Paper | Title | Page |
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TUPRI042 | Numerical Study of the Microbunching Instability at UVSOR-III: Influence of the Resistive and Inductive Impedances | 1656 |
SUSPSNE061 | use link to see paper's listing under its alternate paper code | |
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At high charge, relativistic electron bunches circulating in storage rings undergo an instability, the so-called microbunching or the CSR (Coherent Synchrotron Radiation) instability. This instability is due to the interaction of the electrons with their own radiation and leads to the formation of microstructures (at millimeter scale) in the longitudinal phase space. Thanks to a new type of detector, based on superconducting thin film YBCO, it is now possible to observe directly these microstructures and follow their temporal evolution*. These experimental observations open a new way to make severe comparisons with theory. Here we present results of the modeling of the dynamics at UVSOR-III using a one dimensional Vlasov-Fokker-Planck equation. We show that to obtain a relatively good agreement between numerical simulations and experiments, we have to take into account several types of impedance such as the shielded CSR impedance but also the resistive and inductive impedances.
* First Direct, Real Time, Recording of the CSR Pulses Emitted During the Microbunching Instability, using Thin Film YBCO Detectors at UVSOR-III, IPAC2014 |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI042 | |
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WEPRO002 | Studies of Ultrashort THz Pulses at DELTA | 1936 |
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Funding: Work supported by the DFG, the BMBF, and the state of NRW. At DELTA, a 1.5-GeV electron storage ring operated as a light source by the Center for Synchrotron Radiation at the TU Dortmund University, coherent ultrashort THz pulses are routinely generated by density-modulated electron bunches. Tracking simulations as well as experimental studies using ultrafast THz detectors and an FT-IR spectrometer aim at understanding the turn-by-turn evolution of the density modulation after an initial laser-electron interaction. Furthermore, intensity-modulated laser pulses are applied to create narrow-band THz radiation. This setup is part of the new short-pulse facility based on coherent harmonic generation. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRO002 | |
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THOBA01 | A New Scheme for Electro-optic Sampling at Record Repetition Rates : Principle and Application to the First (turn-by-turn) Recordings of THz CSR Bursts at SOLEIL | 2794 |
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The microbunching instability is an ubiquitous problem in storage rings at high current density. However, the involved fast time-scales hampered the possibility to make direct real-time recordings of theses structures. When the structures occur at a cm scale, recent works at UVSOR*, revealed that direct recording of the CSR electric field with ultra-high speed electronics (17 ps) provides extremely precious informations on the microbunching dynamics. However, when CSR occurs at THz frequencies (and is thus out of reach of electronics), the problem remained largely open. Here we present a new opto-electronic strategy that enabled to record series of successive electric field pulses shapes with picosecond resolution (including carrier and envelope), every 12 ns, over a total duration of several milliseconds. We also present the first experimental results obtained with this method at Synchrotron SOLEIL, above the microbunching instability threshold, and we present direct tests of Vlasov-Fokker-Planck and macroparticle models. The method can be applied to the detection of ps electric fields in other situations where high repetition rate is also an issue.
* First Direct, Real Time, Recording of the CSR Pulses Emitted During the Microbunching Instability, using Thin Film YBCO Detectors at UVSOR-III, IPAC2014 |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THOBA01 | |
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THPME125 | Electrical Field Sensitive High-Tc YBCO Detector for Real-time Observation of CSR | 3533 |
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Funding: We thank Agilent Technologies & Tektronix for supplying oscilloscopes. The work was supported by BMBF (05K2010), ANR (2010 blanc 042301), MEXT (Quantum Beam Tech. Prog.), IMS (Int. Collab. Prog.). High-Tc thin-film YBa2Cu3O7-x (YBCO) detectors were deployed for the real-time observation of Coherent Synchrotron Radiation (CSR). Due to enhanced fabrication techniques enabling the patterning of sub-μm sized detector areas responsivity values as high as 1V/pJ for pulsed THz excitations have been achieved at the ANKA synchrotron facility at the Karlsruhe Institute of Technology (KIT). Response of the detectors is linear over the whole dynamic range of the IR1 beamline. Combining the picosecond scaled response mechanism of the high-temperature superconductor YBa2Cu3O7-x (YBCO) to THz excitations with broad-band readout a temporal resolution of 15 ps full width at half maximum (FWHM) was reached. Real-time resolution of CSR single shots was observed at ANKA and UVSOR-III, the synchrotron facility of the Institute of Molecular Science in Okazaki, Japan. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME125 | |
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THPRO003 | Progress of the LUNEX5 demonstator Project | 2856 |
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LUNEX5 (free electron Laser Using a New accelerator for the Exploitation of X-ray radiation of 5th generation) aims at investigating the production of short, intense, coherent pulses in the 40-4 nm spectral range [1]. It comprises two types of accelerators connected to a single Free Electron Laser (FEL) for advanced seeding configurations (seeding with High order Harmonic in Gas, echo). A 400 MeV superconducting Linear Accelerator, adapted for studies of advanced FEL schemes, will enable future upgrade towards high repetition rate and multi-user operation by splitting part of the macropulse to different FEL lines. A 0.4 - 1 GeV Laser Wake Field Accelerator (LWFA) [2] will also be qualified by the FEL application. After the Conceptual Design Report, R&D has been launched on different sub components. Following transport theoretical studies of longitudinal and transverse manipulation of a LWFA electron beam enabling to provide theoretical amplification, a test experiment is under preparation. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO003 | |
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