First observations of dispersive shock waves from the KdV equation in an electron beam

We present the first experimental observation of dispersive shock waves (DSWs) in an electron beam. Using the University of Maryland Electron Ring (UMER), a 10 keV electron beam was perturbed with a localized beam velocity dip. The resulting current profiles evolve into oscillatory structures consistent with dispersive shock behavior governed by the Korteweg–de Vries (KdV) equation. These results are predicted by particle-in-cell simulations using the WARP code. The observed dynamics open new avenues for studying nonlinear longitudinal phenomena in intense beam systems.