| Summary: | Detailed experimental measurements are presented concerning the propagation of space-charge waves of varying amplitudes in an intense, charged-particle beam. A short perturbation to the density profile is applied at the electron gun, and both current and mean energy profiles are measured at two locations downstream. The measurements are compared to predictions of a linear 1D cold-fluid model, and self-consistent particle-in-cell simulations. For sufficiently small perturbation amplitudes, the experiment, simulation, and 1D theory agree. For larger amplitudes, the simulation begins to diverge from theoretical predictions due to nonlinear effects. Experimental observations for large-amplitude perturbations differ markedly from either theory or simulation. With the aid of simulations with mismatched and misaligned beams, this departure of experiments from predictions is demonstrated to be caused by the loss of beam current due to scraping aided by the larger radius of the perturbation.
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