| Paper | Title | Page |
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| TUPMN001 | The Australian Synchrotron Project | 911 |
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| Funding for the Australian Synchrotron, a 3 GeV synchrotron light source, was announced by the Victorian State Government in January 2003, and six months later bulldosers moved onto the green-field site in the South-East suberbs of Melbourne. After a remarkably fast construction and installation period the accelerators that form the heart of the faclity were commissioned in 2006. Installation of the first five beamlines will commence in January 2007 and it is expected that the first experiments will be carried out in April. In this presentation we give an update on the status of the facility and present highlights of the commissioning activities. | ||
| TUPMN003 | Lifetime Contribution Measurements at the Australian Synchrotron | 914 |
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| There are always a number of factors that contribute to the lifetime of a stored particle beam. Measurements presented here show the relative importance of these effects during the commissioning of the Australian Synchrotron storage ring. | ||
| TUPMN004 | Final Adjustment of the Magnetic Field of the LNLS VUV Undulator. | 917 |
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| The first insertion device built at LNLS was an elliptically polarized undulator, designed to cover the vacuum ultraviolet and the soft X-ray spectrum. Its magnetic characterization was done using two techniques: Hall probes, for local field measurements, and rotating coil, operating in a way similar to flip-coil, to determine the integrated multipoles. Final results for the phase errors as well as the procedures used to correct the integrated multipoles are presented. | ||
| TUPMN005 | Optimizing Beam Brightness at the Canadian Light Source | 920 |
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| The Canadian Light Source (CLS) storage ring has been operating routinely since commissioning was completed in the spring of 2004. Since that time the storage ring parameters have been adjusted in efforts to increase the brightness of the source. This includes changes to the operating point, reducing the transverse coupling and optimizing the dispersion at the source points. Depending on the photon energy brightness from undulators is increased by reducing the beam size or reducing the emittance. This is achieved with higher tunes which both decrease the emittance and beta-functions. Dispersion at the undulators can be optimized to minimize the effective beam emittance or beam size. Vertical coupling can be adjusted to less than 0.1% by both reducing the vertical dispersion and transverse coupling from the horizontal motion. | ||
| TUPMN006 | Apple-II and TESLA FEL Undulators at Danfysik A/S | 923 |
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Danfysik A/S* has recently designed and produced a high-performance Apple-II type insertion device for the Australian Synchrotron Project, with low variation of the first integrals versus gap and phase, and minimal phase error. Thanks to software assistance, and an unconventional keeper design, the total time spent on magnet mounting, shimming and final magnetic testing was reduced to 5 weeks. Furthermore, in order to negate the second-order tune effect of the insertion device on the dynamic aperture, ESRF-type tune shims were designed and installed. Danfysik is manufacturing and assembling one of three undulator prototypes for the TESLA FEL project at DESY. The prototype is based on a design made by DESY, but with changes implemented by Danfysik. A major part of the project is to make an industrial study that will recommend where design efforts on the next prototype generation shall be focused.
* http://www.danfysik.com/ |
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| TUPMN007 | Final Commissioning Results from the Injection System for the Australian Synchrotron Project | 926 |
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| Danfysik has delivered a full-energy turn-key injection system for the Australian Synchrotron. The system consists of a 100 MeV linac, a low-energy transfer beamline, a 130 m circumference 3-GeV booster, and a high energy transfer beamline. The booster lattice was designed to have many cells with combined-function magnets (dipole, quadrupole and sextupole fields) in order to reach a very small emittance. The injection system has been commissioned and found to deliver a beam with an emittance of less than 30 nm, and currents in single- and multi-bunch mode in excess of 0.5 and 5 mA, respectively, fulfilling the contractual performance specifications. The repetition frequency is 1 Hz. Results from the commissioning of the system will be presented. | ||
| TUPMN008 | Commissioning of the First Insertion Devices at SOLEIL | 929 |
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| The 2.75 GeV storage ring of the SOLEIL third generation light source in France consists of 16 cells and 24 straight sections (4x12m,12x7m, 8x3.6m) for a total circumference of 357 m. 24 insertion devices are planned for providing high brillance radiation from UV to hard X ray. They consist of adjustable polarisation sources in the UV-soft X ray (electromagnetic devices of periods 640 mm and 256 mm, APPLE-II of periods ranging between 80 and 34 mm, and one EMPHU) and planar devices for the production of hard X ray (in vacuum undulators of period 20 or 26 mm and one in vacuum wiggler). During the commissioning of the presently installed seven insertion devices (HU640, 2xHU256, 2 HU80, 2xU20), the effects on the beam have been studied (closed orbit distortions, tune shifts,..), compared with the expectations from magnetic measurements in laboratory, and compensated using feed forward local correctors. The radiation observed on the first photon diagnostic at the beamlines is also analysed. | ||
| TUPMN009 | Commissioning of the SOLEIL Synchroton Radiation Source | 932 |
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| The French 3rd generation synchrotron light source, SOLEIL, was successfully commissioned in 2006. The Linac and the Booster are operational at their design performances. During the early phase of the storage ring commissioning, the essential design parameters were reached very quickly while the project incorporates some innovative techniques such as the use of a superconducting RF cavity, solid state RF amplifiers, NEG coating for all straight parts of the storage ring and new BPM electronics. Prior to the start of the commissioning, some insertion devices and most of the insertion devices low gap vacuum vessels, including 10 mm inner vertical aperture vessels for the Apple-II type, were installed on the ring. The main results of the commissioning will be reviewed here, including discussion on diagnostics performances, orbit stability and control, optics correction, Top-up and the challenges in achieving operational status. The 10 beamlines of phase 1 are now under commissioning and regular user operation will start by spring 2007. | ||
| TUPMN010 | Latest Developments of Insertion Devices at ACCEL Instruments | 935 |
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| ACCEL Instruments GmbH has designed, manufactured, assembled, and tested several insertion devices for many synchrotron light sources and free electron lasers around the world. Besides the superconducting (sc) wavelength shifters, sc-wigglers and sc-Undulators, ACCEL has entered the pure permanent magnet based insertion device market. The latest progress of the ID group was the production of 6 identical PPM Undulators for the SPARC FEL project in Frascati (Italy), the production of a prototype Undulator and an industrial study on large scale Undulator production for the European X-FEL project in Hamburg (Germany). ACCEL has signed a know how and license agreement with the ID group of the ESRF in order to be able to supply customers with high quality insertion devices in short delivery times. Therefore ACCEL has setup an standard ESRF 7 m granite measuring bench. Design efforts, measurement techniques, and performance results will be presented. | ||
| TUPMN012 | STARS - A Two-Stage High-Gain Harmonic Generation FEL Demonstrator | 938 |
