Generation of collimated vortex gamma-rays from intense Poincaré beam–plasma interaction

• Published in: Physics of plasmas 2022-09, Vol.29 (9)
• Main Authors: Younis, D., Hafizi, B., Gordon, D. F.
• Format: Article
• Language: English
• Subjects: Angular momentum; Bremsstrahlung; Circular polarization; Elastic scattering; Electrons; Energy transfer; Gamma rays; Gaussian beams (optics); Lasers; Plasma interactions; Plasma physics; Waveguides
• ISSN: 1070-664X; 1089-7674
• DOI: 10.1063/5.0102909

We report on numerical calculations in which a multi-petawatt γ-ray beam is generated using a novel configuration based on fully structured light irradiating an overdense plasma waveguide. We analyze how the relativistic laser pulse efficiently confines and accelerates plasma electrons to GeV-scale energies and drives a quasi-static field that induces magneto-bremsstrahlung radiation. Multiphoton Compton scattering of electrons in the intense part of the laser also occurs although the radiated energy-density is comparatively lower. The emitted γ-rays carry orbital angular momentum, are highly collimated, and account for upwards of 15% of the incident field energy in one particular case. A comparison of the laser-to-particle angular momentum and energy transfer efficiencies is made between the cases of irradiation by a circularly polarized Laguerre–Gauss mode and one type of full Poincaré beam, and it is found that the latter yields an order-of-magnitude enhancement. The essential characteristics of the interaction are validated with three-dimensional particle-in-cell simulations that include quantum electrodynamical effects.