Wuppertal 2015 – scientific programme

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AKBP: Arbeitskreis Beschleunigerphysik

AKBP 4: FEL, Seeding and Thomson Scattering

AKBP 4.8: Talk

Monday, March 9, 2015, 18:30–18:45, F.10.01 (HS 4)

Demonstration of SASE suppression through a seeded microbunching instability — •Christoph Lechner¹, Sven Ackermann², Armin Azima¹, Jörn Bödewadt², Günter Brenner², Martin Dohlus², Markus Drescher¹, Nagitha Ekanayake², Torsten Golz², Kirsten Hacker³, Katja Honkavaara², Shaukat Khan³, Tim Laarmann², Leslie Lamberto Lazzarino², Torsten Limberg², Theophilos Maltezopoulos¹, Velizar Miltchev¹, Robert Molo³, Tim Plath¹, Juliane Rönsch-Schulenburg¹, Jörg Rossbach¹, Evgeny Schneidmiller², Nikola Stojanovic², and Mikhail Yurkov² — ¹University of Hamburg, Hamburg — ²DESY, Hamburg — ³TU Dortmund University, Dortmund

Collective effects and instabilities due to longitudinal space charge and coherent synchrotron radiation can degrade the quality of the ultra-relativistic, high-brightness electron bunches needed for the operation of free-electron lasers (FELs). In this contribution, we demonstrate the application of a laser-induced microbunching instability to manipulate the electron bunch properties and selectively suppress FEL lasing. A significant decrease of photon pulse energies was observed at the FEL user facility FLASH in coincidence with overlap of 800 nm laser pulses and electron bunches within a modulator located approximately 40 meters upstream of the undulators. We discuss these effects in the framework of longitudinal space charge amplification [E.A. Schneidmiller and M.V. Yurkov, Phys. Rev. ST Accel. Beams 13, 110701 (2010)] and present experimental results.