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Funding: Bundesministerium fur Bildung und Forschung and the Land Berlin BESSY is proposing a demonstration facility, called STARS, for a two-stage high-gain harmonic generation free electron laser (HGHG FEL). STARS is planned for lasing in the wavelength range 40 to 70 nm, requiring a beam energy of 325 MeV. The facility consists of a normal conducting gun, three superconducting TESLA-type acceleration modules modified for CW operation, a single stage bunch compressor and finally a two-stage HGHG cascaded FEL. This paper describes the faciliy layout and the rationale behind the operation parameters. |
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| TUPMN013 | Dynamic Multipole Shimming of the APPLE Undulator UE112 | 941 |
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| The dynamic off axis field integrals of the BESSY UE112 are of the order of 3 Tmm. They reduce the dynamic aperture significantly which is not tolerable for top-up operation. The dynamic multipoles have successfully been shimmed for the elliptical mode using distributed Fe-shims. In the inclined mode the multipoles are minimized actively with rotatable permanent magnets which are adjusted dependent on gap and phase position. The dynamic properties of the unshimmed and the shimmed device have been simulated using an analytic model for the field description and a generating function algorithm for tracking. | ||
| TUPMN014 | Commissioning of the 100 MeV Racetrack Microtron of the Metrology Light Source | 944 |
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Funding: Physikalisch-Technische Bundesanstalt, Abbestr. 2 - 12, 10587 Berlin, Germany In 2003, the Metrology Light Source (MLS) was approved, a dedicated low energy electron storage ring of the Physikalisch-Technische-Bundesanstalt (PTB), the German national metrology institute. Design, construction and operation of the MLS are realized by BESSY, based on the PTB requirements for a permanent accessible radiometry source, optimized for the spectral range between UV up to VUV. The MLS is tunable in energy between 200 MeV and 600 MeV. Based on the experiences at BESSY, a highly stable and reliable Race Track Microtron for injection was realized by Danfysik. The commissioning of the 100 MeV microtron at the MLS started in December 2006. The concept and construction as well as the main parameters of the microtron are introduced. |
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| TUPMN015 | First Commissioning Results of the Metrology Light Source | 947 |
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Funding: Physikalisch-Technische Bundesanstalt, Abbestr. 2 - 12, 10587 Berlin, Germany The Physikalisch-Technische Bundesanstalt (PTB), the German national metrology institute, has built an electron storage ring in close cooperation with BESSY for energies between 200 MeV and 600 MeV. This storage ring, named Metrology Light Source (MLS), will mainly be used for radiometry and can be operated as a primary source standard. The spectral range of the MLS is optimized for UV, EUV and also for Terahertz radiation. Commissioning is planed for May 2007. First MLS commissioning results will be reported. |
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| TUPMN016 | Upgrade of the BESSY Femtoslicing Source | 950 |
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| The BESSY femtoslicing source as the first undulator-based source has succesfully demonstrated its capabilities of providing ~100 fs x-ray pulses in an energy range from 300 to 1400 eV with linear and circular polarisation. With this type of slicing source exhibiting an excellent signal-to-noise ratio, the number of detected photons at the user frontend is still limited to ~103 / sec. Several improvements are underway to increase the photon flux and to improve the stability of the source. An upgrade of the present laser system will increase the pulse repetition rate from 1 to 3 kHz. Furthermore, a new evacuated laser beam path will be implemented to provide higher pointing stability and an automated postion feedback. The benefits and limitations of these improvements will be discussed, and new measurements will be presented. | ||
| TUPMN017 | ''Jitter Free'' FEL Pulses for Pump and Probe Experiments | 953 |
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Funding: Bundesministerium fur Bildung und Forschung and the Land Berlin The cascaded High Gain Harmonic Generation (HGHG) scheme proposed for the BESSY-FEL contains an inherent potential for providing jitter free radiation pulses for pump and probe experiments. In an HGHG stage an energy modulation is imprinted to the electron beam by a seeding radiation. A dispersive section converts this energy modulation to a spatial modulation which is optimized for a particular harmonic. The subsequent radiator is optimized for this harmonics and generates radiation with high power which is used as seeding radiation for the next stage. After passage through the modulator, the seeding radiation become redundant and can be separated from the prebunched electrons using a deflecting dispersive chicane. This radiation and the final FEL output will have a fixed temporal separation as the first one is the driving seeding radiation for the second one. Using the planned test facility for HGHG scheme at BESSY as an example, we present simulation studies for a sequences of two jitter free pump and probe pulses including the deflecting chicane and a suitable beam line. |
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| TUPMN018 | Dark Current Transport in the FLASH Linac | 956 |
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| The free electron laser facility FLASH at DESY Hamburg operates a low-emittance photoinjector and several acceleration modules with superconducting cavities to produce a high quality electron beam of up to 700 MeV. Since few months, the accelerator is routinely operated with its design RF pulse length of 800 μs instead of the prior length of 70-200 μs. As a result, the activation of components due to dark current emitted by the gun has reached critical proportions. To improve the understanding of dark current transport through the linac, simulations have been conducted with the Astra tracking code. The generated phase space distributions are compared against a detailed 3-dimensional aperture model of the machine with the newly developed ApertureLib toolkit. The results are in agreement with direct measurements of the dark current and with the observed activities. | ||
| TUPMN020 | Velocity Bunching at the European XFEL | 959 |
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| This paper explores the possibility to employ velocity bunching in the first RF module of the European XFEL to increase the peak current at the injector exit. The current increase will reduce the total longitudinal bunch compression factor and loosen rf jitter tolerances by the same amount. The relation between rf tolerances and micro-bunching instability gain is discussed and the injector optimization for cases of velocity bunching to 100A and 200A peak current are presented in detail. Finally, plans for velocity bunching experiments at the FLASH facility (Free Electron Laser in Hamburg) are laid out. | ||
| TUPMN021 | Status of Nb-Pb Superconducting RF-Gun Cavities | 962 |
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| We report on the progress in the status of an electron RF-gun made of two superconductors: niobium and lead. The presented design combines the advantages of the RF performance of bulk niobium superconducting cavities and the reasonably high quantum efficiency of lead. Measured values of quantum efficiency for lead at 2K and the RF-performance of three half-cell niobium cavities with the lead spot exposed to high electric fields are reported in this contribution. | ||
| TUPMN023 | Status of the Optical Replica Synthesizer at FLASH | 965 |
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A novel laser-based method to measure the longitudinal profile of ultrashort electron bunches, known as Optical Replica Synthesizer*, will be implemented at the free-electron laser FLASH at DESY. The paper describes its technical layout and the status of the project.
