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SLAC Publication: SLAC-PUB-16864
SLAC Release Date: March 6, 2017
Observation of acceleration and deceleration in frontier gradient dielectric wakefield accelerators
O'Shea, Brendan.
There is urgent need to develop new acceleration techniques capable of exceeding gigaelectron-volt-per-meter (GeVm-1) gradients in order to enable future generations of both light sources and high energy physics experiments. To address this need, shorter wavelength (THz) accelerators based on wakefields, where an intense relativistic electron beam radiates the demanded fields directly into the accelerator structure or medium, are currently under intense investigation. This approach has yielded ... Show Full Abstract
There is urgent need to develop new acceleration techniques capable of exceeding gigaelectron-volt-per-meter (GeVm-1) gradients in order to enable future generations of both light sources and high energy physics experiments. To address this need, shorter wavelength (THz) accelerators based on wakefields, where an intense relativistic electron beam radiates the demanded fields directly into the accelerator structure or medium, are currently under intense investigation. This approach has yielded success in plasma media, with well over GeVm-1 acceleration shown. Further, plasma wakefield acceleration (PWFA) has demonstrated 50% wave energy extraction efficiency. However, due to the presence of free charges and currents in contact with the beam, plasmas also introduce potentially deleterious effects not usually found in accelerators. A promising alternative, the dielectric wakefield accelerator (DWA) under investigation here, has shown structure breakdown accelerating field limits in excess of 5 GVm-1. However, acceleration gradients in excess of 69 MeVm-1 have not yet been demonstrated,,. In a dramatic advance, we report here measured average drive beam deceleration gradients of 1.3470.020 GeVm-1 in a 15 cm long DWA, corresponding to a median energy change of over 2023 MeV in a 20.35 GeV electron beam. We further show that, when the electron bunch is divided to form a driver-witness pair, an average accelerating gradient of >320 MeVm-1 is observed, with an associated wave-energy extraction efficiency of ~80%. Moreover, such high-gradients open up research into the excitation Show Partial Abstract
  • Interest Categories: Accelerator Physics