Observations of microbunching instabilities from a THz port at diamond light source

Diamond Light Source is a third generation synchrotron facility dedicated to producingradiation of outstanding brightness. Above a threshold current, the electron bunches aresusceptible to the phenomenon known as the microbunching instability. This instability ischaracterised by the onset of radiation bursts, the wavelength of which is shorter than thebunch length. Near threshold, the bursting occurs quasi-periodically, however at highercurrents, the bursting appears randomly. The high frequencies involved in these emissionsmake detection and analysis challenging. A port specifically for the investigation of mmwave emissions has recently been built at Diamond. Ultra fast Schottky Barrier Diodedetectors have been installed to observe the instability on a turn by turn basis. The onsetand evolution of the bunches have been investigated.