title: Positron Acceleration by Plasma Wakefields Driven by a Hollow Electron Beam.
abstract: A scheme for positron plasma wakefield acceleration using hollow or donut-shaped electron driver beams is studied. An annular-shaped, electron-free region forms around the hollow driver beam, creating a favorable region (longitudinal field is accelerating and transverse field is focusing) for positron acceleration. For Facility for Advanced Accelerator Experimental Tests (FACET)-like parameters, the hollow beam driver produces accelerating gradients on the order of 10  GV/m. The accelerating gradient increases linearly with the total charge in the driver beam. Simulations show acceleration of a 23-GeV positron beam to 35.4 GeV with a maximum energy spread of 0.4% and very small emittance over a plasma length of 140 cm is possible.
authors.affiliation: Max Planck Institute for Solar System Research, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany.
authors.forename: Neeraj
authors.initials: N
authors.lastname: Jain
authors.affiliation: Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742, USA.
authors.forename: T M
authors.initials: TM
authors.lastname: Antonsen
authors.affiliation: Naval Research Laboratory, Washington DC 20375-5346, USA.
authors.forename: J P
authors.initials: JP
authors.lastname: Palastro