Prof. Dr. Thomas Elsässer is a researcher with the Max-Born Institute for Nonlinear Optics and Short Pulse Spectroscopy in the Forschungsverbund Berlin e.V., Max-Born-Str. 2A D 12489, Berlin, Germany, Tel. +49 3063 92-1400, Fax: +49 3063 92-1509, elsasser@mbi-berlin.de, www.mbi-berlin.de.Bernhard Brecht is a design engineer and Dr. Sven Baumgarten is the head engineer of the CFD Group at KSB AG, Johann-Klein-Straße 9 67227, Frankenthal, Germany, +49 6233 86-3702, Fax: +49 6233 86-3456, bernhard.brecht@ksb.com, sven.baumgarten@ksb.com, www.ksb.com.