Paper | Title | Page |
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MOA02 | First Lasing of a Free Electron Laser in the Soft X-Ray Spectral Range with Echo Enabled Harmonic Generation | 7 |
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We report on the successful operation of a Free Electron Laser (FEL) in the Echo Enabled Harmonic Generation (EEHG) scheme at the FERMI facility at Sincrotrone Trieste. The experiment required a modification of the FEL-2 undulator line which, in normal operation, uses two stages of high-gain harmonic generation separated by a delay line. In addition to a new seed laser, the dispersion in the delay-line was increased, the second stage modulator changed and a new manipulator installed in the delay-line chicane hosting additional diagnostic components. With this modified setup we have demonstrated the first evidence of strong exponential gain in a free electron laser operated in EEHG mode at wavelengths as short as 5 nm. | ||
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Slides MOA02 [5.133 MB] | |
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-MOA02 | |
About • | paper received ※ 21 August 2019 paper accepted ※ 28 August 2019 issue date ※ 05 November 2019 | |
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TUA03 |
Generation of Sub-Femtosecond X-Ray Pulses at SwissFEL | |
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We report on the first generation of sub-femtosecond hard X-ray FEL pulses at SwissFEL. A few microjoule pulses with a single spike in the frequency domain have been predicted by simulations and then experimentally demonstrated. Ultra-short X-ray pulses are produced by the electron bunch with a specially-tailored current profile and longitudinal phase space. This configuration is achieved by means of an optimized nonlinear compression. Two- and three-stage nonlinear compression schemes are compared in terms of FEL performance and stability. We also discuss different FEL lasing regimes that can be realized depending on the particular configuration of the electron beam and undulator settings. | ||
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Slides TUA03 [1.809 MB] | |
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WEB02 | Wire-Scanners with Sub-Micrometer Resolution: Developments and Measurements | 307 |
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Monitors of the beam transverse profile with ever more demanding spatial resolution and minimal invasivity are required by the FEL community. In order to improve the spatial resolution towards the sub-micrometer limit as well as to decrease the impact on the lasing process, nano-fabricated wire-scanners have been manufactured independently at PSI and FERMI by means of a lithographic technique [1,2]. Experimental tests carried out at SwissFEL at a low emittance demonstrated the capability of such innovative wire-scanner solutions to resolve beam transverse profiles with a size of 400-500 nm without being affected by any resolution limit. Status and outlook of nano-fabricated wire-scanners will be presented.
[1] M. Veronese et al., NIM-A, 891, 32-36, (2018). [2] S. Borrelli et al., Comm. Phys.-Nature, 1, 52 (2018). |
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Slides WEB02 [11.196 MB] | |
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEB02 | |
About • | paper received ※ 24 August 2019 paper accepted ※ 28 August 2019 issue date ※ 05 November 2019 | |
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WEP036 | The PolariX-TDS Project: Bead-Pull Measurements and High-Power Test on the Prototype | 396 |
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A collaboration between DESY, PSI and CERN has been established to develop and build an advanced modular X- band transverse deflection structure (TDS) system with the new feature of providing variable polarization of the deflecting force. The prototype of the novel X-band TDS, the Polarizable X-band (PolariX) TDS, was fabricated at PSI following the high-precision tuning-free production process developed for the C-band Linac of the SwissFEL project. Bead-pull RF measurements were also performed at PSI to verify, in particular, that the polarization of the dipole fields does not have any rotation along the structure. The high-power test was performed at CERN and now the TDS is at DESY and has been installed in FLASHForward, where the first streaking experience with beam will be accomplished. We summarize in this paper the status of the project, the results of the bead-pull measurements and the high power test. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEP036 | |
About • | paper received ※ 21 August 2019 paper accepted ※ 26 August 2019 issue date ※ 05 November 2019 | |
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WEP037 | RF Jitter and Electron Beam Stability in the SwissFEL Linac | 400 |
