title: Nanoscale Electron Bunching in Laser-Triggered Ionization Injection in Plasma Accelerators.
abstract: Ionization injection is attractive as a controllable injection scheme for generating high quality electron beams using plasma-based wakefield acceleration. Because of the phase-dependent tunneling ionization rate and the trapping dynamics within a nonlinear wake, the discrete injection of electrons within the wake is nonlinearly mapped to a discrete final phase space structure of the beam at the location where the electrons are trapped. This phenomenon is theoretically analyzed and examined by three-dimensional particle-in-cell simulations which show that three-dimensional effects limit the wave number of the modulation to between >2k_{0} and about 5k_{0}, where k_{0} is the wave number of the injection laser. Such a nanoscale bunched beam can be diagnosed by and used to generate coherent transition radiation and may find use in generating high-power ultraviolet radiation upon passage through a resonant undulator.
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: C-H
authors.initials: CH
authors.lastname: Pai
authors.affiliation: Department of Engineering Physics, Tsinghua University, Beijing 100084, China.
authors.forename: C J
authors.initials: CJ
authors.lastname: Zhang
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: 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: Department of Engineering Physics, Tsinghua University, Beijing 100084, China.
authors.forename: J F
authors.initials: JF
authors.lastname: Hua
authors.affiliation: Department of Engineering Physics, Tsinghua University, Beijing 100084, China.|IFSA Collaborative Innovation Center, Shanghai Jiao Tong University, Shanghai 200240, China.
authors.forename: W
authors.initials: W
authors.lastname: Lu
authors.affiliation: University of California, Los Angeles, California 90095, USA.
authors.forename: W
authors.initials: W
authors.lastname: An
authors.affiliation: University of California, Los Angeles, California 90095, USA.
authors.forename: P
authors.initials: P
authors.lastname: Yu
authors.affiliation: University of California, Los Angeles, California 90095, USA.
authors.forename: C
authors.initials: C
authors.lastname: Joshi
authors.affiliation: University of California, Los Angeles, California 90095, USA.
authors.forename: W B
authors.initials: WB
authors.lastname: Mori