The field of Fast Electron Transport is the study of how very high current beams of MeV electrons propagate through solids and dense plasmas in ultraintense laser-matter interactions.
The fast electron current densities typically reach magnitudes of 1016Am-2, and this would rapidly generate a self-stopping electric field were it not for effective current cancellation through the drawing of a background return current.
Since the background solid or plasma is resistive, a substantial electric field is established to draw the return current. In turn, Faraday’s law indicates that this must lead to the generation magnetic fields.
There are therefore three considerations: the role of electric fields, the role of magnetic fields, and the role of collisions. The role of magnetic fields is particularly important as this determines whether a beam will filament, collimate, or not.
A collimated beam will deliver a considerable amount of energy to a much smaller area. This can have considerable implications for both Fast Ignition and Proton Acceleration.
