Visualizing Electron Beam Dynamics and Instabilities with Synchrotron Radiation at the APS

The Advanced Photon Source (APS) is a third-generation hard x-ray source serving a large scientific user community. In order to characterize the high-brilliance beams, the APS diagnostics beamlines have been developed into a full photon diagnostics suite. We will describe the design and capabilities of the APS visible-light imaging line, the bend magnet x-ray pinhole camera, and a unique diagnostics undulator beamline. Their primary functions are to support APS user operations by providing information on beam sizes (20-100 micrometers), divergence (3 – 25 microradians), and bunch length (20 – 50 ps). Through the use of examples, we will show how these complementary imaging tools are used to visualize the electron dynamics and investigate beam instabilities. Special emphasis will be put on the use of undulator radiation, which is uniquely suitable for time-resolved imaging of electron beam with high spatial resolution and for measurements of longitudinal beam properties, such as beam energy spread and momentum compaction.