10 / 2023-03-13 17:04:14

Femtosecond time-resolved dynamics of fast electrons in relativistic laser-foil interactions

Fast electrons generation and transport in ultrashort intense laser-plasma interactions are essential processes for the laser energy deposition, generation of ultrafast radiation sources, ion acceleration, fast ignition approach for inertial fusion energy, etc. Diagnostics of the spatial, spectral characteristics of the fast electrons have been widely carried out. However, precisely measuring the dynamic of the fast electrons has long been a challenge since time-resolution as high as femtosecond scale is needed.

In this talk we will present femtosecond time-resolved, real-time measurements of the temporal characteristics and dynamics of fast electron beams in thin solids driven by relativistic intense laser pulses, using the self-induced terahertz transition radiation. With the highest time-resolution ever obtained, we have found that the duration of the fast electron beams is comparable to that of the driving laser pulse. We have directly visualized the fast electron recirculation in the foil, where electrons are trapped inside the self-generated electrostatic potential and rebound back and forth around the thin foil for hundreds of femtoseconds. The results should much helpful for understanding and controlling the fast electron dynamics, and further manipulating laser-driven secondary particle and radiation sources.