Experimental Study of the FEL with a Tapered Undulator and Numerical Simulations of Short Pulse Free Electron Lasers.
Technische Universität, Darmstadt
[Ph.D. Thesis], (2003)
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|Item Type:||Ph.D. Thesis|
|Title:||Experimental Study of the FEL with a Tapered Undulator and Numerical Simulations of Short Pulse Free Electron Lasers|
In the present work the influence of tapering with respect of the FEL efficiency has been systematically investigated for the Darmstadt FEL experimentally and theoretically. In this context the experiments performed at the electron accelerator S-DALINAC with an electron beam of 31 MeV at a wavelength of 7 µm were analyzed. The tapering was investigated for ? = - 16.48, - 14.14, - 9.44, - 4.73, 4.74 and 9.5. The experiment shows an efficiency increase of about 15 % due to tapering in the vicinity of ? = - 4.73 and 4.74. The experimental data were compared with theoretical predictions based on an elaborate simulation program. This simulation program has been extended considerably in order to be applicable for the experimental conditions of the FEL at the S-DALINAC. The input parameters of the one dimensional code were adjusted to the experimental conditions e.g. the optical macropulse evolution and were tested for the observables for the untapered undulator with respect to the small signal gain, power desynchronization and line width obtained from measurements performed at the S-DALINAC and FELIX. The predictions of this one dimensional code for the tapered case are in very good agreement with the present experimental data as well as with the results from the TJNAF. It can thus be stated that in the present thesis an effect of tapering with respect to the efficiency of the FEL was found for the first time for oscillator as predicted by the simulations carried out within the frame of the present work.
|Place of Publication:||Darmstadt|
|Uncontrolled Keywords:||FEL, tapering, nonuniform undulator, short pulse FEL|
|Divisions:||05 Department of Physics|
|Date Deposited:||17 Oct 2008 09:21|
|Last Modified:||07 Dec 2012 11:49|
|Referees:||Richter, Prof. Dr. Achim and Seelig, Prof. Dr.- Wolfgang|
|Advisors:||Richter, Prof. Dr. Achim|
|Refereed:||9 December 2002|