Collimation of PetaWatt laser-generated relativistic electron beams propagating through solid matter

Particle-in-cell simulations aimed at developing methods to control the relativistic electron beam blowup observed in recent laser-plasma experiments are described. By radially layering vacuum gaps and/or dissimilar materials with varying ionizability, a negative radial gradient in plasma density would be formed. This gradient results in confining fields that can, in principle, confine the hot electron column to nearly the laser injection spot size. Fully kinetic ion dynamics are included, to account for heavy particle transport effects across interfaces. Potential applications include radiography, electron beam focusing, and perhaps beam collimation for fast ignition. Experiments are presently being planned to test this concept.