High-angle Deflection of the Energetic Electrons by a Voluminous Magnetic Structure in Near-normal Intense Laser-plasma Interactions

• Published in: arXiv.org
• Main Authors: Peebles, J, Arefiev, A V, Zhang, S, McGuffey, C, Spinks, M, Gordon, J, Gaul, E W, Dyer, G, Martinez, M, Donovan, M E, Ditmire, T, Park, J, Chen, H, McLean, H S, Wei, M S, Krasheninnikov, S I, Beg, F N
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 04.10.2018
• Subjects: Deflection; Electron acceleration; High energy electrons; Incidence angle; Laser plasma interactions; Lasers; Magnetic structure; Particle in cell technique; Physics - Plasma Physics; Plasma; Plasma interactions
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1810.02398

The physics governing electron acceleration by a relativistically intense laser are not confined to the critical density surface, they also pervade the sub-critical plasma in front of the target. Here, particles can gain many times the ponderomotive energy from the overlying laser, and strong fields can grow. Experiments using a high contrast laser and a prescribed laser pre-pulse demonstrate that development of the pre-plasma has an unexpectedly strong effect on the most energetic, super-ponderomotive electrons. Presented 2D particle-in-cell simulations reveal how strong, voluminous magnetic structures that evolve in the pre-plasma impact high energy electrons more significantly than low energy ones for longer pulse durations and how the common practice of tilting the target to a modest incidence angle can be enough to initiate strong deflection. The implications are that multiple angular spectral measurements are necessary to prevent misleading conclusions from past and future experiments.