DESIGN OF TIME-DEPENDENT ELECTRON-BEAM SPECTRA DIAGNOSTICS FOR THE BEIJING FEL

After passing through the Wiggler and the 180°bend, the electron beam is transported to a time-dependent energy spectrometer. The 180°bend is designed for both achromatic and isochronous to suffice measurements of energy and temporal distributions or time-resolution of macropulses. The time-dependent energy spectra system contains four matching quadrupoles, a two-slit device, a slow-deflector sweep coil, a 90°analyzing magnet with horizontal and vertical focus, a quarts plate at the focal-plane of the magnet, a vidican TV camera with microchannel-plate intensifiers and a picture display system with a on-line micro-computer. Energy-resolution ratio of the spectrometer is large than 1000, while time resolution less than 60 ns.