All-optical quasi-monoenergetic GeV positron bunch generation by twisted laser fields
Jie Zhao, Yanting Hu, Yu Lu, Hao Zhang, Li-Xiang Hu, Xing-Long Zhu, Z. M. Sheng, Ion Cristian Edmond Turcu, A. Pukhov, Fu-Qiu Shao, Tong-Pu Yu
Abstract
Abstract Generation of energetic electron-positron pairs using multi-petawatt (PW) lasers has recently attracted increasing interest. However, some previous laser-driven positron beams have severe limitations in terms of energy spread, beam duration, density, and collimation. Here we propose a scheme for the generation of dense ultra-short quasi-monoenergetic positron bunches by colliding a twisted laser pulse with a Gaussian laser pulse. In this scheme, abundant γ-photons are first generated via nonlinear Compton scattering and positrons are subsequently generated during the head-on collision of γ-photons with the Gaussian laser pulse. Due to the unique structure of the twisted laser pulse, the positrons are confined by the radial electric fields and experience phase-locked-acceleration by the longitudinal electric field. Three-dimensional simulations demonstrate the generation of dense sub-femtosecond quasi-monoenergetic GeV positron bunches with tens of picocoulomb (pC) charge and extremely high brilliance above 10 14 s −1 mm −2 mrad −2 eV −1 , making them promising for applications in laboratory physics and high energy physics.