Co-propagating beamlet arrays for augmented laser wakefield acceleration

Recently there has been interest in "structured" light to control laser-plasma interactions. Usually this is considered as single pulse spatio-spectral shaping; however, an alternate approach is redistributing the electromagnetic energy by independent co-incident lasers. Previous work demonstrated "co-parallel" pulses couple together due to the nonlinear plasma response to achieve tunable electron injection and increased charge from multiple bubbles in laser wakefield acceleration (LWFA). Here, we scale the number of pulses from a few (2 to 4) into hundreds or thousands. This is done by particle-in-cell simulations with periodic boundaries to create an efficient platform for modeling an "infinite" pulse array. From this, we introduce a novel LWFA scheme consisting of diffracting, low-energy beamlets to generate coherent quasi-linear wake excitation and electron acceleration in conventionally inaccessible regimes. For example, using 100J distributed into 1 TW pulses can create a spatially extended, broadband GeV-class electron beam of > 1 μC, with conversion efficiency over 70%. The modest laser parameters are suited for scalable kHz, ultrashort fiber arrays for unprecedented high-energy electron brilliance. This naturally leads to an electron synchrotron and bremsstrahlung radiation source readily coupled to MeV-class radiography of high energy density or industrial systems.