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abstract:
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This thesis presents an experiment in which the longitudinal profile of an electron beam was measured by studying the coherrent transition radiation (CTR) emitted when the beam strikes a thin conducting foil. A high gain Self Amplified Spontaneous Emission (SASE) Free Electron laser (FEL) was implemented and the source fo the longitudinal beam profile modulation.
Diagnostics measuring very short periodic electron beam modulation will be necessary for future experiments in which the modulating wavelength will be several microns. Up to this point, there have been reliable tools used for such longitudinal beam profile measurements. However, the limits of resolution in these devices are being approached and new and less expensive methods are needed. Transition radiation from an electron beam striking a metallic surface is an easily emplementable and inexpensive diagnostic and is shown to be a reliable diagnostic for the future.
This thesis presents the theoretical calculation of the expected CTR photon spectrums and compares the analysis with an experiment recently done on an electron beam which has been longitudinally modulated by SASE FEL. The accelerator beamline and its parameters important to the experiment are described. Also, discussed, are the requirements on the system needed for the best CTR emission possible and the importance in choosing a good metallic radiating foil. Results from the data are compared with computer simulation in which these issues are taken into account. Also, the experimental results point out approximations used in traditional transition radiation modeling that will not be valid in future CTR experiemnts and more rigorous theorectical analysis will be needed.
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