Ultrafast electron probing of extreme magnetic fields

Generation of extremely strong magnetic fields (> 0.1 MT) is anticipated during ultra-high intensity laser-solid interactions at next-generation facilities, such as ZEUS laser system at the University of Michigan. Laboratory experiments using these extreme fields can explore the fundamental physics of relativistic, highly magnetized plasmas and create conditions relevant to energetic astrophysical phenomena. However, measuring such magnetic fields poses a significant challenge for commonly used techniques like proton deflectometry as caustic formation and trajectory crossing will prevent accurate retrieval of the field profile. This work investigates the application of GeV-class electron beams from laser-wakefield accelerators for ultrafast probing of extreme magnetic fields. In addition to practical consideration of beam emittance, divergence, and energy spread, the impact of quantum-electrodynamics (QED) effects as the relativistic beam interacts with the strong fields will be presented.