Characterizing the growth of current filamentation instability using laser wakefield accelerated beams*

Relativistic plasma instabilities provide a rich and active focus of research in fields ranging from high energy astrophysics to inertial confinement fusion. Current Filamentation Instability (CFI), characterized by the formation of high-density filaments as a relativistic beam current travels through a cold background plasma, is one such instability which has had a wealth of research to understand its properties in recent years. In this work a laser wakefield accelerator produces a relativistic electron beam which traverses through a cold background plasma of controllable length. Snapshots of the growth of CFI at different times may be captured by tuning the background plasma length. These experimental results are compared to theoretical frameworks for the CFI growth rate that relate the measured filament growth to properties of the beam and background plasma. Measured results are also compared to Particle-in-Cell (PIC) simulations using the OSIRIS 4.0 PIC code.