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TY - CONF AU - Krämer, J.M. AU - Baurichter, A. AU - Budde, M. AU - Bødker, F. AU - Irman, A. AU - Lehnert, U. AU - Michel, P. AU - Schramm, U. ED - Petit-Jean-Genaz, Christine ED - Arduini, Gianluigi ED - Michel, Peter ED - Schaa, Volker RW TI - Electron Beam Final Focus System for Thomson Scattering at ELBE J2 - Proc. of IPAC2014, Dresden, Germany, June 15-20, 2014 C1 - Dresden, Germany T2 - International Particle Accelerator Conference T3 - 5 LA - english AB - The design of an electron beam Final Focus System (FFS) aiming for high-flux laser-Thomson backscattering x-ray sources at ELBE* is presented. A telescope system consisting of four permanent magnet based quadrupoles was found to have significantly less chromatic aberrations than a quadrupole triplet. This allows sub-ps electron beam focusing to match the laser spot size at the interaction point. Focusing properties like the position of the focal plane and the spot size are retained for electron beam energies between 20 and 30 MeV by adjusting the position of the quadrupoles individually on a motorized stage. Since the electron beam is chirped for bunch compression upstream, the rms energy spread is increased to one or two percent and second order chromatic effects must be taken into account. For an emittance of 13 pi mm mrad, we predict rms spot sizes of about 40 um and divergences of about 15 mrad. We also present the design of the permanent magnet quadrupoles to be used for the FFS. Ferromagnetic poles ensure a high field quality and adjustable shunts allow for fine adjustment of the field strength and compensation of deviations in the permanent magnet material. PB - JACoW CP - Geneva, Switzerland SP - 2995 EP - 2997 KW - quadrupole KW - permanent-magnet KW - electron KW - focusing KW - laser DA - 2014/07 PY - 2014 SN - 978-3-95450-132-8 DO - 10.18429/JACoW-IPAC2014-THPRO055 UR - http://jacow.org/ipac2014/papers/thpro055.pdf ER -