Dynamics of laser-driven positron beam focusing*

Positron beams driven by direct laser plasma interaction are appealing for their possibility to provide astrophysics relevant conditions. To achieve required conditions, production of high-density positron jets is necessary. Here, we report dynamics of laser-driven positron beam focusing, resulting in high positron beam density by using a spherically curved target surface. Numerical modeling using the hybrid-PIC code shows positron acceleration by electric sheath field on the target surface at target normal direction resulting in ~x5 increase in local positron density for the curved target compared to the flat target case. It is also seen that additional structures attached on a target effectively change positron dynamics giving a further focusing effect. Detailed simulation results including field evolution and beam characteristics will be presented.