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T: Fachverband Teilchenphysik

T 85: Strahldynamik, Simulation und Polarisation

T 85.4: Talk

Wednesday, March 30, 2011, 17:30–17:45, 30.22: 022

Electron beam for FLASH II — •Matthias Scholz — DESY, Hamburg

FLASH II is a proposed extension of the existing VUV FEL FLASH at DESY, Hamburg. A fast kicker will be installed behind the last superconducting acceleration module, giving the possibility to distribute the beam to two undulator lines, the existing FLASH and FLASH II. A separated tunnel for the new undulator line and a new experimental hall will be build next to the existing FLASH buildings. The extraction chicane design for FLASH II has to fulfill specific conditions to archive sufficient beam properties for the seeding like small emittance- and energy spread growth. Additional, constrains are given by existing FLASH tunnel and surrounding area as well as by the required space for the incoupling of the seed laser. To optimize the extraction lattice, simulations were carried out using ELEGANT computer code including effects like CSR, ISR etc. The best solution was achieved using 4 bending magnets deflecting the beam with 7.0, -0.5, 3.5 and 2.0 degree. For this solution, emittance growth, energy deviation and Twiss functions could be kept in an acceptable range. To mitigate beam quality impairment, the FLASH lattice has to be matched to specified Twiss functions at the extraction point. Thus, the FLASH optic has to be changed upstream and downstream of the extraction point for FLASH II to keep the functionality of the existing FLASH beam line.