title: Capturing relativistic wakefield structures in plasmas using ultrashort high-energy electrons as a probe.
abstract: A new method capable of capturing coherent electric field structures propagating at nearly the speed of light in plasma with a time resolution as small as a few femtoseconds is proposed. This method uses a few femtoseconds long relativistic electron bunch to probe the wake produced in a plasma by an intense laser pulse or an ultra-short relativistic charged particle beam. As the probe bunch traverses the wake, its momentum is modulated by the electric field of the wake, leading to a density variation of the probe after free-space propagation. This variation of probe density produces a snapshot of the wake that can directly give many useful information of the wake structure and its evolution. Furthermore, this snapshot allows detailed mapping of the longitudinal and transverse components of the wakefield. We develop a theoretical model for field reconstruction and verify it using 3-dimensional particle-in-cell (PIC) simulations. This model can accurately reconstruct the wakefield structure in the linear regime, and it can also qualitatively map the major features of nonlinear wakes. The capturing of the injection in a nonlinear wake is demonstrated through 3D PIC simulations as an example of the application of this new method.
authors.affiliation: Department of Engineering Physics, Tsinghua University, Beijing 100084, China.|Laser Fusion Research Center, China Academy of Engineering Physics, Mianyang, Sichuan 621900, China.|IFSA Collaborative Center, Shanghai Jiao Tong University, Shanghai 200240, China.
authors.forename: C J
authors.initials: CJ
authors.lastname: Zhang
authors.affiliation: Department of Engineering Physics, Tsinghua University, Beijing 100084, China.
authors.forename: J F
authors.initials: JF
authors.lastname: Hua
authors.affiliation: University of California, Los Angeles, California 90095, USA.
authors.forename: X L
authors.initials: XL
authors.lastname: Xu
authors.affiliation: Department of Engineering Physics, Tsinghua University, Beijing 100084, China.
authors.forename: F
authors.initials: F
authors.lastname: Li
authors.affiliation: Department of Engineering Physics, Tsinghua University, Beijing 100084, China.
authors.forename: C-H
authors.initials: CH
authors.lastname: Pai
authors.affiliation: Department of Engineering Physics, Tsinghua University, Beijing 100084, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Wan
authors.affiliation: Department of Engineering Physics, Tsinghua University, Beijing 100084, China.
authors.forename: Y P
authors.initials: YP
authors.lastname: Wu
authors.affiliation: Laser Fusion Research Center, China Academy of Engineering Physics, Mianyang, Sichuan 621900, China.
authors.forename: Y Q
authors.initials: YQ
authors.lastname: Gu
authors.affiliation: University of California, Los Angeles, California 90095, USA.
authors.forename: W B
authors.initials: WB
authors.lastname: Mori
authors.affiliation: University of California, Los Angeles, California 90095, USA.
authors.forename: C
authors.initials: C
authors.lastname: Joshi
authors.affiliation: Department of Engineering Physics, Tsinghua University, Beijing 100084, China.|IFSA Collaborative Center, Shanghai Jiao Tong University, Shanghai 200240, China.
authors.forename: W
authors.initials: W
authors.lastname: Lu