* E. Saldin, E. Schneidmiller, M. Yurkov, NIM A 539 (2005), 499 |
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| TUPMN024 | Measurements of the Beam Heat Load in the Cold Bore Superconductive Undulator Installed at ANKA | 968 |
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| The beam heat load in the cold bore superconductive undulator installed at ANKA has been monitored for almost two years. The possible sources of the observed heat load as synchrotron radiation from upstream magnets, image currents, photo-excited electrons and ions will be discussed and compared with the experimental results. | ||
| TUPMN026 | Conditioning of a New Gun Cavity Towards 60 MV/m at PITZ | 971 |
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Funding: This work has partly been supported by the European Community, contracts RII3-CT-2004-506008 and 011935, and by the 'Impuls- und Vernetzungsfonds' of the Helmholtz Association, contract VH-FZ-005. Beginning 2007, a new gun cavity will be installed at the photo injector test facility at DESY in Zeuthen (PITZ). It will be conditioned towards gradients as high as 60 MV/m. This gradient is required for the operation of the European XFEL. Results from the conditioning for high peak power and high duty cycle will be reported. |
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| TUPMN028 | The New Photoinjector for the Fermi Project | 974 |
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| FERMI@ELETTRA is a single-pass FEL user facility covering the spectral range 100 10 nm. It will be located near the Italian third generation Synchrotron Light Source facility ELETTRA and will make use of the existing 1.0 GeV normal conducting Linac. To obtain the high beam brightness required by the project, the present Linac electron source will be substituted with a photocathode RF gun now under development in the framework of a collaboration between Sincrotrone Trieste (ST) and Particle Beam Physics Laboratory (PBPL) at UCLA. The new gun will use an improved design of the 1.6 cell accelerating structure already developed at PBPL, scaled to 2998 MHz. We expect that the new gun design will allow a beam brightness increase by a factor 3-4 over the older version of the device. Some technical choices of the new design, including the enhancement of the mode separation, removal of the RF tuners, full cell symmetrization to limit the dipole and quadrupole RF field as well as an improved solenoid yoke design for multipole field corrections, will be discussed. | ||
| TUPMN029 | Linac Upgrading Program for the Fermi Project : Status and Perspectives | 977 |
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| FERMI@ELETTRA is a soft X-ray forth generation light source under development at the ELETTRA laboratory. It will be based on the existing 1.0 GeV Linac, revised and upgraded to fulfil the stringent requirements expected from the machine. The overall time schedule of the project is very tight and ambitious, foreseeing to supply 10 nm photons to users within 2010. Here the machine upgrading program and the ongoing activities are presented and discussed. | ||
| TUPMN030 | Development of the Mechanical Structure for FERMI@elettra APPLE II Undulators | 980 |
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| A conceptual design study of the mechanical structure for the APPLE II undulators of the FERMI@elettra project has been carried using FEM structural analysis program and multiobject optimization software. In this paper the undulator performance, taking into account the predicted mechanical deformations due to the varying magnetic forces, will be evaluated and the resulting magnetic field and optical phase error discussed. | ||
| TUPMN032 | The New Elettra Booster Injector | 983 |
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| The new full energy injector for Elettra is under construction. The complex is made of a 100 MeV linac and a 2.5 GeV synchrotron, at 3 Hz repetition rate. With the new injector top-up operation shall be feasible. In the first semester of 2007 the machine assembly has been performed. In Summer 2007 the commissioning is scheduled, while in Fall 2007 the connection to the Storage Ring is planned. The status of the project will be reported in this paper. | ||
| TUPMN034 | Comparison Between SPARC E-Meter Measurements and Simulations | 986 |
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| For the SPARC photoinjector commissioning the emittance compensation process has been studied experimentally under different beam conditions (variation of charge, spot size, beam shape…) by a novel device called "emittance-meter", consisting in a movable emittance measurement system based on the 1D pepper pot method scanning a region 1.2 m long downstream the RF-gun. The results of a detailed comparison between the measurements and beam dynamics simulations performed by the different codes(PARMELA, HOMDYN, TREDI) employed for SPARC design are presented and discussed here. | ||
| TUPMN035 | Generation of a Multipulse Comb Beam and a Relative Twin Pulse FEL | 989 |
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| A radiofrequency electron gun joined to a compressor generates trains of THz subpicosecond electron pulses. Assuming a prompt electron emission, the laser train generates a train of electron disks at the cathode, then the disk train evolves towards a slug with a slight density modulation but also with a peculiar sawtooth energy modulation. This kind of energy modulation is transformed into a density modulation by a velocity bunching compressor recovering at a good extent the initial intensity beam profile. We study here through simulations the process looking to its characteristics as function peak and frequency characteristics of the laser and the parameters of the accelerator. | ||
| TUPMN036 | Laser and RF Synchronization Measurements at SPARC | 992 |
