| Paper | Title | Page |
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| WEPAB001 | Parallel Operation of SASE1 and SASE3 Undulator Sections of European XFEL | 2554 |
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| In the current paper the numerical simulation results for parallel (decoupled) operation of SASE1 and SASE3 undulator sections of European XFEL are presented. The study was based on the idea of betatron switcher imple-mentation. It was shown that it is possible to avoid energy spread growth in SASE1 and to reach the saturation in SASE3 in desirable range of radiation wavelengths by a trajectory kick before SASE1 and its correction before SASE3. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB001 | |
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| WEPAB002 | Pushing the MAX IV 3 GeV Storage Ring Brightness and Coherence Towards the Limit of its Magnetic Lattice | 2557 |
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The MAX IV 3 GeV storage ring is presently being commissioned and crucial parameters such as machine functions, emittance, and stored current have either already been reached or are approaching their design specifications*. Once the baseline performance has been achieved, a campaign will be launched to further improve the brightness and coherence of this storage ring for typical x-ray users. During recent years, several such improvements have been designed**. Common to these approaches is that they attempt to improve the storage ring performance using existing hardware provided for the baseline design. Such improvements therefore present more short-term upgrades. In this paper, however, we investigate medium-term improvements assuming power supplies can be exchanged in an attempt to push the brightness and coherence of the storage ring to the limit of what can be achieved without exchanging the magnetic lattice itself. We outline optics requirements, the optics optimization process, and summarize achievable parameters.
* WEPAB075 & WEPAB076 at IPAC17 ** MOPHO05 at PAC2013, TUPRI026 at IPAC'4, PRAB 19 060701 (2016) |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB002 | |
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| WEPAB003 | The Danish Synchrotron Radiation Light Source ASTRID2 | 2561 |
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| The ASTRID2 synchrotron light source has now been in user operation for more than 3 years, and most of the initially unresolved minor issues have been dealt with. This paper will report on the solutions, and give an over-view of the current status. The problem of the fast injection bumpers, which overheated at high currents, has been solved. The 3rd harmonic Landau cavity has been installed, and it has resulted in a much better lifetime and a more stable beam. We observe vertically unstable beams above a given threshold beam current. Initially this threshold was quite low, but with time, as the vacuum chambers have been conditioned more and more, the threshold has increased steadily, and is now close to the design current of 200 mA. It is planned to add 3 more power supplies to each of the pole-face windings, which are found in all 12 dipoles. These three supplies will in addition to the original quadrupole correctors give a vertical corrector, a horizontal corrector and a skew quadrupole corrector. Furthermore we are presently producing a new timing system, which will allow us to run single-bunch operation, and a fast orbit feedback system. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB003 | |
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| WEPAB004 | Progress Status for the 10 Year Old SOLEIL Synchrotron Radiation Facility | 2564 |
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| Synchrotron SOLEIL has just turned 10 years since its commissioning. The 2.75 GeV facility is now delivering very stable photon beams to 29 beam lines. A total of 5 operation modes are available in top-up. Maintaining and updating the key performance metric remains a daily work facing both aging of components and tighter operation requirements. Low-alpha operation is attracting more beam lines leading us to an upgrade of the Booster (BOO) radiofrequency (RF) system in order to increase the injection efficiency into the storage ring (SR). The femtoslicing experiment is now in production for a hard X-ray beam line; a dedicated chicane has been installed for a second beam line in the soft X-ray regime. The two long canted beam lines can operate simultaneously at minimum gaps since May 2016 thanks to the introduction of a dedicated photon absorber and a fast angle interlock. R&D work in several areas will be reported. In parallel lattice design are in progress both for short term and long term evolution of the ring performance. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB004 | |
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| WEPAB005 | First MOGA Optimization of the Soleil Lattice | 2568 |
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| The first optimization of the nonlinear beam dynamics of the SOLEIL synchrotron radiation light sources using Multi-Objective Genetic Algorithm is reported. After benchmarking ELEGANT against TRACY3, beam lifetime studies with the operation lattice and fine-tuning of the storage ring model, MOGA-ELEGANT was used to find the best settings of quadrupole and sextupole magnets in order to maximize the dynamic and momentum apertures used as proxies for the Touschek lifetime and the injection efficiency respectively. The solutions obtained after one month of computation in the high level computational cluster of SOLEIL using 200 CPUs are detailed. The improvement of the Touschek lifetime obtained with MOGA is confirmed by the beam-based experiments. The beam lifetime of the SOLEIL storage ring was increased experimentally by 40% as predicted by the simulations. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB005 | |
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| WEPAB006 | Performance Improvements of the BESSY II Storage Ring by Optimizing the Phase Acceptance | 2571 |
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| Linear optics modifications in order to improve injec-tion efficiency and for the installation of two IDs in one straight section demand an optimization of the sextupole correction scheme. Four harmonic sextupole families were sufficient with the earlier 8-fold symmetric lattice. Today there are ten families of harmonic sextupole mag-nets in addition to the three families of chromatic sextu-poles. This paper describes our experimental approach to find better settings for these harmonic sextupoles based on the direct optimization of the injection efficiency with a longitudinal phase offset between storage ring and the injector - in our case a booster synchrotron. As demon-strated in the paper, the resulting improvement of the phase acceptance of the ring leads to increased momen-tum acceptance by suppressing 3rd order non-systematic resonances. This increases not only the injection effi-ciency for long bunches but also the Touschek lifetime, the largest contribution to the overall lifetime of low emittance storage rings. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB006 | |
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| WEPAB007 | Pseudo Single Bunch Qualities Added to Short Pulse Operation of BESSY II | 2574 |
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Funding: Work supported by the German Bundesministerium für Bildung und Forschung, Land Berlin and grants of Helmholtz Association BESSY II features sophisticated filling patterns as well as manipulation and separation techniques of custom bunches to serve both timing and photon hungry experiments at the same time*. Recently, the low alpha operation mode, providing bunch lengths as short as 2 ps, was extended by pseudo single bunch options. A robust technique to excite one bunch with constant displacement and enlargement was implemented for pulse picking by resonant excitation (PPRE)** users. In addition, reliable scraping of an isolated bunch to provide zero current bunch length is opening new timing opportunities. The simultaneous usage of different photon characteristics: high intensity CSR, non-bursting CSR, short duration as well as operation mode specific X-rays impose new challenges. Sensitive tune measurements and feedback mechanisms had to be developed for all three dimensions. Negative alpha is in consideration to overcome the top up efficiency constraints. *R. Müller et.al. BESSY II Supports an Extensive Suite of Timing Experiments, IPAC16 **K. Holldack et.al. Single bunch X-ray pulses on demand from a multi-bunch SR source, Nature Comm.5, 2014 |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB007 | |
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| WEPAB009 | Pilot Experiments and New Developments at the DELTA Short-Pulse Facility | 2578 |
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Funding: BMBF 05K16PEA, BMBF 05K16PEB, Mercur Pr-2014-0047 At the 1.5-GeV synchrotron light source DELTA operated by the TU Dortmund University, ultrashort radiation pulses in the vacuum ultraviolet (VUV) and terahertz (THz) regime are routinely generated by the interaction of electron bunches with femtosecond laser pulses. A laser-induced energy modulation is converted into a density modulation (microbunching) by a magnetic chicane, leading to coherent emission at harmonics of the initial laser wavelength (coherent harmonic generation, CHG). Path length differences of the energy-modulated electrons along the magnetic lattice lead to a dip in the longitudinal charge distribution, which gives rise to the coherent emission of THz radiation. In first pump-probe photoemission experiments, the spatial and temporal overlap of laser pump and CHG probe pulse on the sample was demonstrated. Furthermore, the effect of two temporally separated seed pulses was studied in the VUV and (sub-)THz regime. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB009 | |
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| WEPAB010 | Progress Towards an EEHG-Based Short-Pulse Source at DELTA | 2582 |
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Funding: Work supported by the accelerator initiative (ARD) of the Helmholtz society, BMBF 05K13PE3, BMBF 05K16PEA. The short-pulse source at the 1.5-GeV synchrotron light source DELTA, operated by the TU Dortmund University, enables the generation of sub-ps radiation pulses in the VUV regime based on coherent harmonic generation (CHG). As an upgrade, the employment of echo-enabled harmonic generation (EEHG) is planned which allows to produce shorter wavelengths. Recent developments and measurements regarding the twofold energy modulation required for EEHG are presented. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB010 | |
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| WEPAB011 | High Order Magnetic Field Components and Non-Linear Optics at the ANKA Storage Ring | 2586 |
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| The Karlsruhe Institute of technology operates the 2.5 GeV electron storage ring ANKA as an accelerator test facility and synchrotron radiation source. A superconducting wiggler is installed in a short straight section of the ring where vertical beta-function is large (13 m). The life time of the electron beam was reduced from 15 to 12 hours at a high field level of the wiggler (2.5 T) even though the coherent shift of vertical tune was compensated locally. Computer simulations show the non-linear nature of the effect. The ANKA storage ring operates with strong sextupoles at a positive chromaticity of +2/+6. Even residual octupole components of the wiggler field, set at the tolerance limit of fabrication conditions, could reduce the dynamic aperture for off-momentum particles providing the betatron tune is located in the vicinity of a weak octupole resonance and the chromaticity is high. Also the vertical betatron tune is close to the sextupole resonance Qy=8/3. Large resonance stop-band and proximity of sextupole resonance affect the life time as well. Betatron tunes of ANKA have been shifted away of suspected high-order resonances and beam life time was essentially improved. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB011 | |
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| WEPAB014 | PETRA III Operation | 2589 |
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| At DESY the Synchrotron Light Source PETRA III offers scientists outstanding opportunities for experiments with hard X-rays of exceptionally high brilliance since 2009. This paper describes the challenges of daily operation, including different bunch patterns and their side effects, a procedure to clear spurious bunches, the operational statistics and the main contributions to down time. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB014 | |
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| WEPAB015 | Parameter Optimization for Operation of sFLASH With Echo-Enabled Harmonic Generation | 2592 |
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| The free-electron laser facility FLASH has a dedicated experimental setup for external FEL seeding applications for the XUV and soft x-ray spectral range. Recently the setup is operated as high-gain harmonic generation FEL. Furthermore, it also allows the operation of echo-enabled harmonic generation (EEHG). A versatile laser injection system allows operation with seed wavelength in the infra-red, visible, and ultra-violet. Here, we present the parameter optimization for operating the seeding setup with EEHG. First experimental tests are planned in the first half of 2017. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB015 | |
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| WEPAB016 | Experience in Operating sFLASH With High-Gain Harmonic Generation | 2596 |
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| sFLASH, the experimental setup for external seeding of free-electron lasers (FEL) at FLASH, has been operated in the high-gain harmonic generation (HGHG) mode. A detailed characterization of the laser-induced energy modulation, as well as the temporal characterization of the seeded FEL pulses is possible by using a transverse deflecting structure and an electron spectrometer. FEL saturation was reached for the 7th harmonic of the 266 nm seed laser. In this contribution, we present the latest experimental results. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB016 | |
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| WEPAB017 | Generation of Ultra-Short Electron Bunches and FEL Pulses and Characterization of Their Longitudinal Properties at FLASH2 | 2600 |
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The free-electron laser in Hamburg (FLASH) is a user facility, delivering soft X-ray radiation, consisting of two beam lines, FLASH1 and FLASH2. The injector and the main linac are shared between both beam lines. Starting in 2014, FLASH2 has been commissioned for user operation. Currently, there is no hardware installed for the direct measurement of the electron bunch length nor the photon pulse duration at FLASH2. Exact knowledge of the pulse duration is essential for time-resolved user experiments performed at FLASH. Therefore, we are designing a modified beam line, containing a new type of X-band deflecting cavity* and a dipole, downstream of the FLASH2 undulator, to map the longitudinal phase space onto a beam screen. Anticipating the feasibility of measuring the longitudinal phase space with high resolution, a study on optimizing the free-electron laser (FEL) performance for shortest bunches is ongoing.
