Optimization of positron acceleration by multi-PW laser pulses in plasma channels via particle-in-cell simulations

Positron acceleration in plasmas has gained great interest due to its promising future applications, such as multi-TeV electron-positron collider [1]. Self-generated fields in electron-evacuated plasma structures are, however, usually not well-suited for the positron focusing and guiding for on-axis propagation. Here, we study the direct acceleration of positrons in a plasma channel by next-generation multi-PW laser pulses, examined by means of quasi-3D particle-in-cell simulation with the OSIRIS framework. The positrons are created in the collision of the same laser pulse with an electron beam [2]. We study the conditions favorable for positron injection into the channel. We show that focusing challenges can be overcome due to the radiation reaction force and electron beam loading. Moreover, the beam charge is robust with respect to the small variations in plasma radius.

[1] Blue, B. E., et al. PRL 90.21 (2003): 214801

[2] Vranic, M. et al., SR 8.1 (2018): 1-11