Coherent high-power RF wakefield generation by electron bunch trains in a metamaterial structure
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Author(s) • • • • • • • • •
Lu, Xueying
Picard, Julian F.
Shapiro, Michael A.
Mastovsky, Ivan
Temkin, Richard J.
Conde, Manoel
Power, John G.
Shao, Jiahang
Wisniewski, Eric E.
Peng, Maowanghui
Date Issued
December 2019
Journal
Applied Physics Letters
Publisher
AIP
Abstract
We present an experimental study of coherent high-power wakefield generation in a metamaterial (MTM) structure at 11.7 GHz by 65 MeV electron bunch trains at the Argonne Wakefield Accelerator (AWA), following a previous experiment, the Stage-I experiment, at AWA. Both the Stage-II experiment, reported in this paper, and the Stage- I experiment were conducted using MTM structures, which are all-metal periodic structures with the period much smaller than the wavelength. Differences between the two experiments include: (1) Structure length (Stage-I 8 cm, Stage-II 20 cm); (2) Number of bunches used to excite the structure (Stage-I with 2 bunches, up to 85 nC of total charge; Stage-II with 8 bunches, up to 224 nC of total charge); (3) Highest peak power measured (Stage-I 80 MW in a 2 ns pulse, Stage-II 380 MW in a 10 ns pulse). The high-power radiofrequency (RF) pulses were generated by reversed Cherenkov radiation of the electron beam due to the negative group velocity in the MTM structures. Because the radiation is coherent, a train of bunches with a proper spacing can build up to achieve a high peak power. The observed output power levels are very promising for future applications in direct collinear wakefield acceleration or in transfer to a second accelerator for two beam acceleration.
Description
Submitted for publication in Applied Physics Letters
MIT Department
Massachusetts Institute of Technology. Plasma Science and Fusion Center
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DOI of Published Version
https://doi.org/10.1063/5.0012671