Investigating Transverse Trapping Conditions in Beam-Induced Ionization Injection in PWFAs

Plasma wakefield accelerators (PWFA) have demon-strated acceleration gradients of tens of GeV per meter. For injecting high-quality electron beams, a method called beam-induced ionization injection (B- III) is proposed. In this method, the drive beam field increases as its slice envelope oscillates to its minimum value due to the betatron oscillation and ionizes electrons from an impurity element which then forms the trailing beam. Controlling the trailing beam qualities requires an understanding of a transverse trapping mechanism. This proceeding focuses on the simulation studies of transverse phase space features of ultrashort, femtosecond electron beams injected using B-III method. The ionized electron motions are tracked in the Particle-In-Cell(PIC) simulation field maps using an in-house code called eTracks. A critical condition is discovered as a transverse trapping condition in the phase space. Investigation of single particle motion in the transverse phase space shows that the trace area is connected to the transverse adiabatic invariant.