High-Energy Micro-Buncher Based on the mm-Wavelength Dielectric Structure

The proton-driven plasma wakefield acceleration is a recently proposed technique promising a GeV/m rate of acceleration to a TeV-scale energy in a single plasma stage. In order to excite high-amplitude plasma wakefields a long proton bunch from a synchrotron should be broken into a sequence of sub-mm long micro-bunches which can drive the plasma oscillations resonantly. We suggest a novel approach to produce the required train of micro-bunches using collinear wakefield acceleration in a dielectric-loaded structures. First the energy modulation is introduced into the proton beam with the help of the mm-wavelength dielectric accelerating structure. Then the energy modulation is transformed into the longitudinal micro-bunching using proton beamline with magnetic dipoles. Beam dynamics simulations were used to find the appropriate parameters of the dielectric accelerating structure, driving electron bunch and the beam focusing system.