Electron-beam driven dielectric wakefield accelerator experiments in the terahertz regime

Abstract

Bunch profile shaping using beam self-wakefields in a dielectric structure AIP Conference Proceedings 1777, 070002 (2016) Abstract. In recent years, there has been rapid experimental progress on using the self-¿elds of electron beams to drive accelerating gradients in dielectric lined cavities. The extension to sub-mm scaled cavities, producing terahertz frequencies, has allowed an accessible region to study high-gradient structures in many advanced accelerator facilities. In this paper, we present a broad review of such results as they pertain to dielectric wake¿eld acceleration (DWA). Issues that are discussed include the examination of breakdown in such structures and materials, as well as studies of in-line spectra generated by coherent Cherenkov radiation, which, for appropriate geometries, produce narrowband, tunable terahertz radiation. We examine measurements of higher-order mode excitations in these structures, which provide a novel characterization method as well as a tunable source of terahertz radiation. We describe DWA measurements including wake¿eld mapping, selective resonant mode excitation, and observation of energy modulation and acceleration made possible by electron beam manipulation schemes, such as drive-witness, pulse-train, and ramped beam generation. We present alternate materials and geometries such as 1D and 3D photonic-like structures. Finally, we conclude with preliminary results from the initial DWA experimental runs at the SLAC FACET facility.

Roadmap for Structure-based Wakefield Accelerator (SWFA) R&D and its challenges in beam dynamics

“…This condition may not be easy to achieve using conventional electron guns that provide an initial emittance of ∼ 1 μm. These requirements may be a reason to study new electron gun concepts (e.g., Trojan horse [57], capillary Trojan horse [58], TBA-based gun, etc. ), and a flat-beam transform for these new concepts.…”

Narrow-band impedance of a round metallic pipe with a low conductive thin layer

“…The study of the new type of the slowly traveling wave structures is driven by the development of both novel coherent radiation sources [1][2][3][4] and advanced acceleration concepts [5][6][7][8][9]. The disc-or dielectric-loaded structures are the most known slowly traveling wave structures that are characterized by the infinite number of excited modes [10][11][12][13].…”