*B. Marchetti et al., X-Band TDS project, contribution to these conference proceedings |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB017 | |
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| WEPAB018 | Engineering Collaboration Experience at the European XFEL | 2604 |
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| The construction of the European XFEL involved a huge internationally distributed and inter-disciplinary engineering effort. This paper discusses examples for good engineering practices which have been successfully developed and applied in the construction of the European XFEL. It addresses appropriate combination of de-/central activities in design collaboration and integration; the use of manufacturing bills of materials for coordinating and tracking contributions, as well as for clarifying responsibilities; the right amount of reviews for keeping activities in synch; some specific needs of and measures for in-kind collaboration; and general methods, tools and practices and spirit for efficient communication and collaboration. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB018 | |
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| WEPAB019 | Concept for a Seeded FEL at FLASH2 | 2607 |
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| The free-electron laser (FEL) FLASH is a user facility delivering photon pulses down to 4 nm wavelength. Recently, the second FEL undulator beamline 'FLASH2' was added to the facility. Operating in self-amplified spontaneous emission (SASE) mode, the exponential amplification process is initiated by shot noise of the electron bunch, resulting in photon pulses of limited temporal coherence. In seeded FELs, the FEL process is initiated by coherent seed radiation, improving the longitudinal coherence of the generated photon pulses. The conceptual design of a possible seeding option for the FLASH2 beamline foresees the installation of the hardware needed for high-gain harmonic generation (HGHG) seeding upstream of the already existing undulator system. In this contribution, we present the beamline design and numerical simulations of the seeded FEL. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB019 | |
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| WEPAB020 | Beam Loss Simulations for the Implementation of the Hard X-Ray Self-Seeding System at European XFEL | 2611 |
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| The European XFEL is designed to be operated with a nominal beam energy of 17.5 GeV at a maximum repetition rate of 27000 bunches/second. The high repetition rate together with the high loss sensitivity of the undulators raises serious radiation damage concern, especially for the implementation of the Hard X-ray Self-Seeding (HXRSS) system, where a 100 um thick diamond crystal will be inserted close to the beam in the undulator section. Since the seeding power level highly depends on the delay of the electron beam with respect to the photon beam, it is crucial to define the minimum electron beam offset to the edge of the crystal in the HXRSS chicane. At European XFEL a ~200 m long post-linac collimation section has been designed to protect the undulators. In the HXRSS scheme, however, beam halo hitting the crystal can generate additional radiation. Particle tracking simulations have been performed using GEANT4 and BDSIM for the undulator and the collimation section, respectively. The critical number of electrons allowed to hit the crystal is estimated for a certain operation mode and the efficiency of beam halo collimation is investigated to predict the minimum HXRSS chicane delay. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB020 | |
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| WEPAB021 | Experience with Multi-Beam and Multi-Beamline FEL-Operation | 2615 |
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| DESY's free-electron laser FLASH provides soft X-ray pulses for scientific users at wavelengths down to 4 nm simultaneously in two undulator beamlines. They are driven by a common linear superconducting accelerator with a beam energy of up to 1.25 GeV. The superconducting technology allows the acceleration of electron bunch trains of several hundred bunches with a spacing of 1 microsecond or more and a repetition rate of 10 Hz. A fast kicker-septum system directs one part of the bunch train to FLASH1 and the other part to FLASH2 keeping the full 10 Hz repetition rate for both. The unique setup of FLASH allows independent FEL pulse parameters for both beamlines. In April 2016, simultaneous operation of FLASH1 and FLASH2 for external users started. This paper reports on our operating experience with this type of multi-beam, multi-beamline set-up. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB021 | |
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| WEPAB022 | Background-free Harmonic Production in XFELs via a Reverse Undulator Taper | 2618 |
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| Nonlinear harmonics in X-ray FELs can be parasitically produced as soon as FEL reaches saturation, or can be radiated in dedicated afterburners. In both cases there is a strong background at the fundamental, since it is much stronger than harmonics. One can get around this problem by application of the recently proposed reverse undulator tapering. In this contribution we present numerical simulations of harmonic production in such a configuration as well as recent results from FLASH where the second and the third harmonics were efficiently generated with a low background at the fundamental. We also present the results for a high-contrast operation when the afterburner is tuned to the fundamental. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB022 | |
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| WEPAB023 | First Operation of a Harmonic Lasing Self-Seeded FEL | 2621 |
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| Harmonic lasing is a perspective mode of operation of X-ray FEL user facilities that allows to provide brilliant beams of higher energy photons for user experiments. Another useful application of harmonic lasing is so called Harmonic Lasing Self-Seeded Free Electron Laser (HLSS FEL) that allows to improve spectral brightness of these facilities. In the past, harmonic lasing has been demonstrated in the FEL oscillators in infrared and visible wavelength ranges, but not in high-gain FELs and not at short wavelengths. In this paper we report on the first evidence of the harmonic lasing and the first operation of the HLSS FEL at the soft X-ray FEL user facility FLASH in the wavelength range between 4.5 nm and 15 nm. Spectral brightness was improved in comparison with Self-Amplified Spontaneous emission (SASE) FEL by a factor of six in the exponential gain regime. A better performance of HLSS FEL with respect to SASE FEL in the post-saturation regime with a tapered undulator was observed as well. The first demonstration of harmonic lasing in a high-gain FEL and at a short wavelength paves the way for a variety of applications of this new operation mode in X-ray FELs. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB023 | |
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| WEPAB024 | Commissioning and First Heating with the European XFEL Laser Heater | 2625 |
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Funding: We thank DESY and Swedish research council under Project number DNR-828-2008-1093 for financial support. The Laser Heater of the European XFEL has been installed and commissioning is in progress. We discuss the setup and the results of the first electron beam heating in the injector section. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB024 | |
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| WEPAB025 | Status of the Soft X-Ray Free Electron Laser FLASH | 2628 |
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| The superconducting free-electron laser user facility FLASH at DESY in Hamburg, routinely produces several thousand photon pulses per second. The operational parameters cover a wavelength range from 90 nm down to 4 nm with pulse energies from several uJ up to 1 mJ and with pulse durations of several hundred fs down to a few fs. The FLASH injector and linac drives two undulator beam lines (FLASH1, FLASH2) and therefore FLASH is capable of serving 2 independent experiments with photon pulse (sub-) trains of several 100 bunches at the full train repetition frequency of 10 Hz. We summarize here the highlights of the user operation at FLASH1/2 and the study program (machine development and FEL optimization) of the FLASH facility. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB025 | |
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| WEPAB026 | BRho-Dependent Taylor Transfer Maps for Super-FRS Dipole Magnets | 2631 |
| SUSPSIK049 | use link to see paper's listing under its alternate paper code | |
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| The Super-FRS is an in-flight projectile fragment separator being built at GSI for FAIR. Due to the required high design momentum resolution and large acceptance (Ah= ±40mrad, Av= ±20mrad) the dipole magnets of the Super-FRS have large apertures (38×14cm²). The wide design magnetic rigidity (BRho) range 2-20 Tm requires the variation of the main dipole magnetic field B0 in the range 0.16-1.6 T. Since the upper third of the B0 range is situated in a non-linear saturation region of the magnetization curve B(H) and the spatial distribution of magnetic permeability in the steel yoke is non-uniform, the field distribution in the useful aperture of the magnet is a non-linear and non-uniform function of the excitation current I. One consequence is the shortening of the effective length and the change of the field distribution with increasing I. In this study we analyze these effects for the Super-FRS dipole magnets. We use 3D field distribution from FEM simulations for different I values and a resulting BRho(I). From the fields the Taylor transfer maps for the particles are obtained using DA techniques (COSY-infinity) and the convergence of the resulting transfer maps is discussed. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB026 | |
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| WEPAB027 | Frequency Doubler and Two-color Mode of Operation at Free Electron Laser FLASH2 | 2635 |
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| We report on the results of the first operation of a frequency doubler at free electron laser FLASH2. The scheme uses the feature of the variable gap undulator. Undulator is divided in two parts. The second part of the undulator is tuned to the double frequency of the first part. Amplification process in the first undulator part is stopped at the onset of the nonlinear regime, such that nonlinear higher harmonic bunching in the electron beam density becomes pronouncing, but the radiation level is still small to disturb the electron beam significantly. Modulated electron beam enters the second part of the undulator and generates radiation at the 2nd harmonic. Frequency doubler allows operation in a two-color mode and operation at shorter wavelengths with respect to standard SASE scheme. Tuning of the electron beam trajectory, phase shifters and compression allows to tune intensities of the first and the second harmonic. The shortest wavelength of 3.1 nm (photon energy 400 eV) has been achieved with frequency doubler scheme, which is significantly below the design value for the standard SASE option. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB027 | |
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| WEPAB029 | Optimum Undulator Tapering of SASE FEL: From the Theory to Experiment | 2639 |
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Optimization of the amplification process in FEL amplifier with diffraction effects taken into account results in a specific law of the undulator tapering [*]. It is a smooth function with quadratic behavior in the beginning of the tapering section which transforms to a linear behavior for a long undulator. In practice, undulator consists of a sequence of modules of fixed length separated with intersections. Two modes of undulator tapering can be implemented: step tapering, and smooth tapering. Procedure of the step tapering applies step change of the undulator gap from module to module, and smooth tapering assumes additional linear change of the gap along each module. In this report we simulate the performance of the both experimental options and compare with theoretical limit.
