Optimizing Channel Formation with a Co-Propagating Pre-Pulse to Improve Direct Laser Acceleration of Electrons

Direct laser acceleration (DLA) may occur when a high-intensity short-pulse laser propagates through an underdense plasma. The ponderomotive force expels electrons from regions of highest intensity to form a channel that contains transverse electric and azimuthal magnetic fields. The laser is able to efficiently couple energy to the electrons in the presence of these channel fields. Prior experiments using the OMEGA EP facility demonstrate that the effectiveness of DLA is reliant on the laser geometry, and by extension channel generation. In experiments, channel formation and the acceleration of electrons are typically accomplished using the same pulse. We use particle-in-cell simulations to investigate the use of a modest intensity laser pulse to pre-form a clean channel suitable for guiding a high-intensity laser pulse. Following the channel formation, a second, high-intensity pulse may pass through the channel to efficiently accelerate electrons through DLA. Here we will present our methods and discuss the results of the study.

This work is supported by the Department of Energy / NNSA under Award Number DE-NA0004030. The OSIRIS Consortium (UCLA and IST, Lisbon, Portugal) is acknowledged for providing access to the OSIRIS 4.0 framework. Work supported by NSF ACI-1339893.