title: Demonstration of a positron beam-driven hollow channel plasma wakefield accelerator.
abstract: Plasma wakefield accelerators have been used to accelerate electron and positron particle beams with gradients that are orders of magnitude larger than those achieved in conventional accelerators. In addition to being accelerated by the plasma wakefield, the beam particles also experience strong transverse forces that may disrupt the beam quality. Hollow plasma channels have been proposed as a technique for generating accelerating fields without transverse forces. Here we demonstrate a method for creating an extended hollow plasma channel and measure the wakefields created by an ultrarelativistic positron beam as it propagates through the channel. The plasma channel is created by directing a high-intensity laser pulse with a spatially modulated profile into lithium vapour, which results in an annular region of ionization. A peak decelerating field of 230 MeV m(-1) is inferred from changes in the beam energy spectrum, in good agreement with theory and particle-in-cell simulations.
authors.affiliation: SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors.forename: Spencer
authors.initials: S
authors.lastname: Gessner
authors.affiliation: Department of Physics, University of Oslo, 0316 Oslo, Norway.
authors.forename: Erik
authors.initials: E
authors.lastname: Adli
authors.affiliation: SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors.forename: James M
authors.initials: JM
authors.lastname: Allen
authors.affiliation: Department of Electrical Engineering, University of California-Los Angeles, Los Angeles, California 90095, USA.|Department of Physics and Astronomy, University of California-Los Angeles, Los Angeles, California 90095, USA.
authors.forename: Weiming
authors.initials: W
authors.lastname: An
authors.affiliation: SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors.forename: Christine I
authors.initials: CI
authors.lastname: Clarke
authors.affiliation: Department of Electrical Engineering, University of California-Los Angeles, Los Angeles, California 90095, USA.
authors.forename: Chris E
authors.initials: CE
authors.lastname: Clayton
authors.affiliation: LOA, ENSTA ParisTech, CNRS, Ecole Polytechnique, Université Paris-Saclay, 91762 Palaiseau, France.
authors.forename: Sebastien
authors.initials: S
authors.lastname: Corde
authors.affiliation: SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors.forename: J P
authors.initials: JP
authors.lastname: Delahaye
authors.affiliation: SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors.forename: Joel
authors.initials: J
authors.lastname: Frederico
authors.affiliation: SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors.forename: Selina Z
authors.initials: SZ
authors.lastname: Green
authors.affiliation: SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors.forename: Carsten
authors.initials: C
authors.lastname: Hast
authors.affiliation: SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Hogan
authors.affiliation: Department of Electrical Engineering, University of California-Los Angeles, Los Angeles, California 90095, USA.
authors.forename: Chan
authors.initials: C
authors.lastname: Joshi
authors.affiliation: Department of Physics, University of Oslo, 0316 Oslo, Norway.
authors.forename: Carl A
authors.initials: CA
authors.lastname: Lindstrøm
authors.affiliation: SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors.forename: Nate
authors.initials: N
authors.lastname: Lipkowitz
authors.affiliation: SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Litos
authors.affiliation: IFSA Collaborative Innovation Center, Department of Engineering Physics, Tsinghua University, Beijing 100084, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Lu
authors.affiliation: Department of Electrical Engineering, University of California-Los Angeles, Los Angeles, California 90095, USA.
authors.forename: Kenneth A
authors.initials: KA
authors.lastname: Marsh
authors.affiliation: Department of Electrical Engineering, University of California-Los Angeles, Los Angeles, California 90095, USA.|Department of Physics and Astronomy, University of California-Los Angeles, Los Angeles, California 90095, USA.
authors.forename: Warren B
authors.initials: WB
authors.lastname: Mori
authors.affiliation: SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors.forename: Brendan
authors.initials: B
authors.lastname: O'Shea
authors.affiliation: Department of Electrical Engineering, University of California-Los Angeles, Los Angeles, California 90095, USA.
authors.forename: Navid
authors.initials: N
authors.lastname: Vafaei-Najafabadi
authors.affiliation: SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors.forename: Dieter
authors.initials: D
authors.lastname: Walz
authors.affiliation: SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors.forename: Vitaly
authors.initials: V
authors.lastname: Yakimenko
authors.affiliation: SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors.forename: Gerald
authors.initials: G
authors.lastname: Yocky