[*] E.A. Schneidmiller and M.V. Yurkov, Optimization of a high efficiency free electron laser amplifier, Phys. Rev. ST Accel. Beams 18 (2015) 030705. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB029 | |
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| WEPAB031 | OCELOT as a Framework for Beam Dynamics Simulations of X-Ray Sources | 2642 |
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| We describe the OCELOT open source project focusing on new beam dynamics simulation capabilities of the whole machine in modern electron-based x-ray sources. Numerical approaches for particle tracking and field calculations are discussed. In developing of the full-dimensional numerical modeling we pursue two important competitive aspects: the simulation has to be fast and has to include accurate estimations of collective effects. The simulation results for the European XFEL [1] are presented. The results have been benchmarked agains other codes and some of such benchmarks are shown. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB031 | |
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| WEPAB032 | A Novel Optical Beam Concept for Producing Coherent Synchrotron Radiation with Large Energy Spread Beams | 2646 |
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| Up to now two FEL concepts are known in conventional accelerators: 1.) In THz lasers an off-crest cavity adds a chirp to the bunch followed by a bunch compressor. Particles with different energies travel on different trajectories to the radiator. 2.) For EUV and X-ray FELs the beam enters an undulator which produces microbunches which then radiate. In this paper it is proposed to copy the THz laser scheme for EUV lasers. The incoming beam is chirped and a dogleg forces afterwards the particles with different energies to move on different parallel trajectories. Considering a detector plane perpendicular to the trajectories the particles with different energies arrive in general at different times. When in this plane for instance a TGU (Transverse Gradient Undulator) is positioned the emitted radiation in the TGU is monochromatic. If in addition chirp and dogleg are selected in such a way that the particles with different energies arrive at the same time at the entrance of the TGU the radiation is monochromatic and coherent similar to the THz laser concept. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB032 | |
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| WEPAB033 | Experimental Optimization and Characterization of Electron Beams for Generating IR/THz SASE FEL Radiation with PITZ | 2650 |
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| The Photo Injector Test facility at DESY, Zeuthen site (PITZ), develops high brightness electron sources for modern linac-based Free Electron Lasers (FELs). The PITZ accelerator can also be considered as a suitable machine for the development of an IR/THz source prototype for pump-probe experiments at the European XFEL. One of the interesting options for the IR/THz generation with PITZ is to generate the radiation by means of a SASE FEL using an uncompressed electron beam with bunch length of a few 10 ps and a peak current of ~200 A. In this paper, results of experimental optimizations and characterizations, including transverse phase space, slice transverse emittance and longitudinal phase space, of electron beams with bunch charges of 4 nC are presented and discussed. The measurements were done with beam momenta of 15 MeV/c and 22 MeV/c. Results of IR/THz SASE FEL calculations by using the GENESIS1.3 code based on the measured beam parameters are also presented and discussed. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB033 | |
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| WEPAB034 | Control of Seeded FEL Pulse Duration Using Laser Heater Pulse Shaping | 2654 |
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| New Free-Electron Laser facilities deliver VUV and X-ray radiation with pulse length in the range of hundreds and tens of fs. A further reduction of the FEL pulse length is desired by those experiments aiming at probing ultrafast phenomena. Unlike SASE FEL, where the pulse duration is mainly driven by the electron bunch duration, in a seeded FEL the pulse duration can be determined by the seed laser properties. The use of techniques able to locally deteriorate the electron beam properties such as emittance or energy spread have been used in SASE FELs to reduce the region of the electron beam that is able to produce FEL radiation and hence reduce the FEL pulse length. The temporal shaping of the laser heater can be used to create an electron beam characterized by a very large energy spread all along the bunch except for a small region. We report measurements of the effect of the laser heater shaping on the electron beam phase-space performed at FERMI. Impact on the final FEL pulse properties are predicted with a series of numerical simulations. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB034 | |
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| WEPAB035 | Elettra Status Present Upgrades and Plans | 2657 |
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| The operational status of the Italian 2.4/2.0 GeV third generation light source Elettra is presented together with an account of some present upgrades and plans for the near future. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB035 | |
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| WEPAB036 | The Diffraction Limited Light Source Elettra 2.0 | 2660 |
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| Elettra 2.0 is the next generation to replace Elettra, the Italian third generation light source. The new machine will have an emittance of 0.25 nm-rad with coherent flux about two orders of magnitude higher than that of the present machine. In the paper the aspects of its feasibility are described and discussed. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB036 | |
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| WEPAB037 | Two-Bunch Operation at the FERMI FEL Facility | 2663 |
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| FERMI is a linac-driven free electron laser (FEL) based upon the High Gain Harmonic Generation (HGHG) scheme. In standard conditions a bunch of 700 pC of charge with sub mm-mrad emittances is accelerated to 1.2-1.5GeV in a normal conducting S-band linac and drives FEL-1 or FEL-2 undula-tor line, which lase respectively in the range 100-20nm or 20-4nm. A number of two-color schemes have been implemented at FERMI for pump/probe experiments, all consisting in making two portions of the same electron bunch lase at two different wavelengths, with a time-separation from 0 to few hundreds of fs. In order to increase the time separation to ns and tens of ns we have explored the acceleration of two inde-pendent electron bunches separated by multiple of the linac main radio-frequency period, i.e. 333ps. Measure-ments and characterization of this two-bunch mode oper-ation are presented, including trajectory control, impact of longitudinal and transverse wakefields on the trailing bunch and manipulation of the longitudinal phase space. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB037 | |
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| WEPAB039 | Development Perspectives at FERMI | 2666 |
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| FERMI is the seeded Free Electron Laser (FEL) user facility at the Elettra laboratory in Trieste, operating in the ultraviolet to soft X-rays spectral range; the radiation produced by the seeded FEL is characterized by a number of desirable properties, such as wavelength stability, low temporal jitter and longitudinal coherence. In this paper, after an overview of the FEL performances, we will present the development plans under consideration for the next 3 to 5 years. These include an upgrade of the linac and of the existing FEL lines, the possibility to perform multipulse experiments in different configurations and an Echo Enabled Harmonic Generation (EEHG) experiment on FEL-2, the FEL line extending to 4 nm (310 eV). | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB039 | |
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| WEPAB040 | Upgrade Plan of Synchrotron Radiation Source at Hiroshima Synchrotron Center, Hiroshima University | 2670 |
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| Hiroshima Synchrotron Radiation Center belonging to Hiroshima University is a user facility of the synchrotron radiation with the wavelength of ultraviolet range for natural science especially including materials and biological sciences. The kely apparatus is an electron storage ring with energy of 700 MeV. This machine is a racetrack shape with large two bending magnets and the injection energy is 150 MeV. It is a very compact size with the circumstance of 30 m, but it has only 2 insertion section and the emittance is much larger than the modern synchrotron radiation sources. Therefore, all of users is eager to upgrade the radiation source with several straight sections and low emittance beam keeping compactness. To meet these requests, we are designing the storage ring based on MAX-III. In this conference, we show the present design of the storage ring and its injector. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB040 | |
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| WEPAB041 | Status Report of Hiroshima Synchrotron Radiation Center Hiroshima University | 2672 |
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| The Hiroshima Synchrotron Radiation Center (HSRC) at Hiroshima University was established in 1996 for the research of solid state physics. The HSRC equips a 700 MeV electron storage ring nicknamed HiSOR. Recently, we are considering upgrade of the instrumentation beamline for the optical monitoring. In this paper, we report the present status of HSRC. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB041 | |
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| WEPAB043 | DQBA Lattice Option for the KEK-LS Project | 2675 |
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| KEK-LS is a fourth generation 3GeV light source and will be constructed in KEK Tsukuba campus. The lattice is 20 cells of ESRF type HMBA (Hybrid Multi Bend Achromat) with short straight section that enables to double the numbers of insertion device beam lines. The circumference is about 570m, and the horizontal natural emittance about 133pmrad. The conceptual design report (CDR) was published in October 2016. Adding two quadrupole magnets to the short straight section of the original lattice in CDR, the lattice design flexibility, emittance and dynamic apertures are improved. In this presentation, we show this new DQBA (Double Quadrupole Bend Achromat) lattice option for KEK-LS project. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB043 | |
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| WEPAB044 | Construction and Commissioning of Direct Beam Transport Line for PF-AR | 2678 |
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| PF-AR was constructed as an accumulator ring for TRISTAN, and in the KEKB era it has been revitalized as a 6.5 GeV synchrotron radiation source. The injection energy was 3 GeV and the beam was accelerated to 6.5 GeV prior to the user run. The original beam transport line (BT) from the LINAC to the PF-AR shared its upstream part with the the BT line of KEKB High Energy Ring (HER). The injection-mode change from PF-AR to HER or vice versa needs about 10 minutes for the magnet cycling procedure of the shared part. In SuperKEKB, the upgrade of KEKB, the lifetime of HER is about 10 minutes. The mode-switch operation of the BT is, therefore, not allowed for maintaining the highest luminosity of the SuperKEKB. In order to avoid this problem, a new 6.5 GeV BT line dedicated to PF-AR has been constructed. This also enables the top-up injection for the user run. The commissioning of the new BT line has been completed in this March, and now the first user run has been operated successfully. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB044 | |
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| WEPAB045 | Development of Dedicated Linac and Booster for KEK PF | 2681 |
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| KEK Photon Factory (PF) is a major light source facility in Japan. The injector of PF is KEK LINAC and it is shared with other three rings; PF-AR, SuperKEKB HER (High Energy Ring) and LER (Low Energy Ring). Due to the large electricity consumption, all accelerators in KEK are shut down during every summer for about 3 months. In 2017, because of the LINAC upgrade for SuperKEKB Phase 2 operation, the summer shutdown will be extended to about 5 months. On the other hand, the PF users always strongly wish the shorter shutdown and longer operation. Especially the structural biology users require the ability for the measurement within about 2 weeks after the irregular sample manufacture throughout the year. In order to satisfy these requests, the independent injector system is required for the realization of such longer operation. The examined system consists of an about 100 MeV small linac and a booster ring in the present PF ring tunnel. We show the results of the feasibility study for the independent injector system for the PF ring. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB045 | |
