Unveiling relativistic electron bunch microstructures and their dynamical evolutions, using photonic time-stretch

The photonic time-stretch technique allows electric field pulse shapes to be recorded with picosecond resolution, at megahertz acquisition rates. Using this strategy, we could directly record spatial patterns that spontaneously appear in relativistic electron bunches, and follow their dynamical evolution over time. We present recent results obtained using two strategies. At SOLEIL, we present the shapes of the THz pulses which are emitted by the structures, and detected far from the emission point, at the end of a beamline. At ANKA, we present how it has been possible to monitor directly the electron bunch near-field. These new types of single-shot recordings allow direct and stringent tests to be performed on electron bunch dynamical models in synchrotron radiation facilities.