Characterization of ultraintense laser produced fast electron propagation in insulators vs. conductors by optical emission diagnostics

Abstract : The transport of an intense electron-beam produced by Ultra High Intensity laser pulses through metals and insulators has been studied by imaging with high resolution the optical emission (Optical Transition Radiation, Thermal and Cherenkov emission) due to electron transit through the targets. It is observed that if the target is an insulator the fast electron beam undergoes strong filamentation and the filaments increase in number with plastic thickness, with a characteristic growth rate and transversal scale in good agreement with analytical predictions based on electric field instabilities in the beam ionization front.