions as a driver beam for the secondary beam. A focusing magnetic field created by external focusing magnetic field coils adjusts the radius of the annular beam within a plurality of resonant cavity structures of an accelerating portion of the accelerator such that the phase slippage of the secondary beam, with reference to the co-propagated driver beam, is corrected. Correction of the phase slippage results in a secondary beam that is continuously accelerated. The external magnetic field also controls the energy of the secondary beam. Such high energy charged particles are useful in a wide variety of applications, such as medical radiation therapy, sterilization of medical equipment, industrial materials processing, inspection and industrial ion implantation.