An ion buncher stage for a linear accelerator system is disclosed for bunching ions in an ion implantation system. The ion buncher stage may be employed upstream of one or more accelerating stages such that the loss of ions in the linear accelerator system is reduced. The invention further includes an asymmetrical double gap buncher stage, as well as a slit buncher stage for further improvement of ion implantation efficiency. Also disclosed are methods for accelerating ions in an ion implanter linear accelerator.