Tail-Wave-Assisted Positron Acceleration in Nonlinear Laser Plasma Wakefields

Relativistic laser-wakefield acceleration is characterized by an unsurpassed accelerating gradient, which very suitable for electron over short distances and could be a promising candidate next-generation compact accelerators. However, using this technique positron remains challenging because positively charged particles are commonly defocused in the structure of standard nonlinear wakefield driven ultrashort laser pulse. Here we propose numerically demonstrate scheme to accelerate externally injected beam regime where tail wave formed behind density cusps wakefield. This can provide focusing force addition longitudinal positrons. Three-dimensional particle-in-cell simulations that trapping efficiency positrons nearly 100% possible. may open simple way achieve hundreds MeV at high repetition rates with terawatt-class systems without need special modes plasma structures.