Terahertz coherent synchrotron radiation: recent results on high repetition-rate measurements and stability control at SOLEIL

Coherent synchrotron radiation (CSR) occurs when small structures are formed inside an electron bunch, as the result of either the so-called microbunching instability, or short bunch operation. CSR is known as an intense source of terahertz radiation, with an interesting potential in user applications. However specificities of the sources still required dedicated work in order to understand and master the dynamics of the emission. Here we present recent results obtained at SOLEIL, on ultrafast measurements, modeling [1] and control. In particular we will show how new techniques (time-stretch) potentially allow time-domain spectroscopy to be performed in single-shot at high (multi-MHz) repetition rates. We will also show how feedback strategies inspired from chaos control enables to suppress the so-called microbunching instability, thus opening the way to stable CSR sources in a broad range of operation modes.