Controllable Interactions between Co-Propagating Laser Pulses in Underdense Plasmas*

In recent years, the generation of ultra-relativistic electron (e^-) beams via Laser-Wakefield Acceleration (LWFA) has become routine - though control of beam properties and dynamics remains problematic. With the evolution of laser technology into petawatt (10¹⁵ W) regimes, a unique opportunity arises to distribute power across multiple, co-propagating beamlets. Previous work of these experimental situations has demonstrated a large parameter space with complex interaction of induced wakefields and e^- beams. These mechanics are highly dependent on tractable parameters such as the number of beamlets, beamlet displacement, temporal delay, carrier frequency, etc.  Here, we establish an overview of several multi-beam effects and present how systematic investigation of beamlet parameters can lead to enhanced control over e^- beam generation. Particle-in-Cell (PIC) simulations support this concept, where a low-intensity, satellite beamlet co-propagating alongside a primary driver pulse can induce e^- injection when operating in plasma densities below the self-injection threshold of the driver. Promising results show control over injected bunch charge and duration. Supporting experiments for these multi-beam set-ups are further outlined for future work.