Longitudinal current profile reconstruction from a wakefield response in plasmas and structures

Present-day and next-generation accelerators, particularly for applications in driving wakefield-based schemes, require longitudinal beam shaping and attendant longitudinal characterization for experimental optimization. Here we present a diagnostic method which reconstructs the longitudinal beam profile at the location of the wakefield-generating source. The methods described derive the longitudinal profile of a charged particle beam solely from measurement of the time-resolved centroid energy change due to wakefield effects. As such, they are insensitive to the beam losses in post-interaction transport often found in common diagnostics. The reconstruction technique is based on a deconvolution algorithm that is fully generalizable to any analytically or numerically calculable Green’s function for the wakefield excitation mechanism. This method is shown to yield precise features in the longitudinal current distribution reconstruction. We demonstrate the accuracy and efficacy of this technique using simulations and experimental examples, in both plasmas and dielectric structures, and compare them to experimentally measured longitudinal beam profiles. The limits of resolution and applicability to relevant scenarios are also examined.