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| WEPAB046 | New HMBA Lattice for PF-AR | 2684 |
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| Photon Factory Advanced Ring (PF-AR) has been operated for users about 30 years from 1987. The lattice and optics are not almost changed from the original one as the TRISTAN booster ring constructed in 1984. The lattice employs FODO structure and the horizontal emittance for the 6.5 GeV user run is about 300 nmrad. In order to improve the performance of PF-AR dramatically, the full replacement of the accelerator to the ESRF type HMBA (Hybrid multi bend achromat) lattice is examined. In order to geometrically fit the new lattice to the present PF-AR tunnel, the new ring consists of 12 cells with four long straight sections. The emittance is improved to about 500 pmrad at 3 GeV. With the present user experimental hall at the north half of the ring, at least eight undulator beam lines can be constructed. The simulated dynamic aperture is about 1.5 cm at the long straight section with reasonable magnetic errors and COD correction. The Touschek lifetime is about 6 hours. The beam injection with conventional injection system causes no problem and the beam lifetime is long enough. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB046 | |
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| WEPAB047 | Concept of a New Generation Synchrotron Radiation Facility KEK Light Source | 2687 |
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| KEK has proposed a new SR facility: KEK Light Source (KEK-LS) towards the completion of the first half of the 2020s. The energy and the natural horizontal emittance are 3 GeV and 0.13 nm rad, respectively. To mitigate the intra-beam scattering effect, we are planning to install third harmonic RF cavities. The extremely low emittance ring has been designed based on the Hybrid Multi-Bend Achromatic (HMBA) lattice, which was originally developed at the ESRF upgrade project. We have modified it to insert a short straight section at the center of the unit cell. The number of unit cells is 20, and the circumference is about 570 m. Except for an RF section and an injection section, the ring can accommodate 18 undulators in the long straight sections of 5.6 m, and the additional 20 short straight section of 1.2 m will be used for short-period narrow-gap undulators. If we assume an undulator of the magnetic period 20 mm, total length 5.0 m, and the smallest gap 4 mm, the SR brightness approaches 1022 Photons/mrad2/mm2/s/0.1%B.W. at the X-ray range. It has a high coherent fraction of about 20% at the diffraction limit wavelength 0.32 keV. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB047 | |
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| WEPAB048 | Present Status of Accelerators in Aichi Synchrotron Radiation Center | 2691 |
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| Aichi Synchrotron Radiation Center is a synchrotron radiation facility in operation since 2013. The electron energy of the storage ring is 1.2 GeV and the circumference is 72 m. In spite of the compact size of the storage ring, synchrotron radiation up to hard X-ray region (~20 keV) is available from the 5 T super conducting bending magnets. Presently (Dec. 2016), 8 beamlines (5 hard X-ray and 3 soft X-ray) are in operation and 2 new hard X-ray beamlines are under commissioning. This contribution reports on the present status as well as machine studies to improve the performance of the accelerators. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB048 | |
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| WEPAB050 | Commissioning of SESAME Storage Ring | 2694 |
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| SESAME light source uses a 2.5GeV storage ring, designed to produce synchrotron light in the hard X-ray region. The 133.2 m circumference ring composed of 16 Double Bend Achromat cells with 16 dispersive straight sections, offers a maximum capacity of 25 beamlines. The storage ring is filled with electrons using an 800MeV injector of 1 Hz repetition rate. This article reports on the main results and first experience of storage ring commissioning and operation. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB050 | |
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| WEPAB052 | Progress of the Lattice Design and Physics Studies on the High Energy Photon Source | 2697 |
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Funding: Work supported by NSFC (11475202, 11405187, 11205171) The High Energy Photon Source (HEPS) is a 6-GeV, kilometer-scale, ultralow-emittance storage ring light source to be built in Beijing, China. In this paper we will discuss the progress of the lattice design and related physics studies on HEPS, covering issues of storage ring design, booster design, injection design, collective effects, error study, insertion device effects, longitudinal dynamics, etc. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB052 | |
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| WEPAB053 | Candidate Lattice Design of the HEPS Booster Consisting of Combined-Function Dipoles | 2700 |
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Funding: Work supported by NSFC (11475202, 11405187) The High Energy Photon Source (HEPS) is a 6-GeV, ultralow-emittance, kilometer-scale storage ring light source to be built in China. It is planned to use a 300 MeV linac and a full energy booster as the injector. In this paper we present one of the candidate lattice designs for the HEPS booster, where most of the dipoles are combined with quadrupole and sextupole gradients. Global optimization of the lattice has been done, where the dependencies of the lattice performance on various parameters, including the minimum pole face field, damping partition number, number of dipoles, etc. are discussed. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB053 | |
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| WEPAB054 | Candidate HEPS Lattice Design With Emittances Approaching the Diffraction Limit of Hard X-Rays | 2703 |
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Funding: Work supported by NSFC (11475202, 11405187) The High Energy Photon Source is a 6-GeV, kilometre-scale storage ring light source to be built in Beijing. A lattice of the storage ring was proposed, consisting of 48 hybrid 7BAs, and having a natural emittance of 60 pm and a circumference of ~1.3 km. In this paper, we discuss the possibility of further reducing the emittance to approach the diffraction limit of hard X-ray with 'typical' wavelength of 1 Å. We introduce the considerations on the choice of lattice structure and circumference, and concrete lattice designs. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB054 | |
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| WEPAB055 | Characterizing the Nonlinear Performance of a DLSR With the Effective Acceptance of the Bare Lattice | 2706 |
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Funding: Work supported by NSFC (11475202, 11405187, 11605212) In a diffraction-limited storage ring (DLSR) light source, associated with the strong focusing and sextu-poles, the detuning terms are large and integer and half integer resonances can be reached at small momentum deviation and transverse amplitudes. We propose to use the effective ring acceptances of the bare lattice to characterize the nonlinear performance of the actual ring, by considering the limiting effects of integer and half integer resonances on beam dynamics. Such a concept will be very useful in lattice design of a DLSR light source. In this paper, we will discuss the reasoning, verification, and application range of this definition. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB055 | |
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| WEPAB058 | Commissioning Status of the Dalian Cohernet Light Source | 2709 |
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| The Dalian Coherent Light Source (DCLS) is a seeded FEL user facility working at 50-150 nm, now under commissioning in Dalian, China. The facility consists of a 300 MeV normal-conducting S-band linear accelerator (LINAC) and two undulator beamlines. The first beam-line (FEL-1) will provide picosecond FEL radiation with the pulse energy up to several hundreds micro-joule, the second beam-line (FEL-2) will be a femtosecond and polarization FEL. The LINAC and FEL-1 beam-line construction was complete by the summer of 2016, the installation of FEL-2 is in preparation. High power RF conditioning of the LINAC started in August 2016 and the beam commissioning initiated 3 months later. This article describes the commissioning status of DCLS, reports on the goals achieved so far. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB058 | |
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| WEPAB060 | Design Study for the First Version of the HALS Lattice | 2713 |
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| The Hefei Advanced Light Source (HALS) was proposed as a future soft X-ray diffraction-limited storage ring at NSRL. Recently the first version lattice of the HALS storage ring has been studied using a new lattice design concept that we proposed for diffraction-limited storage rings. In this new concept, the beta functions of each cell are made to be locally symmetric. In this paper, an 8BA lattice and a 6BA lattice are designed for the HALS with the first and the second kind of the new concept, respectively. In their nonlinear optimization, good dynamic aperture and momentum aperture can be easily obtained. Especially the dynamic momentum aperture can be larger than 7% or even 10%, which enables long beam lifetime and implementation of longitudinal injection scheme. The studied 6BA lattice is at present considered as the nominal HALS lattice of the first version. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB060 | |
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| WEPAB063 | Considerations on Developing a Dedicated Terahertz Light Source Based on the HLS-II Storage Ring | 2716 |
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| There is an increasing interest in generating terahertz radiation for different kinds of researches. A high-power terahertz light source can be realized through coherent synchrotron radiation from a storage ring. The radiation power of coherent synchrotron radiation is proportional to square of the number of electrons in a bunch. To generate coherent synchrotron radiation, the electron bunch length should be shorter than its radiation wavelength. This paper presents our preliminary study on developing a terahertz light source based on Hefei Light Source. We will introduce the status of Hefei Light Source (HLS) and discusses the approach to change it to a dedicated Terahertz light source using coherent synchrotron radiation. Several schemes are proposed to shorten the electron bunch length in the storage ring, including using a low alpha lattice, adopting a magnetic chicane and upgrading the RF system with much higher frequency. The related beam instabilities are also analyzed to predict the beam current threshold. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB063 | |
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| WEPAB064 | Upgrade Project on Top-Off Operation for Hefei Light Source | 2719 |
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| Hefei Light Source has successfully finished a major upgrade project and has been officially opened to users since January 2015. The upgrade project mainly includes increasing the linac injector energy from 200 MeV to 800 MeV which is the same as the ring energy, changing the ring lattice structure from TBA to DBA in order to provide more straight sections for insertion devices while keeping the circumference unchanged, and lowering the beam emittance to obtain higher photon brightness. Before the upgrade project, decay mode is the only choice for the operation of Hefei Light Source. This is because the injected beam from the linac injector needs to be ramped up to 800 MeV after injection. At prensent we have the conditions to operate Hefei Light Source with top-off mode since the linac can perform full-energy and bunch-by-bunch injection. The main challenge for the top-off operation is to control the radiation dose for personal and equipment safety, and to maintain high stability and reliability of the injector. In this paper, we report our work on the top-off operation project for Hefei Light Source. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB064 | |
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| WEPAB065 | Proposal for the Generation of Terawatt, Attosecond X-Ray Pulses in Free Electron Lasers | 2723 |
