Speaker
Description
Laser wakefield accelerators (LWFA) have produced electron beams with up to ~10 GeV of energy in tens of centimeters. In addition to producing high accelerating gradients, theory predicts the existence of linear focusing forces when an LWFA is driven in the blowout regime, where all electrons behind the laser are expelled. Such linear fields are essential for maintaining an electron beam’s emittance during acceleration. Here, we present a method for direct characterization of these fields within an LWFA driven in the blowout regime. The experiments leverage the unique terawatt CO$_2$ laser system ($\lambda \sim 9.2 \mu$m) and the 55 MeV linac-driven electron beam at the Accelerator Test Facility (ATF) of Brookhaven National Laboratory. Transmission Electron Microscopy (TEM) grids were used to create electron “beamlets”, which allowed for selective transverse illumination of the different portions of the wake. The resulting deflection and the location of the focal point of the probe beamlets can then be used to characterize the electric field strength within the wake. The analytical evaluation of the approach, supporting simulation results, and recent experimental progress will be presented and discussed.
