Multistage Positron Acceleration by an Electron Beam-Driven Strong Terahertz Radiation

Laser-plasma accelerators (LPAs) have been demonstrated as one of the candidates for traditional accelerators and have attracted increasing attention due to their compact size, high acceleration gradients, low cost, etc. However, LPAs for positrons still face many challenges, such as the beam divergence controlling, large energy spread, and complicated plasma backgrounds. Here, we propose a possible multistage positron acceleration scheme for high energy positron beam acceleration and propagation. It is driven by the strong coherent THz radiation generated when an injected electron ring beam passes through one or more solid targets. Multidimensional particle-in-cell simulations demonstrated that each acceleration stage is able to provide nearly 200 MeV energy gain for the positrons. Meanwhile, the positron beam energy spread can be controlled within 2%, and the beam emittance can be maintained during the beam acceleration and propagation. This may attract one's interests in potential experiments on both large laser facilities and a traditional accelerator together with a laser system.

Automated summary

Laser-plasma accelerators (LPAs) are considered as an alternative to traditional accelerators due to their compact size, high acceleration gradients, and low cost. However, there are still challenges for LPAs in accelerating positrons, such as beam divergence control, energy spread, and plasma backgrounds. In this study, a multistage positron acceleration scheme driven by coherent THz radiation is proposed for high energy positron beam acceleration and propagation. Particle-in-cell simulations show that each acceleration stage can provide nearly 200 MeV energy gain for positrons, while controlling energy spread within 2% and maintaining beam emittance. This research may pave the way for potential experiments using large laser facilities and traditional accelerators combined with laser systems.