A particle accelerator system, including apparatuses and methods, for producing a beam of bunched charged particles at high intensities and with minimal energy dispersion comprises a bunching section having a plurality of bunching cavities, an accelerating section having a plurality of accelerating and coupling cavities, and an electromagnetic drive subsystem having a single radio-frequency (RF) generator coupled to the accelerating section at a single location. The accelerating and bunching sections are directly coupled and share a common wall, which may have a resonant coupling cavity therein, such that charged particles bunch in the bunching section and travel through the common wall into the accelerating section where they are accelerated and exit the particle accelerator system as a beam of bunched charged particles. Preferably, a phase shift of one hundred-eighty degrees (180.degree.) (or it radians) is created between the electric fields of successive bunching cavities in the bunching section.