Demonstration of a positron beam-driven hollow channel plasma wakefield accelerator

Spencer Gessner (1) , Erik Adli (2) , James M Allen (1) , Weiming An (3, 4) , Christine I Clarke (1) , Chris E Clayton (3) , Sébastien Corde (5) , J P Delahaye (1) , Joel Frederico (1) , Selina Z Green (1) , Carsten Hast (1) , Mark J Hogan (1) , Chan Joshi (3) , Carl A Lindstrom (2) , Nate Lipkowitz (1) , Michael Litos (1) , Wei Lu (6) , Kenneth A Marsh (3) , Warren B Mori (3, 4) , Brendan O'Shea (1) , Navid Vafaei-Najafabadi (3) , Dieter Walz (1) , Vitaly Yakimenko (1) , Gerald Yocky (1)

1 SLAC - SLAC National Accelerator Laboratory
2 Department of Physics [Oslo]
3 UCLA - University of California [Los Angeles]
4 Department of Physics and Astronomy [UCLA, Los Angeles]
5 LOA - Laboratoire d'optique appliquée
6 THU - Tsinghua University [Beijing]

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 is inferred from changes in the beam energy spectrum, in good agreement with theory and particle-in-cell simulations.

Domains: Physics [physics]; Physics [physics]; Plasma Physics [physics.plasm-ph]; Physics [physics]

Spencer Gessner, Erik Adli, James M Allen, Weiming An, Christine I Clarke, et al.. Demonstration of a positron beam-driven hollow channel plasma wakefield accelerator. Nature Communications, 2016, 7, pp.11785. ⟨10.1038/ncomms11785⟩. ⟨hal-01337399⟩