Ultrarelativistic electron generation during the intense, ultrashort laser pulse interaction with clusters

Using a cluster jet containing Ar clusters, collimated relativistic electrons up to 58 MeV with an electron charge of 2.1 nC were generated by a laser–cluster interaction. The resulting spectrum does not fit a Maxwellian distribution, but is well described by a two-temperature Maxwellian. Two-dimensional particle-in-cell simulations demonstrate an important role of clusters that the higher energy electrons are injected by the laser pulse interaction with the clusters and then they gain their energy during the direct acceleration by the laser pulse, while the lower energy electrons are accelerated by the wakefield being injected during the plasma wave breaking.