Diagnosing the dynamics of fast electron transport with self-induced magnetic fields

We offer a new method to study the transport of fast electrons in dense, hot media. The technique relies on temporal profiling of the laser induced magnetic fields and offers a unique capability to map the hot electron currents and their neutralization (or lack of it) by the return currents in the plasma. We have considered 2 media with widely different conductivities: one a conductor (Al metal) and other an insulator (glass). We report direct quantitative measurements of strong electric inhibition in insulators and turbulence induced anomalous stopping of hot electrons in conductors. (authors)