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| A feasible novel method is proposed to generate attosecond terawatt X-ray radiation pulse in free electron lasers, which could find its application on multiple science fields. In our scheme, a chirped laser is employed to generate a chirped periodic current enhancement and a series of spatiotemporal shifters are applied between the undulator sections to generate ultra-short radiation pulse. Three-dimensional start-to-end simulations are carried out and the calculation results show that a 0.15nm X-ray pulse with the peak power of about 1TW and the pulse length of 0.1fs could be achieved in our scheme. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB065 | |
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| WEPAB066 | POP Experiment for the HB-HGHG Scheme at SXFEL | 2727 |
| SUSPSIK010 | use link to see paper's listing under its alternate paper code | |
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| Abstract High brightness, fully coherent and ultra-short free electron lasers (FEL) operating in the soft x-ray region are opening up new frontiers in many scientific fields. In this paper, we perform the design studies for the proof-of-principle experiment of the recently proposed HB-HGHG scheme at SXFEL test facility with a two-stage setup. The first stage of SXFEL is used for the generation of the coherent signal at 30th harmonic of the seed through the coherent harmonic generation process. Then this coherent signal is shifted ahead by the 'fresh bunch' chicane of SXFEL and initiates the strong coherent radiation in the radiator of the second stage of SXFEL. The output properties have been compared with the conventional EEHG and the two-stage cascaded HGHG with the same harmonic up-conversion number. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB066 | |
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| WEPAB067 | Electron Beam Lifetime in SOLARIS Storage Ring | 2731 |
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| Solaris storage ring is a recently constructed and commissioned machine. At the beginning of storage ring operation the lifetime was very short mostly dominated by the ion trapping and residual gas scattering. After a 390 A·h of beam cleaning the measured total lifetime has reached 20 h for 100mA of a stored current. Since the main contribution to the total lifetime in the storage ring comes from single Coulomb and Touschek scattering the dependence of the residual gas pressure and the vertical aperture of storage ring is investigated. Moreover to improve the Touschek lifetime the 3rd harmonic cavities were installed. Recently the cavities were tuned close to the resonance and the total lifetime increased significantly. This presentation will report on the lifetime measurements and calculations carried out for Solaris 1.5 GeV storage ring at different vacuum and RF conditions. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB067 | |
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| WEPAB068 | Residual Gas in the Vacuum System of the Solaris 1.5GeV Electron Storage Ring | 2734 |
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| Solaris is a third generation light source constructed at the Jagiellonian University in Kraków, Poland. The machine was designed by the MAX IV Laboratory team. The replica of the 1.5 GeV storage ring with 96 m circumference of a vacuum system was successfully built and now the synchrotron facility is after the 3rd phase of commissioning. Recent installation of the Residual Gas Analyzer (RGA) in the storage ring allows now for evaluation of the residual gas composition. Within this paper the result of residual gas analysis in the vacuum system of storage ring during different states of the machine will be presented. Result of vacuum performance regarding beam cleaning and beam lifetime will be presented. Moreover, the NEG strips performance will be evaluated and reported. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB068 | |
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| WEPAB069 | Possible Suppression of Head-Tail Instability by a Feedback Kicker for a Light Source Without Any Sextupole | 2738 |
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| As storage ring based light sources pursue as low emittance as possible down to the diffraction limited number by adopting as many bending magnets and quadrupoles in a cell, the number of sextupole magnets required to correct chromaticity and secure a sufficiently big dynamic aperture grows substantially. As a result, the circumference of a multi-bend achromatic lattice storage ring is typically very long. This paper discusses over a possible scheme to run a storage ring without sextupole magnets at all and suppress the head-tail instability by using a transverse feedback kicker. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB069 | |
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| WEPAB070 | Study of ESASE Scheme with Microbunching Instability for Generating Attosecond-Terawatt X-Ray Pulse in XFELs | 2741 |
| SUSPSIK011 | use link to see paper's listing under its alternate paper code | |
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| Recent studies show that the attosecond-terawatt X-ray pulse in XFELs can be generated by using ESASE (enhanced self-amplified spontaneous emission) scheme to obtain a sub-femtosecond spike in the electron peak current. However, ESASE scheme is not working properly when the microbunching instability is taken into account. The instability can be suppressed when the laser heater system which increases the uncorrelated energy spread of the electron beam is used in the injector. The effect of the microbunching instability on the performance of ESASE scheme will be discussed. In addition, the optimized results with the laser heater system for generating attosecond-terawatt X-ray pulse in XFELs is also presented. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB070 | |
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| WEPAB071 | Single Bunch Bucket Selection Injection Modes in the ALBA Storage Ring | 2744 |
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| The ALBA Synchrotron has been operating routinely in top-up mode since 2014, performing reinjections of multi-bunches every 20 minutes. Recently, the control of the timing has been upgraded to allow single bunches to be injected into any storage ring bucket and therefore to top up the stored current also in single bunch injector mode. In addition, by means of a specific algorithm, a new injection mode called Single Bunch Bucket Selection (SBBS) has been developed to provide any kind of filling pattern in the ALBA storage ring. This mode controls independently the amount of current injected into each bucket, and injects first into those buckets with lowest charge. When used in top-up mode, SBBS keeps the charge distribution of the filling pattern with a uniformity below 10%. The improved flexibility and stability of the filling pattern increases the scope of research for the ALBA experiments and for machine studies development. The implementation of the new injection modes and their performance are presented. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB071 | |
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| WEPAB072 | Apple II Undulator and Front End Design for the New LOREA Beamline at ALBA | 2747 |
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| ALBA synchrotron has started the construction of a new beamline LOREA, for Low-Energy Ultra-High-Resolution Angular Photoemission for Complex Materials. It will operate in the range of 10 to 1500 eV and will use polarized light. In order to produce the light to be used in this beamline, several options have been studied, and finally an Apple II design has been chosen. The device can operate as an undulator at low energies and as a wiggler at high energies, reaching a wide energy range. The high demanding characteristics of the beamline in terms of energies lead to a device providing high power and wide beam in some working modes. This situation has been a challenge for the Front End design, especially for the vertically polarized mode, with some changes with respect to standard ALBA front ends. In this paper we present the magnetic design and expected performances of the device, that currently is being built by KYMA, as well as the Front End design, that currently is being built by RMP and TVP. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB072 | |
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| WEPAB073 | First Measurements of Pulse Picking by Resonant Excitation (PPRE) at the MAX IV 3 GeV Storage Ring | 2750 |
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| At synchrotron light storage rings there is demand for serving high-brilliance users requesting multibunch operation while simultaneously serving timing users who require single-bunch operation. One method to accomplish this is PPRE developed and currently in user operation at BESSY-II. In the method, the transverse emittance of one of the bunches in the bunch train is increased by an incoherent betatron excitation. Part of the light from this bunch can then be separated from the multibunch light by an aperture in the beamline, resulting in single-bunch light for the experiment. Methods such as this expand the scope of storage rings without requiring special fill patterns. This is of growing interest due to the upgrade trend towards diffraction-limited storage rings where it becomes more challenging to operate with inhomogeneous fill patterns. Measurements of PPRE were performed at the MAX IV 3 GeV storage ring utilizing the bunch-by-bunch feedback system both for excitation and as a diagnostic. Furthermore, measurements involving direct beam imaging at the diagnostics beamline allowed quantifying the effect of this excitation on the horizontal and vertical emittance. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB073 | |
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| WEPAB074 | On the Coherence Properties of FEL | 2753 |
| SUSPSIK012 | use link to see paper's listing under its alternate paper code | |
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Free Electron Lasers (FEL) are one of the most brilliant light sources in the world and their unique properties are driving worldwide research in understanding and improving them. Numerous papers have already been published describing the output of the FEL in terms of coherence and bandwidth. In this contribution, however, we focus on how the coherence evolves along the FEL undulator and on what factors influence it the most. Using Genesis−1.3* we have been able to follow and record the light field as it is being produced in the undulator. Our analysis method takes advantage of the extensively studied double pinhole experiment and uses the principles behind it to create a tool for extracting coherence information from the radiation field. We will present the scope, limitations and advantages of these virtual experiments as well as an application on an example FEL, to showcase what kind of information can be extracted using this method.
* Numerical simulation code used for particle and field distribution tracking along the undulator developed by Sven Reiche |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB074 | |
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| WEPAB075 | First Optics and Beam Dynamics Studies on the MAX IV 3 GeV Storage Ring | 2756 |
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| We present results from beam commissioning of the MAX IV 3 GeV storage ring as well as a summary of the beam dynamics studies that have so for been carried out. We report on injection and accumulation using a single dipole kicker, top-up injection, slow orbit feedback, restoring the linear optics to design, effects of in-vacuum undulators with closed gaps, and adjusting nonlinear optics to achieve design chromaticity correction as well as dynamic aperture sufficient for high injection efficiency and good Touschek lifetime. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB075 | |
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| WEPAB077 | The Soft X-Ray Laser Project at MAX IV | 2760 |
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A soft x-ray laser beamline utilising FEL technology is being designed for the Short Pulse Facility (SPF) at the MAX IV Laboratory. A conceptual design study has been started following on the scientific case already prepared in collaboration between several Swedish Universities and driven by a strong (Swedish) user demand [*]. The baseline goal of the SXL beamline is to generate intense and short pulses in the range 1-5 nm (1-0.2 keV). The system is building on the MAX IV linac system, already today providing 3 GeV and pulses compressed to 100 fs for other applications within the SPF. As a special feature we foresee a variety of pump-probe capabilities. We here describe design issues and solutions for the accelerator and FEL system.
