2016/07/27 by C. Evain, E. Roussel, M. Le Parquier +6 · 1 citation
Physics and Astronomy · #physics.acc-ph
paper · pdf · doi:10.1103/physrevlett.118.054801
published as Phys. Rev. Lett. 118, 054801 (2017)
arxiv created 2016/07/27 · arxiv updated 2017/02/08
In recent synchrotron radiation facilities, the use of short (picosecond) electron bunches is a powerful method for producing giant pulses of Terahertz Coherent Synchrotron Radiation (THz CSR). Here we report on the first direct observation of these pulse shapes with a few picoseconds resolution, and of their dynamics over a long time. We thus confirm in a very direct way the theories predicting an interplay between two physical processes. Below a critical bunch charge, we observe a train of identical THz pulses (a broadband Terahertz comb) stemming from the shortness of the electron bunches. Above this threshold, a large part of the emission is dominated by drifting structures, which appear through spontaneous self-organization. These challenging single-shot THz recordings are made possible by using a recently developed photonic time stretch detector with a high sensitivity. The experiment has been realized at the SOLEIL storage ring.