Magnetizing nonlinear plasma wakefields for positron acceleration

Abstract

It is known that only a narrow plasma wakefield sliver in the electron-beam-driven blowout regime suits positron acceleration. Using 3D simulations, we show that matching the cyclotron frequency ${\omega }_c$ with the plasma frequency ${\omega }_p$ forms a stable electron column on axis, expanding the suitable phase space for positron acceleration sizably. For a plasma density $n_p=10^{16}{\text{ cm}}^{-3}$ in a 35 T field, the interval expands 4.3 times, and a witness positron beam gains 100--150 MeV over 6 cm ($1.6$--$2.5$~GeV/m) with a 92\% capture rate.