* http://frielektronlaser.se/onewebmedia/SXLsciencecase161102.pdf |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB077 | |
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| WEPAB083 | Development of Linac-Based MIR/THz FEL Facility and Photocathode RF-gun in Thailand | 2763 |
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| A linac-based MIR/THz free-electron laser facility is under the development at the Plasma and Beam Physics Research Facility, Chiang Mai University. The ultimate goal of the project is to generate the infrared radiation covering the wavelengths from 13 to 125 μm. The main applications of the radiation involved MIR/THz imaging and spectroscopy. The future FEL facility will consists of an injector system, an experimental station for coherent transition radiation, two magnetic bunch compressors and two undulator magnets equipped with optical cavities for MIR and THz beamlines. An expected electron beam energy is between 10 to 20 MeV with an energy spread of about or less than 1 %. Two undulator magnets with maximum undulator parameters of 1 and 0.95 will be used for generation of the THz-FEL and MIR-FEL, respectively. In this paper, we present the status of the design and construction of this future FEL facility. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB083 | |
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| WEPAB084 | Development of Injector System for MIR/THz Free-Electron Laser Facility in Thailand | 2767 |
| SUSPSIK013 | use link to see paper's listing under its alternate paper code | |
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| Development of a linac-based MIR/THz FEL light source is ongoing at the Plasma and Beam Physics Research Facility, Chiang Mai University. The future facility will consist of an S-band thermionic cathode RF electron gun, a pre-magnetic bunch compressor in a form of alpha magnet, an S-band travelling-wave linac structure, a 180-degree achromat system and two undulator magnets equipped with optical cavities. This research focuses on start-to-end beam dynamics simulations of the injector system. The aim of the study is to produce high quality electron beam at the entrance of the THz undulator magnet. The simulation was conducted by using programs PARMELA and ELEGANT. The program PARMELA was utilized to study the electron beam dynamics inside the RF-gun. Then, the program ELEGANT was used to optimize the injector system parameters. Optimization of physical specifications for the achromat system was performed to obtain short electron bunches with small energy spread at the undulator entrance. In this paper, results of beam dynamics simulations with suitable condition for the THz-FEL beamline are presented and discussed. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB084 | |
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| WEPAB085 | Siam Photon Source: Present Machine Status and Future Upgrades | 2770 |
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| Siam Photon Source, the Thailand synchrotron light source, has received several upgrades in recent years. Most important of which are the improvement of the positional stability of the stored electron beam, and the installation of 2 IDs, i.e. a 2.2 T hybrid multipole wiggler and a 6.5 T superconducting wavelength shifter, to extend the available SR spectrum into hard x-ray region. The beam stability improvement was achieved through several activities, including improving the BPM system, upgrading the existing corrector power supplies, and implementing global orbit feedback. The two new IDs provide higher-intensity and higher-energy (up to 25 keV) synchrotron light, which will be utilized for MX, high-energy SAXS, WAXS, XAS, and microtomography. Ongoing machine upgrades include increasing the energy of the booster and transport line to 1.2 GeV for full-energy injection and eventual top-up operation. Utilization of the electron beam is also being explored. A beam test facility, which extracts electron beam in the booster for characterizing high-energy particle sensors, as well as calibrating other beam diagnostic instruments, has been constructed and is now in operation. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB085 | |
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| WEPAB086 | Design and Optimisation of SPS-II Storage Ring | 2773 |
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| Siam Photon Source (SPS) in Thailand has been operating and providing synchrotron radiation to users for more than a decade, leading to growing user community in South East Asia region. This gives rise to the possibility of constructing a new 3 GeV light source which could provide synchrotron light with higher photon energy and higher brilliance than the existing 1.2 GeV machine. Hybrid multi-bend achromat (HMBA) lattice design providing small natural beam emittance is a promising choice. In this paper, the Double-Triple Bend Achromat (DTBA) design with extra straight section scaled from Diamond Light Source upgrade lattice [ref.] is presented. Lattice optimisation with simplified magnet specifications still allows natural emittance of about 900 pm'rad for a 321.3 m circumference ring with sufficient dynamic aperture. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB086 | |
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| WEPAB087 | TARLA: The First Facility of Turkish Accelerator Center (TAC) | 2776 |
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Funding: Work supported by Ministry of Development of Turkey Turkish Accelerator and Radiation Laboratory in Ankara (TARLA) is proposed as first accelerator based infrastructure in Turkey as a first step Turkish Accelerator Center (TAC). The facility under construction at Institute of Accelerator Technologies of Ankara University since 2012. Based superconducting technology, TARLA accelerator will offer a multi-experiment facility providing various accelerator-based radiation sources for the users coming from different fields like physics, chemistry, biology, material sciences, medicine and nanotechnology. Two of the planed free-electron laser (FEL) beamlines of TARLA will provide Continuous Wave (CW) tunable radiation of high brightness in the mid- and far-infrared regime. In addition a Bremmstrahlung radiation station is proposed within current scope of TARLA. In this paper current status of facility is presented. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB087 | |
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| WEPAB088 | Dark Current Studies in the CLARA Front-End Injector | 2779 |
| SUSPSIK014 | use link to see paper's listing under its alternate paper code | |
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| At STFC Daresbury a new facility CLARA (Compact Linear Accelerator for Research and Applications) is being designed and constructed. The principal aim of CLARA is advanced Free Electron Laser research. Halo and dark current in CLARA is a concern for damage to the undulator, and other applications of the machine. Recently the front end (gun, diagnostics, first linac) of CLARA has been installed including some collimation to mitigate halo effects. Beam halo may arise from gun field emission or due to beam dynamics in the early stages of acceleration, which may achieve the same energy as the core beam and thus may be transported to the undulator. The code CST is used to study the gun field emission. The code ASTRA is used to study the transport of field emission through the front end, including the effectiveness of collimators. Machine measurements of dark current are compared against these simulations. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB088 | |
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| WEPAB089 | Design Study for the Generation of Few-Cycle FEL Pulses Using Mode-Locked Afterburner Scheme at Clara | 2783 |
| SUSPSIK015 | use link to see paper's listing under its alternate paper code | |
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| Ultrashort pulse operation in FELs is a highly desirable capability for imaging matter on ultrafast timescales. This paper presents a design study for a proof-Âof-Âprinciple demonstration of the mode-locked afterburner (ML-AB) scheme on the FEL test facility CLARA. A start-to-end simulation has been constructed using the time-Âdependent three-Âdimensional FEL code GENESIS 1.3 to evaluate the performance of the scheme. The ability to produce pulses of several femtoseconds in duration with peak powers of the order of 100 MW at 100 nm wavelength is predicted. Such pulses have duration of 2 fs (6 optical cycles), a factor of ~5 shorter than the FEL cooperation length. Potential routes for further optimisation and alternative operating modes are explored. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB089 | |
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| WEPAB090 | Developments in the CLARA FEL Test Facility Accelerator Design and Simulations | 2787 |
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| We present recent developments in the accelerator design of CLARA (Compact Linear Accelerator for Research and Applications), the proposed UK FEL test facility at Daresbury Laboratory. The requirement to co-propagate the beam with laser seeds of very different wavelengths has led to a redesign of the section preceding the undulators, with a dogleg being replaced by a chicane. Additional refinements of the facility design include the inter-undulator sections. With this finalised design we show start to FEL simulations for all beam modes envisaged. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB090 | |
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| WEPAB091 | Progress on Transparent Realignment of the Diamond Storage Ring | 2790 |
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| The mechanical alignment of Diamond Storage Ring is achieved by means of a 5-axis motion system under remote control via the EPICS toolkit from the Diamond Control Room. We have completed the first phase of the realignment program meant to improve the mechanical alignment of the machine by carefully moving the magnet girders with a virtually zero impact on the associated beamlines, hence the name Transparent Realignment (TR). During this phase we have equipped and realigned 3 out of 24 cells, involving two beamlines. We have also tested and perfected the technique to execute a move with live beam and total remote control of the realignment process. The program has entered a second phase entailing the commissioning of 6 more cells. Details of tests on the machine are reported. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB091 | |
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| WEPAB093 | Mechanical Engineering of the Diamond DDBA Upgrade | 2794 |
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| The Diamond storage ring has been upgraded to replace one cell of Double Bend Achromat (DBA) with a Double Double Bend Achromat (DDBA). This upgrade has enabled the construction of a new straight to install a much brighter insertion device X-ray source for a new beamline rather than use a weaker bending magnet source. The engineering challenges and experience from this project are described, especially those aspects relevant to building a future low emittance storage ring at Diamond. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB093 | |
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| WEPAB094 | Diamond: Ten Years of Operation | 2797 |
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| In January 2017 Diamond Light Source reached ten years of operation, providing beam to beam lines and users. At the start of operations there was an initial suite of 7 beam lines, phase 1. We are now in the later part of a phase 3 beam line upgrade bringing the total number of beam lines up to 29+ which is close to maximum capacity. The 3GeV storage ring has had a number of modifications and improvements across the last 10 years culminating in the recent (Autumn 2016) addition of a major local lattice modification, DDBA , reported elsewhere at this conference. This review paper will look at machine improvements operationally and machine developments that improved overall performance. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB094 | |
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| WEPAB095 | Electron Beam Commissioning of the DDBA Modification to the Diamond Storage Ring | 2800 |
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The Diamond storage ring has been modified by replacing one of the existing double bend achromat (DBA) cells with a double-DBA (DDBA) cell*. This change represents the largest modification to the storage ring since it was first commissioned in 2006, and was installed and fully commissioned during a single 8 week shutdown in autumn 2016. In view of this tight schedule, the planned commissioning steps and all high-level software needed to be developed and thoroughly tested in advance. Electron beam commissioning occupied the final 2 weeks of the shutdown, during which the injected electrons were captured and accumulated, the correct linear lattice was established, the nonlinear beam dynamics were studied, IDs were closed and the target 300 mA was achieved. This paper presents an overview of these activities.
