Observation of large-angle quasimonoenergetic electrons from a laser wakefield

A relativistically intense laser pulse is focused into a helium jet and quasimonoenergetic electrons emitted at a 40 degrees angle with respect to the laser axis are observed. The average electron energy is between 1 and 2 MeV and the total accelerated charge is about 1 nC emitted in a 10 degrees cone angle. Three dimensional particle-in-cell simulations reproduce key features of the experimental results and show that the interaction between ionization heating and nonlinear cavitation wakefields is responsible for the acceleration.