Laser-driven Acceleration with External Injection at SINBAD

Abstract

One of the important milestones to make plasma acceleration a realistic technology for user-applications is the demonstration of bunch acceleration inside a plasma wake with minimal degradation of its energy spread and emittance. This can be achieved by means of external injection of conventionally-tailored well-characterised beams into a plasma accelerator. SINBAD (Short INnovative Bunches and Accelerators at DESY) is a proposed dedicated accelerator research and development facility at DESY where amongst other topics laser-driven wakefield acceleration (LWFA) with external injection of ultra-short bunches will be exploited. To minimise energy-spread growth during acceleration, the bunch should occupy a small fraction of the plasma wavelength. In addition it has to be longitudinally synchronised with the laser driver to high accuracy. To avoid emittance growth the transport lattice for the incoming beam has to be matched to the intrinsic beta-function of the plasma. To facilitate matching and synchronisation, acceleration at low plasma densities can be advantageous. We present a preparatory feasibility study for future plasma experiments at SINBAD using simulations with the particle-in-cell code OSIRIS [1]. Field-gradient scaling laws are presented together with parameter scans of externally injected bunch, such as its injection phase, charge and length.