* R.P. Walker et al., 'The Double-Double Bend Achromat (DDBA) Lattice Modification for the Diamond Storage Ring', Proc. IPAC 2014, MOPRO103, (2014) |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB095 | |
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| WEPAB096 | Diamond Light Source: A 10-year View of the Past and Vision of the Future | 2804 |
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| Diamond Light Source has been in regular operation for users for 10 years and so it is an appropriate moment to review the successes and challenges of the past, and also consider the vision for the next 10 years. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB096 | |
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| WEPAB097 | Modelling Two-Colour FEL with Wide Wavelength Separation and Individual Polarisation Tuning | 2808 |
| SUSPSIK016 | use link to see paper's listing under its alternate paper code | |
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| Free electron lasers (FELs) are currently enabling cutting edge research in chemistry, biology and physics. We use simulations to assess a new FEL capability that would add to the impressive repertoire of experiments made possible by the technology: a two-colour independent polarization mode, which allows for light pulses with variable temporal separation, individually tuneable polarisation, and widely separated wavelength. Simulations are carried out using the broad bandwidth FEL code Puffin, the results of which are used to discuss the radiation properties of the output. This scheme is applicable to existing and proposed facilities which feature undulators with variable ellipticity and gap. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB097 | |
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| WEPAB098 | Dielectrically-Loaded Waveguide as a Microwave Undulator for High Brillance X-Rays at 45 - 90 Kev | 2812 |
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| The HEM12 mode in a cylindrical, dielectrically-loaded waveguide provides E and H fields on the central axis that are significantly higher than the fields on the conducting walls. This structure, operating near the cutoff frequency of the HEM12 mode, spans a frequency range where the wavelength and phase velocity vary significantly. This property can be exploited to generate undulator action with short periods for the generation of high brightness x-rays. The frequency range of interest would be from 18 to 34.5-GHz. The goal would be to generate x-rays on the fundamental mode over a range of 45 to 90-kev. The tunability would be achieved by changing the source frequency while maintaining a constant on-axis equivalent undulator field strength of 0.5-T. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB098 | |
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| WEPAB099 | Development of the Manufacturing and QA Processes for the LCLS-II Injector Source VHF Electron Gun | 2815 |
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Funding: * This work is supported by the Office of Science, United States Department of Energy under DOE contract DE-AC02-05CH11231. The Linear Coherent Light Source-II (LCLS-II), a new free electron laser currently under construction at SLAC, requires a high repetition rate, high brightness, continuous wave electron source. Lawrence Berkeley National Laboratory (LBNL) has developed a design for a normal conducting VHF gun in response to that need and is responsible for its production and that of the associated beamline, with much of the fabrication done in-house. The 186 MHz copper cavity dissipates approximately 90 kW of RF power while maintaining a vacuum pressure on the order of 10-10 Torr. The gun is a critical component that requires a very high level of operational reliability to ensure uninterrupted availability for future system users. A quality assurance system to instruct manufacturing and change control is vital to ensure production of a gun that reliably meets physics requirements over an extended period of usage. This paper describes the QA processes developed for fabrication and assembly of the Injector Source electron gun along with results and lessons learned from their current implementation. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB099 | |
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| WEPAB101 | Lattice Optimization Using Jupyter Notebook on HPC Clusters | 2818 |
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Funding: Work supported by the Director Office of Science of the U. S. Department of Energy under Contract No. DE-AC02-05CH11231 Tracy accelerator simulation library was originally developed for the Advanced Light Source (ALS) design studies at LBNL in the late 1980's. It was originally written in Pascal, later ported to C++, and then to C#. It is still actively updated and currently used by the ALS Upgrade Project (ALS-U) to design and to optimize the lattice. Recently, it has been reconstructed to provide ease of use and flexibility by leveraging the quickly growing Python language. This paper describes our effort of porting it to Jupyter Notebook on our institutional High-Performance Computing (HPC) clusters. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB101 | |
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| WEPAB103 | On-Axis Swap-Out Injection R+D for ALS-U | 2821 |
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Funding: This work is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. The ALS-U upgrade promises to deliver diffraction limited performance throughout the soft x-ray range by lowering the horizontal emittance by a factor of 40 compared to the current ALS. One of the consequences of producing a small emittance is a small dynamic aperture, although the momentum acceptance will remain large enough for acceptable beam lifetime. To overcome this challenge, ALS-U will use on-axis swap-out injection to exchange bunch trains between the storage ring and an accumulator ring. On-axis swapout injection requires special fast pulsers and state-of-the-art stripline kicker magnets. This paper reports on the results of the on-axis swap-out injection R&D program, including beam tests of a complete stripline kicker/pulser system on the current ALS and the development of methods to speed up beam based commissioning after the upgrade shutdown. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB103 | |
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| WEPAB104 | Status of the Conceptual Design of ALS-U | 2824 |
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Funding: This work is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. The ALS-U upgrade promises to deliver diffraction limited performance throughout the soft x-ray range by lowering the horizontal emittance to about 50~pm resulting in 2-3 orders of brightness increase for soft x-rays compared to the current ALS. The design utilizes a multi bend achromat lattice with on-axis swap-out injection and an accumulator ring. One central design goal is to install and commission ALS-U within a short dark period. This paper summarizes the status of the conceptual design of the accelerator, as well as some results of the R&D program that has been ongoing for the last 3 years. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB104 | |
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| WEPAB105 | Design of the ALS-U Storage Ring Lattice | 2827 |
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Funding: The Advanced Light Source is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231 The Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory is proposing the upgrade of its synchrotron light source to reach soft x-ray diffraction limits within the present ALS footprint. The storage ring lattice design and optimization of this light source is one of the challenging aspects for this proposed upgrade. The candidate upgrade lattice needs not only to fulfill the physics design requirements such as brightness, injection efficiency and beam lifetime, but also to meet engineering constraints such as space limitations, maximum magnet strength as well as beamline port locations. In this paper, we will present the lattice design goals and choices and discuss the optimization approaches for the proposed ALS upgrade. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB105 | |
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| WEPAB108 | Angular Trajectory Kicks in a High-Gain Free-Electron Laser | 2830 |
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| In a free-electron laser (FEL), transverse momentum offsets (or kicks) are introduced either inadvertently (through wakefields or mis-steering of the electron beam) or as part of dedicated schemes that require off-axis radiation propagation. Studying the influence of this effect on the performance of machines such as LCLS-I/II is critical both from a tolerance point of view and for its practical applications. A theoretical analysis of a high-gain FEL driven by such a kicked beam will be presented, with a critical evaluation of previous studies. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB108 | |
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| WEPAB109 | Multipole Field Effects in a Transverse Gradient Undulator | 2833 |
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| Using a transverse gradient undulator (TGU) is one of the methods proposed in order to enable the utilization of electron beams with large energy spread (such as those from plasma-based accelerators) in a free-electron laser (FEL). Most of the analytical treatments of this scheme assume a linear variation of the undulator field with one of the transverse coordinates. While this assumption leads to a simplified and more tractable model, including higher-order multipoles allows us to offer a more complete and rigorous description of the system. In this paper, we investigate the magnetic field components of a TGU using both theory and simulation and explore the impact of higher-order multipoles on the FEL performance. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB109 | |
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| WEPAB114 | Potential Performance Limit of Storage Rings | 2836 |
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| The next generation of storage ring light sources will have significantly higher performance as multi-bend achromat cell structures are made practical with strong quadrupole and sextupole magnets. In principle the natural emittance can be made ever smaller with stronger magnets and larger rings until it reaches the true diffraction limit for hard X-rays. By considering the scaling laws of linear optics and nonlinear beam dynamics of storage rings and technical challenges, we explore the potential performance limit of future storage rings. A similar discussion may be applicable to the limit of energy frontier heavy-ion storage ring colliders. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB114 | |
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| WEPAB115 | Normal Conducting CW Transverse Crab Cavity For Producing Short Pulses In SPEAR3 | 2840 |
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Funding: This work was supported by DOE Contract No. DE-AC02-76SF00515. The ability to produce short pulse X-rays on the scale of 1-10 ps fwhm in the SPEAR3 storage ring light source would enable enhanced timing mode studies of dynamic processes in materials as they occur. The crab cavity approach appears to be optimal for SPEAR3 to produce short pulse X-rays. Furthermore, by using a two-frequency crabbing scheme, SPEAR3 would be able to produce short-pulse bunches while supplying the high average flux needed for regular users. While supercon-ducting RF (SCRF) technology could be a natural choice for the CW crab cavity, the deflecting voltage for SPEAR3 crabbing appears to be within reach of more affordable normal conducting RF (NCRF). In this paper, we present a preliminary NCRF CW crab cavity design for SPEAR3. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB115 | |
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| WEPAB116 | LCLS Injector Laser Shaping and Applications | 2844 |
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| In the Linear Coherent Light Source (LCLS) at SLAC, the injector laser plays an important role as the source of the electron beam for the Free Electron Laser (FEL). The beam emittance and FEL performance are highly related to the transverse shape of the injector laser. When the injector laser has hot spots and non-uniformities that can carry over to the electron beam and degrade electron emittance and FEL performance, it requires long hours of manual adjustment by laser engineers and strenuous machine tuneup. The injector laser shaping project at LCLS aims to have precise control of the driver laser transverse profile in order to produce arbitrary electron beam profiles, which will enable us to study effects of laser shape on beam emittance and FEL performances. We use a digital micromirror device (DMD) to manipulate the drive laser profile. In this paper, we briefly discuss the implementations of laser shaping at LCLS. We demonstrate two applications of laser shaping. We present results of using laser shaping to control the X-ray laser output via an online optimizer. We also show the photocathode quantum efficiency measurements across cathode surface using the DMD. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB116 | |
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| WEPAB118 | High Power Sub-Femtosecond X-Ray Pulse Study for the LCLS | 2848 |
| SUSPSIK017 | use link to see paper's listing under its alternate paper code | |
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| The desire to resolve sub-femtosecond electron dynamics has pushed FEL facilities to shorter pulse lengths. However, current short-pulse schemes provide low pulse energy and a gain-length limited lower bound on the pulse duration. The X-ray Laser-Enhanced Attosecond Pulses (XLEAP) project at SLAC is designed implement an Enhanced Self Amplified Spontaneous Emission (ESASE) scheme, which produces sub-fs current spikes by modulating and compressing the electron beam. We show through a series of Genesis simulations that the current spike is capable of producing sub-fs pulses with a peak power well above 100 GW. Space-charge induced beam chirp can decrease pulse lengths below 400 as, and multi-stage schemes can increase peak x-ray powers to around 1 TW. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB118 | |
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| WEPAB120 | Reproducibility Issues of NSLS-II Storage Ring and Modeling of the Lattice | 2851 |
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Funding: DOE Contract No: DE-SC0012704 As other facilities, in operating NSLS-II, we develop the lattices based on theoretical and simulation studies. Then the lattice is applied and the machine is optimized to have the desired design parameters. This process is very typical and works well and, furthermore, there is a general understanding that a model with the field measurement data is not realized as it is. However, it is evident that if the model represents the real machine close enough, there are lots of advantages we can take. One of them can be producing the lattice with changing environments. In this paper, we discuss the NSLS-II reproducibility status and efforts to construct the faithful realistic model. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB120 | |
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| WEPAB121 | Database for NSLS-II Accelerator Operation | 2854 |
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Funding: DOE Contract No: DE-SC0012704 NSLS-II is employing a database and corresponding user interfaces which are used for the accelerator data sharing and management. The database include operation related information such as beam optics parameters, magnet measurement data, survey data and operation summary. To improve the usability, other functionalities are also being added. However, due to the limited scope, the general expectation of the overall facility cannot not be met and, in order to solve the issue, we are in the process of adopting Component Database (ComponentDB) developed at Advanced Photon Source (APS). This paper shows the current status of the process. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB121 | |
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| WEPAB122 | Experimental Demonstration of Ballistic Bunching with Dielectric-Lined Waveguides at Pitz | 2857 |
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| We report on the experimental demonstration of ballistic bunching of photoinjected, nC-scale electron bunches at the PITZ facility. In the experiment, electron bunches emanating from the photocathode were directly focused into a mm-scale dielectric-lined waveguide. The wakefield excited by the bunch acts back onto itself, leading to an energy modulation, which at a relatively low energy of 6~MeV, is converted into a density modulation before entering the linac ∼ 1~m downstream. We discuss the basic theory, experimental layout and results. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB122 | |
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| WEPAB123 | A Phase Matching, Adiabatic Accelerator | 2861 |
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| Tabletop accelerators are a thing of the future. Reducing their size will require scaling down electromagnetic wavelengths; however, without correspondingly high field gradients, particles will be more susceptible to phase-slippage – especially at low energy. We investigate how an adiabatically-tapered dielectric-lined waveguide could maintain phase-matching between the accelerating mode and electron bunch. We benchmark our simple model with CST and implement it into ASTRA; finally we provide a first glimpse into the beam dynamics in a phase-matching accelerator. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB123 | |
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| WEPAB124 | Study of Hadron-Photon Colliders for Secondary Beam Generation | 2865 |
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We summarize the potentialities of combining two well developed technologies, which are advancing the frontiers of hadron colliders and of light sources, namely the hadron colliders for high energy physics, and the FELs for applied and fundamental science with light, towards the generation of secondary beams with unprecedented characteristics. The collision between their typical pulses of high energy protons and X-ray photons opens a collider scenario with potentials for luminosities in excess of 1038 s-1*cm-2, adequate to generate TeV-class pion, muon, neutrino and photon beams with very high phase space densities. We report results based on Monte Carlo simulations of such a hadron-photon collider*, aiming at qualifying the features of these secondary beams in view of experiments to be performed directly, or towards the design of a new kind of muon collider.