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Funding: Work supported by the EU Commission in the sixth framework programme, contract no. 011935 - EUROFEL. The SPARC project consists in a 150 MeV B-band, high-brilliance linac followed by 6 undulators for FEL radiation production at 530 nm. The linac assembly has been recently completed. During year 2006 a first experimental phase aimed at characterizing the beam emittance in the first 2m drift downstream the RF gun has been carried out. The low level RF control electronics to monitor and synchronize the RF phase in the gun and the laser shot on the photocathode has been commissioned and extensively tested during the emittance measurement campaign. The laser synchronization has been monitored by measuring the phase of the free oscillation of an RF cavity impulsively excited by the signal of a fast photodiode illuminated by the laser shot. Phase stability measurements are reported, both with and without feedback correction of the slow drifts. A fast intra-pulse phase feedback system to reduce the phase noise produced by the RF power station has been also positively tested. |
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| TUPMN037 | Power Tests of a PLD Film Mg Photo-cathode in a RF Gun | 995 |
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| Metallic film photo-cathodes are rugged, have a fast response and good emission uniformity. Mg has also a relevant Quantum Efficiency in the near UV. A cathode suitable for a 1.5 cells S-band RF gun has been produced by depositing an Mg film on Cu by Pulsed Laser Deposition technique. After different optimizations, stable good results have been reached in the low field measurement scenario. A sample was deposited on a gun flange and tested in the 1.6 cell injector at UCLA Pegasus facility to prove cathode resistence in a high field environment. The results are described. | ||
| TUPMN038 | Coherent Cherenkov Radiation as a Temporal Diagnostic for Microbunched Beams | 998 |
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| Cherenkov radiation of a relativistic e-beam traversing a thin section of aerogel is analized, putting the stress on the coherent contribution due to the intra-beam, transverse and longitudinal structure. The use of this tool as a temporal diagnostic for micro-bunched beams makes possible to improve the amount of collected power at the microbunching frequency several orders of magnitude more respect to the uncoherent Cherenkov contribution. The non-idealities of a real beam are taken in account, and some techniques aimed on enhancing the coherent part of radiation are proposed and analized analitically and through simulation codes. | ||
| TUPMN039 | Status of the SPARC-X Project | 1001 |
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| SPARC-X is a two branch project consisting in the SPARC test facility dedicated to the development and test of critical subsystems such as high brightness photoinjector and a modular expandable undulator for SASE-FEL experiments at 500 nm with seeding, and the SPARX facility aiming at generation of high brightness coherent radiation in the 3-13 nm range, based on the achieved expertise. The projects are supported by MIUR (Research Department of Italian Government) and Regione Lazio. SPARC has completed the commissioning phase of the photoinjector in November 2006. The achieved experimental results are here summarized together with the status of the second phase commissioning plans. The SPARX project is based on the generation of ultrahigh peak brightness electron beams at the energy of 1 and 2 GeV generating radiation in the 3-13 nm range. The construction is at the moment planned in two steps starting with a 1 GeV Linac. The project layout including both RF-compression and magnetic chicane techniques has been studied and compared, together with the feasibility of a mixed s-band and x-band linac option. | ||
| TUPMN040 | Drive Laser System for SPARC Photoinjector | 1004 |
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| In this paper we report the progress of the SPARC photoinjector laser system. In the high brightness photoinjector the quality of the electron beam is directly related to the photocathode drive laser. In fact the 3D distribution of the electron beam is determined by the incoming laser pulse. The SPARC laser is a 10 Hz frequency-tripled TW-class Ti:Sa commercial system. To achieve the required flat top temporal shape we perform a manipulation of the laser spectrum in the fundamental wavelength and in the third harmonic. The optical transfer-line has been implemented to limit the pointing instabilities and to preserve to the cathode the temporal and spatial features of the laser pulse. We present the recorded performances in terms of time pulse shape and rf-to-laser synchronization. | ||
| TUPMN041 | Three Dimensional Analysis of the X-Radiation Produced by a Collective Thomson Source | 1007 |
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| A set of 3-D equations that describes the collective head to head interaction between a laser pulse and a relativistic electron beam is presented and solved. The relevant dispersion relation is studied, as well as the gain properties of the system. The FEL instability dominates the radiation process. The radiation emitted is characterized by short wavelength, thin spectrum and high coherence. The most important three-dimensional effects are the emittance of the beam and the transverse distribution of the laser energy. The production of radiation wavelengths of 12 nm, 1nm, and 1 Angstron are presented. | ||
| TUPMN042 | Simulation Study of Resistive-wall Beam Breakup for ERLs | 1010 |
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For future ERL-based light sources, average beam current is required to be up to 100 mA. Such a high-current multi-bunch beam may generate and cumulate strong long-range wake-fields by interaction with accelerator components such as superconducting cavities and vacuum ducts, and as a result, strong beam breakup(BBU) may occur. Resistive-wall BBU due to narrow and resistive vacuum ducts has been hardly studied, though the effects of BBU due to HOMs of superconducting cavities were much investigated. Asymptotic expressions of transverse resistive-wall BBU were derived for a beam that passes through a uniform resistive pipe under uniform external focusing*. However the expressions are valid only for limited parameter ranges and initial conditions. Therefore we have developed a computer simulation program to study transverse multi-bunch resistive-wall BBU more minutely and generally. In this paper, we will present the simulation results obtained by the simulation program and also compare them with the asymptotic expressions.
