The momentum distributions of the escaping particles in the focusing and free-escape boundary simulations at different points in simulation time. In the focusing simulation, a particle will unlikely return to the shock from Z > L, so particles beyond L upstream will be considered for the momentum distributions of escaped particles. In the free-escape boundary simulations, particles that are beyond the free-escape boundary specified by Z = αL (where L = R_⊙) are considered for the momentum distributions of escaped particles.