Direct laser acceleration of electrons: energy gain optimization and application to gamma-ray sources

Abstract: 
The progress in high-power laser development enabled the construction of laser systems with a total power exceeding one petawatt. Such lasers provide extremely strong electromagnetic fields that can be used as efficient sources of high-energy radiation and relativistic electrons. An electron acceleration mechanism that allows for generating hundreds of nano-coulombs of charge is called direct laser acceleration.

These beams have a wide range of potential applications in probing strong-field QED effects, neutron generation, inertial confinement fusion and ion acceleration. In this presentation, an optimization path for the acceleration process that enables an order-of-magnitude increase in cutoff energy will be discussed.

Understanding the tradeoff between the laser intensity and spot size shows a clear direction toward transferring laser energy into electrons exceeding 1 GeV in energy with a conversion efficiency >10%. Furthermore, the theoretical description of the process in the plasma varying density regime will be presented. Such a description is essential for achieving the highest possible energies when approaching the threshold for the radiation-reaction-dominated regime. Finally, the radiated spectrum will be described, demonstrating this can be a bright source of multi-MeV photons.