Current Filamentation Instabilities of Proton Beams in Proton Driven Wakefield Accelerators

Plasma wakefield accelerators can generate electric-field gradients magnitudes larger than conventional accelerators. Using this technology, particle-physics experiments could be performed in much more compact devices.

The Advanced Wakefield Experiment (AWAKE) is a proof-of-concept proton-driven wakefield accelerator located at CERN. Seeded self-modulation, a controlled excitation of the longitudinal self-modulation instability, is exploited to modulate the proton bunch into a train of multiple smaller bunches along its axis. However, for alternative beam parameters, the electromagnetic Weibel-like beam filamentation instability could result in magnetic field amplification, perpendicular scattering, emittance growth and possibly even the formation of a collisionless shock.

Our research investigates which beam parameters are required for filamentation to dominate and whether this parameter regime is accessible to the AWAKE experiment. We present and compare results of linear theory, quasi-static simulations and full-PIC simulations.