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The X-ray FEL machine SwissFEL at the Paul Scherrer Institut in Switzerland is commissioned and transiting to user operation smoothly. FEL operation requires stringent requirements for the beam stability at the linac output, such as the electron bunch arrival time, peak current and energy. Among other things, a highly stable RF system is required to guarantee the beam stability. The SwissFEL RF system is designed based on the state-of-the-art technologies that have allowed achieving excellent RF stability. The propagation of RF amplitude and phase jitter to the electron beam are analyzed theoretically and compared with the measurements performed at SwissFEL. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEP037 | |
About • | paper received ※ 20 August 2019 paper accepted ※ 27 August 2019 issue date ※ 05 November 2019 | |
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WED01 | Experience with Short-Period, Small Gap Undulators at the SwissFEL Aramis Beamline | 564 |
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The SwissFEL Aramis beamline provides hard X-ray FEL radiation down to 1 Angström with 5.8 GeV and short period, 15 mm, in-vacuum undulators (U15). To reach the maximum designed K-value of 1.8 the U15s have to be operated with vacuum gaps down to 3.0 mm. The thirteen-undulator modules are 4 m long and each of them is equipped with a pair of permanent magnet quadrupoles at the two ends, aligned magnetically to the undulator axis. Optical systems and dedicated photon diagnostics are used to check the alignment and improve the K-value calibration. In this talk the main steps of the undulator commissioning will be recalled and a systematic comparison between the magnetic results and the electron and photon based measurements will be reported to highlight achievements and open issues. | ||
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Slides WED01 [13.825 MB] | |
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WED01 | |
About • | paper received ※ 28 August 2019 paper accepted ※ 06 November 2019 issue date ※ 05 November 2019 | |
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THB03 |
Emittance Measurements and Minimization at SwissFEL | |
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The transverse emittance of the electron beam is a fundamental parameter that determines the performance of free-electron-lasers (FELs). In this contribution, we present emittance measurements carried out at SwissFEL, the X-ray FEL facility that recently started to operate at PSI in Switzerland, including a description of our measurement methods and optimization procedures. We obtained slice emittance values at the undulator entrance down to ~200 nm for an electron beam with a charge of 200 pC and an r.m.s. duration of ~30 fs. Furthermore, we achieved slice emittances as low as ~100 nm for 10 pC beams with few femtosecond duration. | ||
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Slides THB03 [6.285 MB] | |
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THP085 | Status of Athos, the Soft X-Ray FEL Line of SwissFEL | 753 |
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The Athos line will cover the photon energy range from 250 to 1900 eV and will operate in parallel to the hard X-ray line Aramis of SwissFEL. The paper will describe the current layout of the Athos FEL line starting from the fast kicker magnet followed by the dogleg transfer line, the small linac and the 16 APPLE undulators. From there the photon beam passes through the photonics front end and the beamline optics before reaching the experimental stations AMO and FURKA. The focus of this contribution will be on the two bunch operation commissioning (two bunches in the same RF macropulse), which started in 2018, and the characterization of the major components like the APPLE X undulator UE38, the CHIC chicane and the dechirper. The Athos installation inside the tunnel is alternating with Aramis FEL user operation and the first lasing is planned for winter 2019 / 2020. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP085 | |
About • | paper received ※ 30 July 2019 paper accepted ※ 28 August 2019 issue date ※ 05 November 2019 | |
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THP086 | Operation Modes of the SwissFEL Soft X-Ray Beamline Athos | 757 |
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SwissFEL drives the two FEL beamlines Aramis and Athos, a hard and soft X-ray FEL, respectively. The layout of Athos extends from a simple SASE FEL beamline with the addition of delaying chicanes, external seeding and beam manipulation with wakefield sources (dechirper). It reserves also the space for a possible upgrade to self-seeding. This presentation gives an overview on the detailed layout enabling the unique operation modes of the Athos facility. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP086 | |
About • | paper received ※ 23 August 2019 paper accepted ※ 16 September 2019 issue date ※ 05 November 2019 | |
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