Collimation, compression and acceleration of isotropic hot positrons by an intense vortex laser

Laser-driven positron sources, characterized by short pulse width, small focal spot and high energy, are promising for potential applications, e.g. electron-positron collider and positron annihilation spectroscopy. However, the broad divergence angle and wide pulse width during the laser-driven positron transport are extremely unfavorable for achieving high spatiotemporal resolution. In this paper, we propose a novel method to manipulate the positrons by using a left-hand circularly-polarized Laguerre-Gaussian (LG) laser pulse. Using the LG laser with a intensity of 1.2x1021Wcm-2 and a duration of a few cycles, three-dimensional particle-in-cell simulations reveal that isotropic hot positrons can be effectively captured, collimated, compressed, and accelerated due to the unique field structure of the LG laser. A high-quality positron bunch is obtained with a peak divergence angle of 1 & LCIRC;, an average pulse duration of 0.5 fs, a maximum energy of 450 MeV, and a density of 70 times that of the initial electron source. A damping vibration model is also formulated to explain qualitatively the quality improvement of the positrons.

Automated summary

This paper proposes a novel method to manipulate positrons using a specific laser structure, enabling the capture, collimation, compression, and acceleration of positrons. High-quality positron bunches with improved features are obtained.