A robust scheme to obtain high charge (∼100 nC) relativisitic (> GeV) electron beams with PW lasers through DLA

Direct laser acceleration (DLA) has a potential to provide high-charge electron bunches exceeding energies predicted by the ponderomotive scaling. In recent years, ∼100 MeV electrons have been observed in experiments from DLA. Our calculations and particle-in-cell simulations show the path how to increase the energy and the injected charge for near-future laser technology. Maximum energy the electrons can gain depends on the laser intensity, plasma density and the width of the ion channel. For the case of luminal laser pulse propagation in plasma (e.g. low density) the theoretical analysis predicts that the maximum allowed electron energy increases with the plasma density. However, high plasma densities lead to strong dephasing and consequent decrease of the achieved electron energy. We propose how to achieve multi-GeV electrons using near-critical targets and future generation of laser pulses using relativistic laser intensities. Under such conditions, enabled by multipetawatt laser facilities, electrons could reach energies up to several GeV with hundreds of nC of charge. The high charge content within a few micrometer volume will be especially important if these beams are going to be used for QED cascade seeding or to generate gamma-rays in laser-electron collisions.