Laser Wakefield Acceleration Driven by a Discrete Flying Focus

Laser wakefield acceleration (LWFA) may enable the next generation of TeV-scale lepton colliders. Reaching such energies will likely require multiple LWFA stages to overcome limitations on the energy gain achievable in a single stage. The use of stages, however, introduces challenges such as alignment, adiabatic matching between stages, and a lower average accelerating gradient. Here, we propose a discrete flying focus that can deliver higher energy gain in a single stage, thereby reducing the number of stages required for a target energy. A sequence of laser pulses with staggered focal points and delays drives a plasma wave in which an electron beam experiences a near-constant accelerating gradient over distances beyond those attainable with a conventional pulse. Simulations demonstrate that a discrete flying focus with a total energy of 150~J can transfer 40~GeV per electron to a 50-pC beam in a single 30-cm stage, corresponding to 50~dephasing lengths. We discuss the possibility of employing this method for positron acceleration using a Laguerre-Gaussian transverse profile.