Unveiling the complex shapes of relativistic electrons bunches, using photonic time-stretch electro-optic sampling

Photonic time-stretch enables to record electric field pulse shapes with picosecond resolution, at megahertz acquisition rates. Using this strategy, we could record the complex spatiotemporal evolution of relativistic electron bunches circulating in storage ring accelerators. We tested two complementary approaches. At SOLEIL, we monitored the THz pulses of coherent synchrotron that are emitted by the electrons. At ANKA, we monitored directly the electron bunch near-field.