Investigation of short pulse effects in IR FELs and new simulation results

Abstract The Darmstadt IR FEL is designed to generate wavelengths between 3 and 10 μm and driven by the superconducting electron linear accelerator. The pulsed electron beam has a peak current of 2.7 A leading to a small signal gain of 5%. Currently, investigations of the energy transfer process inside the undulator are performed using the 1D time-dependent simulation code FAST1D-OSC. We present simulation results for the power vs. different desynchronization and tapering parameters as well as a comparison with experimental data from the S-DALINAC IR-FEL. Furthermore, a compact autocorrelation system assuring a background-free measurement of the optical pulse length is described. In a first test experiment at FELIX, the autocorrelator has been tested at wavelengths 5.7 ≤λ≤9.0 μm. The frequency doubling in a 2 mm-long ZnGeP 2 -crystal resulted in a time resolution of 300 fs and a conversion efficiency of 5%.© 2003 Elsevier Science B.V. All rights reserved. PACS: 41.60. Cr; 42.60. Fe; 42.65. Ky; 42.65. Re