title: Microbunching instability in relativistic electron bunches: direct observations of the microstructures using ultrafast YBCO detectors.
abstract: Relativistic electron bunches circulating in accelerators are subjected to a dynamical instability leading to microstructures at millimeter to centimeter scale. Although this is a well-known fact, direct experimental observations of the structures, or the field that they emit, remained up to now an open problem. Here, we report the direct, shot-by-shot, time-resolved recording of the shapes (including envelope and carrier) of the pulses of coherent synchrotron radiation that are emitted, and that are a "signature" of the electron bunch microstructure. The experiments are performed on the UVSOR-III storage ring, using electrical field sensitive YBa2Cu3O(7-x) thin-film ultrafast detectors. The observed patterns are subjected to permanent drifts, that can be explained from a reasoning in phase space, using macroparticle simulations.
authors.affiliation: Laboratoire de Physique des Lasers, Atomes et Molécules (PhLAM), UMR CNRS 8523, Centre d'Études et de Recherches Lasers et Applications (CERLA), Université Lille 1, F-59655 Villeneuve d'Ascq Cedex, France.
authors.forename: E
authors.initials: E
authors.lastname: Roussel
authors.affiliation: Laboratoire de Physique des Lasers, Atomes et Molécules (PhLAM), UMR CNRS 8523, Centre d'Études et de Recherches Lasers et Applications (CERLA), Université Lille 1, F-59655 Villeneuve d'Ascq Cedex, France.
authors.forename: C
authors.initials: C
authors.lastname: Evain
authors.affiliation: Laboratoire de Physique des Lasers, Atomes et Molécules (PhLAM), UMR CNRS 8523, Centre d'Études et de Recherches Lasers et Applications (CERLA), Université Lille 1, F-59655 Villeneuve d'Ascq Cedex, France.
authors.forename: C
authors.initials: C
authors.lastname: Szwaj
authors.affiliation: Laboratoire de Physique des Lasers, Atomes et Molécules (PhLAM), UMR CNRS 8523, Centre d'Études et de Recherches Lasers et Applications (CERLA), Université Lille 1, F-59655 Villeneuve d'Ascq Cedex, France.
authors.forename: S
authors.initials: S
authors.lastname: Bielawski
authors.affiliation: Institute of Micro- and Nanoelectronic Systems, Karlsruhe Institute of Technology (KIT), 76187 Karlsruhe, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Raasch
authors.affiliation: Institute of Micro- and Nanoelectronic Systems, Karlsruhe Institute of Technology (KIT), 76187 Karlsruhe, Germany.
authors.forename: P
authors.initials: P
authors.lastname: Thoma
authors.affiliation: Institute of Micro- and Nanoelectronic Systems, Karlsruhe Institute of Technology (KIT), 76187 Karlsruhe, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Scheuring
authors.affiliation: Institute of Micro- and Nanoelectronic Systems, Karlsruhe Institute of Technology (KIT), 76187 Karlsruhe, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Hofherr
authors.affiliation: Institute of Micro- and Nanoelectronic Systems, Karlsruhe Institute of Technology (KIT), 76187 Karlsruhe, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Ilin
authors.affiliation: Institute of Micro- and Nanoelectronic Systems, Karlsruhe Institute of Technology (KIT), 76187 Karlsruhe, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Wünsch
authors.affiliation: Institute of Micro- and Nanoelectronic Systems, Karlsruhe Institute of Technology (KIT), 76187 Karlsruhe, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Siegel
authors.affiliation: Graduate School of Engineering, Nagoya University, Nagoya 464-8603, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Hosaka
authors.affiliation: Graduate School of Engineering, Nagoya University, Nagoya 464-8603, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Yamamoto
authors.affiliation: Graduate School of Engineering, Nagoya University, Nagoya 464-8603, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Takashima
authors.affiliation: Institute of Advanced Energy, Kyoto University, Uji 611-0011, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Zen
authors.affiliation: UVSOR Facility, Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki 444-8585, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Konomi
authors.affiliation: UVSOR Facility, Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki 444-8585, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Adachi
authors.affiliation: UVSOR Facility, Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki 444-8585, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Kimura
authors.affiliation: UVSOR Facility, Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki 444-8585, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Katoh