Generation of high-yield, azimuthally spin-polarized positron beams from relativistic electrons in cone–channel targets

High-energy, high-yield structured spin-polarized positron beams have important applications in nuclear physics, high-energy physics, and information storage. However, their generation remains a significant challenge. Here, we put forward a scheme to generate these beams using a dense relativistic electron beam interacting with a gas-filled cone–channel target. The interaction induces composite focusing fields comprising the electric field from a plasma bubble and skin-layer magnetic fields from the electron beam and displacement currents. These fields compress the seed beam to ultrahigh density, thereby inducing extreme fields that enable efficient γ-photon emission and subsequent pair production, leading to a high positron yield. Furthermore, the azimuthal topology of these fields is imprinted onto the generated positrons, creating unique azimuthal polarization. Our simulations demonstrate the generation of an azimuthally polarized positron beam with a charge of 0.63 nC, a polarization approaching 60%, and an energy conversion efficiency exceeding 3%. Our method provides a highly efficient pathway for generating azimuthally polarized positrons, paving the way for their potential applications.