Phase space dynamics of a plasma wakefield dechirper for energy spread reduction
Published in Physical Review Letters, 2019
Abstract: Plasma-based accelerators have made impressive progress in recent years. However, the beam energy spread obtained in these accelerators is still at the ∼1% level, nearly one order of magnitude larger than what is needed for challenging applications like coherent light sources or colliders. In plasma accelerators, the beam energy spread is mainly dominated by its energy chirp (longitudinally correlated energy spread). Here we demonstrate that when an initially chirped electron beam from a linac with a proper current profile is sent through a low-density plasma structure, the self-wake of the beam can significantly reduce its energy chirp and the overall energy spread. The resolution-limited energy spectrum measurements show at least a threefold reduction of the beam energy spread from 1.28% to 0.41% FWHM with a dechirping strength of ∼1 (MV/m)/(mm pC). Refined time-resolved phase space measurements, combined with high-fidelity three-dimensional particle-in-cell simulations, further indicate the real energy spread after the dechirper is only about 0.13% (FWHM), a factor of 10 reduction of the initial energy spread.
Impact: This breakthrough demonstrated the first plasma-based dechirper capable of achieving beam quality requirements for next-generation light sources and colliders, representing a crucial step toward practical applications of plasma accelerators in high-energy physics and photon science.
Recommended citation: Yipeng Wu, Jianfei Hua, Zheng Zhou, Jie Zhang, Shuang Liu, Bo Peng, Yu Fang, Zan Nie, Xiaonan Ning, Chi-Hao Pai, Yingchao Du, Wei Lu, Chaojie Zhang, Warren B. Mori, C. Joshi, "Phase space dynamics of a plasma wakefield dechirper for energy spread reduction," Phys. Rev. Lett. 122, 204804 (2019).
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