* J. M. Wang and J. Wu, PRST-AB 7, 034402(2004) |
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| TUPMN043 | Graphite Heater Optimized for a Low-emittance CeB6 Cathode | 1013 |
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| We developed a thermionic cathode assembly using a single-crystal CeB6 emitter for the x-ray free electron laser project at SPring-8. The CeB6 cathode has excellent emission properties, i.e., smooth surface, high emission density, uniform emission density, and high resistance to contamination. A cylindrical graphite heater was developed to heat the cathode up to the operational temperature as high as 1800 K. At this temperature, a 500 keV pulsed electron beam with more than 1 A peak current can be extracted from the small surface area (3 mm diameter). In this conference, we will report the design detail and operational experience of the graphite heater for the CeB6 cathode. | ||
| TUPMN044 | Status of R&D Efforts Toward the ERL-based Future Light Source in Japan | 1016 |
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| Energy Recovery Linacs (ERL), based on superconducting accelerators, are one of the most promising synchrotron light sources in future. The KEK and the JAEA, in collaboration with the ISSP, the UVSOR, and the SPring-8, are considering to realize together the ERL-based next-generation light source in Japan. To establish key technologies for that, active R&D efforts started. The R&D program includes the developments of ultra-low-emittance photocathode guns and of superconducting cavities, as well as experimental proofs of accelerator-physics issues at the ERL test facility, which will be built at the KEK campus. We are currently working on constructing a prototype photocathode gun, on designing superconducing cavities, and on designing a prototype ERL. The current plan of the prototype ERL comprises a full injector linac, one or two cryomodules for the main linac, and the beam return loop, which can be operated at beam energies from 60 to 160 MeV. The up-to-date R&D status will be reported. | ||
| TUPMN045 | PF-Ring and PF-AR Operational Status | 1019 |
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| In KEK, we have two synchrotron light sources which were constructed in the early 1980s. One is the Photon Factory storage ring (PF-ring) and the other is the Photon Factory advanced ring (PF-AR). The PF-ring is usually operated at 2.5 GeV and sometimes ramped up to 3.0 GeV to provide photons with the energy from VUV to hard X-ray region. The PF-AR is mostly operated in a single-bunch mode of 6.5 GeV to provide pulsed hard X-rays. Operational performances of them have been upgraded through several reinforcements. After the reconstruction of the PF-ring straight sections from March to September 2005, two short-gap undulators were newly installed. They allow us to produce higher brilliant hard X-rays even at the energy of 2.5 GeV. At present we are going to prepare a top-up operation for the PF-ring. In the PF-AR, new tandem undulators have been operated in one straight section since September 2006 to generate much stronger pulsed hard X-rays for the sub-ns resolved X-ray diffraction experiments. In this conference, we report operational status of the PF-ring and the PF-AR including other machine developments. | ||
| TUPMN046 | Quadrupole HOM Damping with Eccentric-fluted Beam Pipes | 1022 |
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| HOM damping is important for superconducting cavities, especially for high current CW machines such as ERLs. The lower Q-values of HOMs lead to the lower requirement of a refrigerator system and the higher beam current against HOM BBU. Enlarged beam pipes, which have lower cutoff frequencies, are effective to damp HOMs of monopole and dipole, but insufficient for HOMs of quadrupole which have high cutoff frequencies. An eccentric-flute is proposed to damp the HOMs of quadrupole. The eccentric-flute is formed by displacing the flute from the center of the beam pipe and/or by jackknifing around the midpoint of the flute to couple two degenerate modes. The eccentric-flute acts as a mode converter from quadrupole to dipole of the lower cutoff frequency so that the RF power can propagate through the beam pipe. The result of calculation with MAFIA and measurement of a cold model with the eccentric-flute are presented. | ||
| TUPMN047 | W-band Electromagnetic Wave Undulator for AIST 800 MeV Electron Storage Ring TERAS | 1025 |
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| An electromagnetic-wave undulator based on a quasi-optical resonator operated in higher order TE mode is proposed to generate monochromatic X-rays. We plan to install it to an 800MeV electron storage ring TERAS of AIST. Mode propagation in the resonator was analysed with an electromagnetic-wave simulation code MAFIA and HFSS. Design parameters for the undulator operated in W-band (95 GHz) was presented. The peak electric field along the electron orbit was estimated to be 130 kV/m when we fed 1 kW of 95 GHz electromagnetic wave. The estimated X-ray flux density was 1 x 1011 photons/sec/mrad2/A for 3.4 keV X-rays. | ||
| TUPMN048 | Recent Developments at UVSOR-II | 1028 |
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| UVSOR, a 750 MeV synchrotron light source of 53m circumference had been operated for more than 20 years. After a major upgrade in 2003, this machine was renamed to be UVSOR-II. The ring is now routinely operated with low emittance of 27 nm-rad and with four undulators, two in-vacuum ones and two variably polarized ones. The injector and the beam transport line are being upgraded to be compatible with full energy injection, preparing for the top up operation in near future. A resonator type free electron laser is successfully operational in very wide range, from visible to deep UV, with high average power exceeding 1 W. A femto-second laser bunch slicing system was constructed by utilizing a part of the FEL system. Intense coherent terahertz radiation was successfully produced by the slicing. Coherent harmonic generation was successfully demonstrated by using the same laser system. | ||
| TUPMN049 | Improvement of Soft X-ray Generation System Based on Laser Compton Scattering | 1031 |
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Funding: This work is supported by MECSST High Tech Research Center Project No. 707 and JSPS (B) (2) 18340079. At Waseda University, we have succeeded in generating soft X-rays based on laser Compton scattering. The energies are within "Water Window" part (250~500eV) where the X-ray absorption coefficient of water is much less than that of constituent elements of living body such as carbon, hydrogen and nitrogen. For this reason, it is expected to apply to a bio-microscope with which we can observe living cells without dehydration. To improve the generation system, we remodeled our collision chamber and adopted 3-pass flash lamp amplifier system. With these modifications, we achieved high S/N ratio. The photon number detected by MCP was 278/pulse, tenfold increase of that in last year. Moreover, we succeeded in generating soft X-rays stably for more than 10 hours. Now we are planning to measure two-dimensional distribution of the X-rays by CCD. In this conference, experimental results and future plans will be reported. |
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| TUPMN050 | Development of Pulsed-Laser Super-Cavity for Compact X-Ray Source Based on Laser-Compton Scattering | 1034 |
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| A compact and high quality x-ray source is required from various field, such as medical diagnosis, drug manifacturing and biological sciences. Laser-Compton based x-ray source that consist of a compact electron storage ring and a pulsed-laser super-cavity is one of the solutions of compact x-ray source. Pulsed-laser super-cavity has been developed for a compact high brightness x-ray sources at KEK-ATF. The pulsed-laser super-cavity increases the laser power and stably makes small laser beam size at the collision point with the electron beam. Recently, 357MHz mode-locked Nd:VAN laser pulses can be stacked stably in a 420mm long Fabry-Perot cavity with 1'000 enhancement in our R&D. Therefore, we have planned a compact hard x-ray sources using 50MeV multi-bunch electrons and a pulse stacking technology with 42cm Fabry-Perot cavity. (LUCX Project at KEK) The photon flux is multiplied with the number of bunches by using multi-bunch beam and super-cavity. Development of the super-cavity and present result of LUCX will be presented at the conference. | ||
| TUPMN051 | Development of Photocathode RF Gun and Laser System for Multi-collision Laser Compton Scattering | 1037 |
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| A compact soft and hard X-ray source via laser Compton scattering is required for biological, medical and industrial science because it has many benefits about generated X-rays such as short pulse, quasi-monochromatic, energy tunability and good directivity. Our X-ray source is conventionally the single collision system between an electron pulse and a laser pulse. To increase X-ray yield, we have developed a multi-collision system with a multi-bunch electron beam and a laser optical cavity. The multi-bunch beam will be generated from a Cs-Te photocathode rf gun sytem using a multi-pulse UV laser. The laser optical cavity will be built like the regenerative amplification including a collision point between the electron pulse and the laser pulse to enhance the laser peak power per 1 collision on laser Compton scattering. In this conference, we will describe the results of preliminary experiments for the multi-collision system and future plans. | ||
| TUPMN052 | Completion of the Australian Synchrotron Storage Ring RF System Commissioning | 1040 |
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| The installation and commissioning of the Australian Synchrotron Storage Ring RF System (SR RF System) was completed. SR RF System consists of four sets of 500MHz 150kW-CW klystron and 750kV normal conducting cavity. After the cavity aging, the RF System achieved 48 hours continuous operation in November 2006. The paper will present the design and commissioning results. | ||
| TUPMN053 | Status of the Photocathode RF Gun at Tsinghua University | 1043 |
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The photocathode RF gun at Tsinghua University was built to develop electron source for the Thomson Scattering X-ray source. The main goal is to produce minimum transverse emittance beams with short bunch length at medium charge (~1nC). It includes a 1.6 cell S-band BNL/KEK/SHI type cavity, a solenoid for space charge compensation, a laser system to generate UV light, and different diagnostics tools. In this paper, it will include measurements of the dark current, the charge and quantum efficiency, momentum, transverse electron beam profiles at different locations and the transverse emittance.
