Tailored electron bunches with smooth current profiles for enhanced transformer ratios in beam-driven acceleration

Abstract

Collinear high-gradient $\mathcal{O}(GV/m)$ beam-driven wakefield methods for charged-particle acceleration could be critical to the realization of compact, cost-efficient, accelerators, e.g., in support of TeV-scale lepton colliders or multiple-user free-electron laser facilities. To make these options viable, the high accelerating fields need to be complemented with large transformer ratios $>2$, a parameter characterizing the efficiency of the energy transfer between a wakefield-exciting "drive" bunch to an accelerated "witness" bunch. While several potential current distributions have been discussed, their practical realization appears challenging due to their often discontinuous nature. In this paper we propose several alternative current profiles which are smooth which also lead to enhanced transformer ratios. We especially explore a laser-shaping method capable of generating one the suggested distributions directly out of a photoinjector and discuss a linac concept that could possible drive a dielectric accelerator.

References in corpus (2)

• Generation of Relativistic Electron Bunches with Arbitrary Current Distribution via Transverse-to-Longitudinal Phase Space Exchange
• Formation and Acceleration of Uniformly-Filled Ellipsoidal Electron Bunches Obtained via Space-Charge-Driven Expansion from a Cesium-Telluride Photocathode

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• High efficiency uniform positron beam loading in a hollow channel plasma wakefield accelerator
• Longitudinal phase space synthesis with tailored 3D-printable dielectric-lined waveguides
• Beam shaping using an ultra-high vacuum multileaf collimator and emittance exchange beamline
• Longitudinal current profile reconstruction from wakefield response in plasmas and structures
• Drive beam sources and longitudinal shaping techniques