Search Results (2 total)

During the preparatory work for the optical-replica synthesizer experiment in the free-electron laser FLASH at DESY, we were able to superimpose a short, approximately 200 fs long pulse from a frequency-doubled mode-locked erbium laser with titanium-sapphire amplifier and an approximately 20 ps long electron bunch in an undulator. This induces an energy modulation in a longitudinal slice of the electron bunch. A magnetic chicane downstream of the undulator converts the energy modulation into a density modulation within the slice that causes the emission of coherent optical transition radiation from a silver-coated silicon screen. Varying the relative timing between electron and laser, we use a camera to record two-dimensional images of the slices as a function of the longitudinal position within the electron bunch.

The VUV and soft x-ray free electron laser FLASH (former VUV-FEL) is a user facility at DESY (Hamburg). In order to optimize the performance of the facility, an accurate characterization of the electron beam properties is essential. The transverse projected emittance, one of the important parameters characterizing the quality of an electron beam, is measured using a four monitor method with optical transition radiation monitors. A normalized rms emittance below 2 mm mrad for a 1 nC beam has been measured. In this paper we describe the experimental setup, data analysis methods, and present experimental results.