This work was supported by the Chinese National Foundation of Natural Sciences under Contract no. 10645002. |
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| TUPMN054 | Design of a Source to Supply Ultra-fast Electron and X-Ray Pulses | 1046 |
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| In this paper we report the preliminary design and considerations on a multi-discipline ultra-fast source, which is capable of providing the user community with femtosecond electron bunch and light pulses with the wavelength ranging from IR to X-ray. The facility is based on photocathode RF gun driven by a Ti:Sapphire laser system. The low emittance subpicosecond electron bunch at the gun exit can be used in femtosecond electron diffraction setup to visualize the ultrafast structural dynamics. After acceleration and compression, the electron beam with the energy of 50 MeV is further used to provide high peak brightness X-ray by inverse Compton scattering with TW laser. We also consider the possibility and reliability of storing the electron beam in a compact storage ring and the laser pulse in a super-cavity. Operating in this scheme may increase the average flux of the X-ray photons by orders of magnitude. | ||
| TUPMN055 | First Principle Measurements of Thermal Emittance for Copper and Magnesium | 1049 |
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Funding: This work was supported by the Chinese National Foundation of Natural Sciences under Contract no. 10645002.
There are growing interests in generation, preservation and applications of high brightness electron beam. With the rapid development in the techniques for emittance compensation and laser shaping, we are approaching the limit-the uncorrelated thermal emittance. In this paper, we report the measurements of thermal emittance for Cu and Mg. The measurement is conducted in a field-free region. The energy spectrum and angular distribution of the electrons are measured immediately after its emission and further used to reconstruct the initial phase space and the corresponding thermal emittance. We also show how cathode surface roughness* and laser incidence angle as well as its polarization state** affect the quantum efficiency and thermal emittance.
*X. Z. He, High energy physics and nuclear physics,28(2004)1007.**Dao Xiang,et al, NIM A,562(2006)48. |
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| TUPMN056 | MEASUREMENTS OF LASER TEMPORAL PROFILE AND POLARIZATION-DEPENDENT QUANTUM EFFICIENCY | 1052 |
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Funding: The work was supported by the Program for New Century Excellent Talents in University and the National Natural Science Foundation of China (No.10645002） The ultrashort ultraviolet (UV) laser system and the optical transport line for driving the photocathode RF gun at Accelerator Laboratory of Tsinghua University are introduced in the article. Temporal profile of the UV pulse was measured by non-colinear difference frequency generation (DFG) between the UV pulse itself and the jitter-free residual IR laser pulse after third harmonic generation (THG) process. Experiments to measure the dependence of quantum efficiency (QE) on laser polarization state are also performed. Results show that in our case the ratio of QE between p- and s- polarization is more than 2.6. |
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| TUPMN057 | Design and Tuning of NSRL Undulator UD-1 | 1055 |
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| The design, construction, and tuning of the first undulator UD-1 in NSRL are described. The magnetic field design and requirement are given. The results of the magnet blocks measurement and the magnetic field tuning by interchanging magnet blocks are presented. | ||
| TUPMN058 | The Operation Status of HLS (Hefei Light Source) | 1058 |
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| National Synchrotron Radiation Lab, University of Science and Technology of China, P. R.China HLS(Hefei Light Source) is a dedicated synchrotron radiation research facility, spectrally strongest in Vacuum Ultra Violet and Soft X-ray. Designed and constructed in 1980's, accepted to regular service in 1991. From 1999 to 2004, the National Synchrotron Radiation Lab carried out its Phase II Project, in which quite a few sub-systems of HLS storage ring were upgraded and 8 new beamline were constructed. After the project, the performance of HLS is improved considerably. In this paper, the operation status and performance of storage ring in recent years were presented. With some measures, the operation beam intensity is about 300mA, beam lifetime is higher than before, orbit stability is met requirement of users, and the capability to provide synchrotron radiation exceeds the design value. | ||
| TUPMN059 | The Nonlinear Effects of Fringe Fields in HLS | 1061 |
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| As a small low energy electron storage ring, the fringe field effects on linear and nonlinear properties maybe can not be ignored. In this paper, the fringe field of dipole magnets and quadrupole magnets on linear optics parameters and nonlinear driving terms of general purpose operation mode in HLS storage ring were analyzed and calculated. The results showed that, for GPLS mode, the fringe field of dipole and quadrupole is the main source of tune shift with amplitude. The fringe field of dipole contributes non-ignorable part to vertical chromaticity. Similar behavour is also displayed in non linear driving terms. | ||
| TUPMN060 | A Low Emittance Lattice Design for HLS Storage Ring | 1064 |
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| Lower beam emittance is the most effective measure to higher brilliance of light source. To enhance performance of HLS ring, a new low emittance lattice was studied and introduced in this paper. The scale of new lattice is designed according to the current ground settlement of HLS ring, but the focusing structure and mangets were changed. The new designed lattice has two operation mode, low emittance mode and low momentum compaction mode. In this paper, the linear lattice function and dynamic aperutre of the new designed lattice was briefly introduced. Caculation results showed that, after upgrade, the brilliance of HLS storage ring can approach the level of third order light source. | ||
| TUPMN061 | An Upgrade Proposal of Injection Bump System for HLS | 1067 |
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| The current injection bump system of Hefei Light Source was designed eight years ago, and operated five years ago. In this paper, the advantages and shortcomings of current bump system were analyzed, and reasonalbe design objective was summed up. According to new design goal, a new physical design of bump system for HLS ring was completed. The acceptance of injected beam and perturbation on stored beam were analyzed. At same time, the ELEGANT software was used to simulate the injection process under new designed bump system. The results showed that, with new designed bump system, the injection rate would be higher than 90%, and the perturbation on orbit of stored beam would be small enough. | ||
| TUPMN064 | Experimental Approaches for the Beam Dynamics Study in the PC RF Gun at the PAL | 1070 |
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Funding: This work is supported in parts by the Center for High Energy Physics at the KNU and the Grant No. R01-2006-000-11309-0 from the Basic Research Program of the Korea Science and Engineering Foundation.