C. Curatolo, et al., Nuclear Instruments & Methods in Physics Research A (2016), http://dx.doi.org/10.1016/j. nima.2016.09.002i |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB124 | |
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| WEPAB125 | Crossbar H-Mode Drift-Tube Linac Design With Alternative Phase Focusing for Muon Linac | 2868 |
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Funding: This work was supported by JSPS KAKENHI Grant Number 15H03666. A crossbar H-mode (CH) drift-tube linac (DTL) is one of alternatives for a low velocity part in a muon linac at the J-PARC E34 experiment. It will accelerate muons from v/c = 0.08 to 0.28 at an operational frequency of 324 MHz. In order to achieve higher acceleration efficiency and make cost lower, an alternative phase focusing (APF) scheme is adopted. In this poster, dynamics and cavity designs with computer calculations will be presented. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB125 | |
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| WEPAB127 | EMuS Target Station Studies | 2871 |
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| The experimental muon source (EMuS) is a high-intensity muon source at China Spallation Neutron Source (CSNS), aiming to combine muSR applications, R&D efforts for a future muon-decay based neutrino beam, and neutrino cross-section measurements. The proton beam has 4 kW of power and is provided by the rapid cycling synchrotron (RCS) of CSNS to a capture system that consists of an adiabatic superconductive solenoid with a maximum field of 5 T and a graphite target located inside the first coil, in order to maximize muons/pions capture and reduce their transverse momentum. In this article we present the challenging target system and the optimization studies that led to the current 4-coil/3-step design. The challenge arises from the necessary extraction of the spent proton beam along the downstream area of the capture solenoid through a hole, in order to separate it from the muons and pions. In addition, shielding studies are presented in order to examine the effectiveness of the shields on the coils and the low radiation damage expected in the system. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB127 | |
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| WEPAB129 | Study of Ionization Cooling with the MICE Experiment | 2874 |
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| The international Muon Ionization Cooling Experiment (MICE) will demonstrate the ionization cooling of muons; the only known technique that can provide high brightness muon beams suitable for applications such as a Neutrino Factory or Muon Collider. MICE is underway at the Rutherford Appleton Laboratory and has recently taken the data necessary to characterise the physical processes that underlie the ionization-cooling effect. Measurements of the change in normalised transverse amplitude are presented in two configurations. The measurements of the ionization-cooling effect are discussed. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB129 | |
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| WEPAB130 | First Results from MICE Step IV | 2878 |
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Funding: STFC, DOE, NSF, INFN, CHIPP and more Muon beams of low emittance provide the basis for the intense, well characterised neutrino beams of the Neutrino Factory and for lepton-antilepton collisions at energies of up to several TeV at a Muon Collider. The international Muon Ionization Cooling Experiment (MICE) will demonstrate ionization cooling - the technique by which it is proposed to reduce the phase-space volume occupied by the muon beam. MICE is being constructed in a series of Steps. The configuration currently in operation at the Rutherford Appleton Laboratory is optimised for the study the properties of liquid hydrogen and lithium hydride that affect cooling. The data taken in the present configuration have been partially analyzed and the available results will be described in detail. submitted by the Speakers Bureau of the collaboration, in charge of finding later a member to prepare and present the contribution |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB130 | |
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| WEPAB131 | Layout of the MICE Demonstration of Muon Ionization Cooling | 2881 |
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Funding: STFC, DOE, NSF, INFN, CHIPP and more Muon beams of low emittance provide the basis for the intense, well-characterised neutrino beams necessary to elucidate the physics of flavour at the Neutrino Factory and to provide lepton-antilepton collisions up to several TeV at the Muon Collider. The international Muon Ionization Cooling Experiment (MICE) will demonstrate muon ionization cooling, the technique proposed to reduce the phase-space volume occupied by the muon beam at such facilities. In an ionization-cooling channel, the muon beam traverses a material (the absorber) loosing energy, which is replaced using RF cavities. The combined effect is to reduce the transverse emittance of the beam (transverse cooling). The configuration of MICE required to deliver the demonstration of ionization cooling is presently being prepared in parallel to the execution of a programme designed to measure the cooling properties of liquid-hydrogen and lithium hydride (Step IV). The design of this final cooling demonstration will be presented together with a summary of the performance of each of its components and the cooling performance of the experiment. submitted by the Speakers Bureau of the collaboration, in charge of finding later a member to prepare and present the contribution |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB131 | |
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| WEPAB132 | Research Program and Recent Results at the Argonne Wakefield Accelerator Facility (AWA) | 2885 |
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Funding: Work supported by the U.S. Department of Energy under contract No. DE-AC02-06CH11357 We give an overview of the research program at the Argonne Wakefield Accelerator Facility (AWA), including some highlights of recent experiments. The AWA facility is dedicated to the study of beam physics and the development of technology for future particle accelerators. Two independent electron linacs are used to study wakefield acceleration: 70 MeV high charge electron bunches of up to 100 nC are used to drive wakefields, which can be probed by bunches originating from the same linac or from the 15 MeV linac. Recent Two-Beam-Acceleration (TBA) experiments operating at 11.7 GHz reached accelerating gradients of up to 150 MV/m. No indication of witness beam quality degradation was observed, and bunch charge was preserved during the acceleration process. Two identical TBA setups were used in series in order to demonstrate staging capabilities. Dielectric loaded structures operating at 26 GHz are also used in TBA experiments. Another main thrust of the research program consists of exploring and developing techniques to manipulate the phase space of electron bunches. These efforts include bunch shaping and the exchange of emittances in the transverse and the longitudinal phase spaces |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB132 | |
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| WEPAB133 | A Wedge Absorber Experiment at MICE | 2888 |
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| Emittance exchange mediated by wedge absorbers is required for longitudinal ionization cooling and for final transverse emittance minimization for a muon collider. A wedge absorber within the MICE beam line could serve as a demonstration of the type of emittance exchange needed for 6-D cooling, including the configurations needed for muon colliders, as well as configurations for low-energy muon sources. Parameters for this test are explored in simulation and possible experimental configurations with simulated results are presented. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB133 | |
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| WEPAB134 | Progress on Beam-Plasma Effect Simulations in Muon Ionization Cooling Lattices | 2891 |
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Funding: Work supported by the U.S. Department of Energy. New computational tools are essential for accurate modeling and simulation of the next generation of muon-based accelerators. One of the crucial physics processes specific to muon accelerators that has not yet been simulated in detail is beam-induced plasma effect in liquid, solid, and gaseous absorbers. We report here on the progress of developing the required simulation tools and applying them to study the properties of plasma and its effects on the beam in muon ionization cooling channels. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB134 | |
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| WEPAB135 | Novel Implementation of Non-parametric Density Estimation in MICE | 2895 |
| SUSPSIK026 | use link to see paper's listing under its alternate paper code | |
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Funding: Work supported by the U.S. Department of Energy under contract No. DE-AC05-06OR23100. Cooled muon beams are essential to enable future Neutrino Factory and Muon Collider facilities. The international Muon Ionization Cooling Experiment (MICE) aims to demonstrate muon beam cooling through ionization energy loss in material. A figure of merit for muon cooling in MICE is the transverse root-mean-square (RMS) emittance reduction and to measure this, the individual muon positions and momenta are reconstructed using two scintillating-fiber tracking detectors housed in spectrometer solenoid modules. The reconstructed positions and momenta before and after a low-Z absorbing material are then used for constructing the covariance matrix and measuring normalized transverse RMS emittance of MICE muon beam. In this study, the direct measurement of phase-space density and volume as measures of the efficacy of muon beam cooling in MICE, using the density estimation techniques is described. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB135 | |
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| WEPAB137 | Cold Muonium Negative Ion Production | 2898 |
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| Charged muons as Muonium negative ions (consisting of positive Mu-meson and 2 electrons) have affinity S=0.75 eV. Muonium have ionization energy I=13.6 eV. Muonium negative ions were observed in 1987 [10, 11] by interaction of muons with a foil. In these work an efficiency of transformation of mu mesons to negative musonium ions were very low 10-4. However, with using Tungsten or palladium single crystal with deposition cesium it can be improved up to 40-50%. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB137 | |
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| WEPAB138 | Prototyping High-Gradient mm-Wave Accelerating Structures | 2902 |
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| We present single-cell accelerating structures designed for high-gradient testing at 110 GHz. The purpose of this work is to study the basic physics of ultrahigh vacuum RF breakdown in high-gradient RF accelerators. The accelerating structures are pi-mode standing-wave cavities fed with a TM01 circular waveguide. The structures are fabricated using precision milling out of two metal blocks, and the blocks are joined with diffusion bonding and brazing. The impact of fabrication and joining techniques on the cell geometry and RF performance will be discussed. First prototypes had a measured Qo of 2800, approaching the theoretical design value of 3300. The geometry of these accelerating structures are as close as practical to single-cell standing-wave X-band accelerating structures more than 40 of which were tested at SLAC. This wealth of X-band data will serve as a baseline for these 110 GHz tests. The structures will be powered with short pulses from a MW gyrotron oscillator. RF power of 1 MW may allow us to reach an accelerating gradient of 400 MeV/m. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB138 | |
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