Theory and numerical simulations suggest that lasers can create doughnut plasma wakes for positron acceleration in compact plasma accelerators. One of the fundamental challenges for designing a plasma based linear collider is to accelerate positrons in non-linear plasma wakefields. Researchers have long considered that this regime, which can lead to very high accelerating fields, could not be used to accelerate positrons. Using particle-in-cell numerical simulations, EPP team member Jorge Vieira in collaboration with José Tito Mendonça from the Group for Lasers and Plasmas at IST, showed that lasers carrying angular orbital momentum excite doughnut shaped strongly non-linear plasma waves for high-energy positron acceleration. These results may then open the way for future designs of compact plasma based linear colliders in strongly non-linear regimes. More information can be found here.