A high-brightness electron beam is emitted from a photo-cathode (PC) RF gun for use in the FIR (Far Infrared) facility being built at the Pohang Accelerator Laboratory (PAL). The beam dynamics study for the PAL XFEL injector is essencial to generate low emittance electron beam from the PC RF gun. The XFEL injector requires 1 nC beam with short bunch length and low emittance. This conditions are simulated with PARMELA code and then are realized on experimental conditions. The experimental conditions for the XFEL injector are measured with beam diagnostic devices such as ICT and Faraday cup for charge measurement, a spectrometer for beam energy measurement. In this article, we present the experimental approaches of the beam dynamics study for the XFEL injector.
wpjho@postech.ac.kr (Jangho Park) |
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| TUPMN066 | Status of the ALBA Project | 1073 |
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| The construction of ALBA, the 3 GeV third generation Synchrotron Light Source near Barcelona (Spain) is proceeding according to schedule. The works for the building started in June 2006 and access to the building for installation of the 100 MeV Linac is expected at the end of 2007. Most of the machine components are already under construction and some have already been delivered. This report will concentrate on recent design developments, component choices and current status. Also the results on the first prototypes will be discussed. Other papers at this conference deal with accelerator physics issues and low level RF. | ||
| TUPMN068 | Modelling of Gradient Bending Magnets for the Beam Dynamics Studies at ALBA | 1076 |
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| The performance of the ALBA light source will be strongly determined by the quality of the bending magnet. In the ALBA case, most of the vertical focusing takes place in the combined function bending magnet, and the contribution of the edge focusing is required to obtain a stable working point. Experience from other modern light sources using combined function magnets (CLS, ASP, Spear-III) shows that the usual hard model is not sufficient for an accurate modelling of the machine. In this paper, we review the methods to model the effect of the bending magnet, including fringe fields, and how to obtain a good model from the 3D magnetic model. | ||
| TUPMN070 | Magnet Block Arrangements for the Apple-II Elliptically Polarized Undulator | 1079 |
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| The good field region (magnetic field roll-off) of the horizontal and vertical field distribution in the elliptically polarized undulator (EPU) of the APPLE II structure is too short. Meanwhile, the strong force variation will be created between the magnet arrays on different phase. Hence, a magnet block was magnetized with an tilt angle has been studied to enlarge the good field region and a different arrangement of magnet block module is used to reduce the force variation. In addition, the pure and hybrid structure of the EPU with different end pole design has been studied. This study will obtain a small variation of the first and second field integral on different gap and phase. This work will report the scheme of the magnet block arrangement and the end pole design for the APPLE II elliptically polarized undulator. | ||
| TUPMN071 | Planning of Insertion Devices for 3 GeV Taiwan Photon Source | 1082 |
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| The Taiwan Photon Source (TPS) has 24 straight sections (10.9 m x6,5.7 m x18). It has at least three long straight and 18 medium straight for installing insertion devices. Most of the insertion devices are the in-vacuum undulator and produce intense X-rays with a brilliance of up to 1x1020 photons/s/mr2/mm2/0.1%bw. However, the cryogenic permanent magnet undulator with a periodic length of 1.8 cm (CU1.8) will be developed to provide an energy over 20 keV. One or two types of undulators can be installed in the long straight section to provide low photon energy or enable experiments to be conducted in situ in a single beam line. Meanwhile, some elliptically polarized undulators (APPLE II structure) are planned to provide circular and any linear polarization light. One or two superconducting wigglers with a field strength of 3.5 T will be used to yield the photons with energies of over 25 keV. A study project of superconducting undulator is for the energies of 2.5 - 25 keV. This work will report the design philosophy for the insertion devices and what kinds of insertion devices will be operated at TPS. | ||
| TUPMN072 | Current Status of Lattice Design and Accelerator Physics Issues of the 3 GeV Taiwan Synchrotron Light Source | 1085 |
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| In the past years, we have been conducting a design work for a synchrotron light facility with low emittance storage ring in the intermediate energy range in NSRRC. A number of design options with different lattice structure types, circumferences, etc., are compared. We present one design case with 24-cell DBA structure and 486 m circumference. The associated accelerator physics issues are discussed. | ||
| TUPMN073 | First Operation of a Thermionic Cathode RF Gun at NSRRC | 1088 |
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| An injector system that based on rf gun technology is being constructed at NSRRC. This will be a 100 MeV beam injector that consists of an rf linac with a thermionic cathode rf gun as electron source. The superior performance and special configuration of the thermionic rf gun system made it an attractive option as a reliable pre-injector booster synchrotron. In cooperation with an alpha-magnet as low energy bunch compressor, ultra-fast electron beam pulses as short as 100 fs can be generated from the thermionic cathode rf gun for generation of intense coherent short wavelength radiations, production of femto-second electron and wavelength tunable ultra-fast X-ray pulses. First operation of the thermionic rf gun will be presented. | ||
| TUPMN074 | Improvements to the Injection Efficiency at the Taiwan Light Source | 1091 |
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| Taiwan light source started the 200 mA top-up operation in October 2005, and the stored beam current was subsequently ramped up to 300 mA top-up operation. In the early phase of top-up operation, the injection efficiency had large variation at different machine condition. We have developed the procedures to maintain the injection efficiency. These optimization procedures will be activated whenever the injection efficiency degrades during the top-up operation of TLS. | ||
| TUPMN075 | BEAM LIFETIME ESTIMATION FOR TAIWAN 3GEV SYNCHROTRON LIGHT SOURCE | 1094 |
