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HK: Hadronen und Kerne
HK 35: Instrumentation IV, Accelerators
HK 35.2: Gruppenbericht
Dienstag, 17. März 1998, 17:30–18:00, A
Latest Developments at the S-DALINAC and its Free-Electron-Laser * — •S. Kostial, M. Brunken, S. Döbert, R. Eichhorn, H. Genz, H.-D. Gräf, T. Hampel, U. Laier, H. Loos, A. Richter, S. Richter, A. Stascheck, B. Schweizer, O. Titze, M. Urban, and T. Wesp — Institut für Kernphysik, Technische Universität Darmstadt, Schloßgartenstr. 9, D-64289 Darmstadt
During 1997 the S-DALINAC provided some 4000 hours of beamtime for a variety of nuclear and radiation physics experiments. Nevertheless the experimental area for high energy radiation physics was moved and upgraded for higher beam currents during a scheduled shut down of three months. This period was also used to install a new large acceptance beam transport system from the accelerator to the experimental areas and to improve the optics of the recirculating beam lines.
In order to optimize the S-DALINAC as a driver for the FEL a detailed study of the beamdynamics in the injector was performed, using the tracking code GPT to include nonlinear effects. First very promising results are presented as well as a calibration method, necessary to convert simulation parameters into real accelerator parameters.
Since its first operation in December 1996 significant progress was made in operating the FEL reliably and first experiments using the laser beam at a wavelength of 7µm were performed. Technical improvements including a laser interferometer based stabilization system for the length of the optical cavity and a newly developed online spectrometer for the laser wavelength allowed operation of the laser covering continuously the range from 6.6 to 7.8µm corresponding to the reflectivity range of the dielectric cavity mirrors. With a single CaF lens the laser beam could be focussed to a diameter of 150µm in the optical laboratory corresponding to an areal power density of some 108W/cm2 and was used for first ablation experiments from different tissues.
* Supported by BMBF under contract number 06 DA 820, DFG under contract number 436 UKR 113-19, and Graduiertenkolleg “Physik und Technik von Beschleunigern”.