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| The demanding design features of Taiwan Photon Source (TPS), low emittance and small gap undulator vacuum vessels, cause Touschek scattering and gas scattering to play a major limitation role for beam lifetime. We calculate the Touschek lifetime based on the tracking procedure determining energy acceptance. The nonlinear synchrotron oscillation due to large second-order momentum compaction factor is included in the energy acceptance calculations. Small vertical ID gaps are imposed in the tracking procedure. Besides, the gas scattering lifetime is estimated with varying gas pressure. The possible improvement solutions for lifetime will be addressed. | ||
| TUPMN076 | The Fabrication and Characterization of an S-band RF-gun Cavity | 1097 |
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| A single cell rf-gun cavity is designed and fabricated for the purpose of examining the feasibility of installing a thermionic rf-gun at NSRRC instead of a photocathode rf-gun considered previously. The operating frequency of the rf-gun cavity is set at 2856 MHz in order to utilize the available XK-5 klystron and linac. The fabricated parts of the OFHC copper cavity are brazed together in-house and then the cavity is characterized by rf measurement. It shows that the cavity gives very good character in terms of high quality factor, relaxed tuning range, adequate coupling coefficient, and reasonable reproducibility. The properties of the cavity are further explored by measuring the field profile and its response to an rf pulse in which the filling time is deduced. The measurement results of this brazed cavity are described and summarized in this report. | ||
| TUPMN082 | Injector Design for the 4GLS High Average Current Loop | 1100 |
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| The proposed 4th Generation Light Source (4GLS) consists of three electron branches. We present the design of the injector for the High Average Current Loop which feeds spontaneous light sources and a Vacuum Ultra-Violet FEL. The injector aims to provide 77 pC bunches at a repetition rate of up to 1.3 GHz which corresponds to an average current of 100 mA. It consists of a 500 kV GaAs based DC photocathode electron gun equipped with a photocathode preparation facility, followed by a normal-conducting buncher cavity and a 10 MeV superconducting RF booster. Simulations are presented which show the injector provides a beam with a normalised rms transverse emittance of less than 3 π·mm·mrad and a bunch length of about 2 ps. | ||
| TUPMN083 | Electron Beam Dynamics in 4GLS | 1103 |
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Funding: Some of the work reported in this paper is supported by the EuroFEL programme. Studies of the electron beam dynamics for the 4GLS design are presented. 4GLS will provide three different electron bunch trains to a variety of user synchrotron sources. The 1 kHz XUV-FEL and 100 mA High Average Current branches share a common 540 MeV linac, whilst the 13 MHz IR-FEL must be well-synchronised to them. An overview of the injector designs, electron transport, and energy recovery is given, including ongoing studies of coherent synchrotron radiation, beam break-up and wakefields. This work is being pursued for the forthcoming Technical Design Report due in 2008. |
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| TUPMN084 | The Status of the Daresbury Energy Recovery Linac Prototype | 1106 |
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| As part of the UK's R&D programme to develop an advanced energy recovery linac-based light source (4GLS); a 35 MeV technology demonstrator called the Energy Recovery Linac Prototype (ERLP) has been constructed. It is based on a combination of a DC photocathode electron gun, a superconducting injector linac and main linac operating in energy recovery mode, driving an IR-FEL. The priorities for this machine are to gain experience of operating a photoinjector gun and superconducting linacs; to produce and maintain high-brightness electron beams; achieving energy recovery from an FEL-disrupted beam and studying important synchronisation issues. The current status of this project is presented, including construction and commissioning progress, including plans for the future exploitation of this scientific and technical R&D facility. | ||
| TUPMN085 | The Commissioning of the Diamond Storage Ring | 1109 |
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| The Diamond Light Source opened for user operation at the end January 2007. The storage ring was successfully commissioned at 3 GeV in three months by the end of December 2006. An intensive Accelerator Physics program allowed the design emittance of 2.7 nm with 150 mA stored beam to be reached as well as the commissioning of the first seven insertion devices. We describe here the results of the measurements performed to characterise accelerator optics, to bring the insertion device in operation and a first analysis of orbit stability and collective instabilities, as well as the status and plans for fast orbit feedback, multi-bunch feedback and top-up operation. | ||
| TUPMN086 | Operation of the Diamond Light Source Injector | 1112 |
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| The Diamond Light source injector consists of a 100 MeV pre-injector linac and a 3 GeV full energy booster. The injection system has been reliably providing beam to the storage ring since September 2006 in both multibunch and single bunch mode, at 5 Hz repetition rate. All user operation at present is carried out in multibunch mode, with an injection efficiency up to 95%. Single bunch and hybrid modes are being developed now for users later this year. Differences in operation between multibunch and single bunch mode are largely restricted to the linac, although a small correction in booster sextupole ramp is needed for single bunch operation. Single bunch purity has been measured in the storage ring to be greater than 99.9%. The timing system can be controlled to allow a wide range of filling patterns, including complete ring fill in both single and multibunch mode, and hybrid fills with individual single bunches placed in gaps between continuous bunch trains. Top-up operation is envisaged for user operation in the future, and trials are underway to ensure safe and efficient running in this mode. | ||
| TUPMN087 | Electron Beam Dynamics Studies During Commissioning of the Diamond Storage Ring | 1115 |
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| The Diamond Light Source is the new medium energy 3rd generation light source located at the Harwell Science and Innovation Campus in the UK. The storage ring was successfully commissioned at full energy during the period Sept. to Dec. 2006, and is now delivering synchrotron light to users. During the commissioning period, operation of the storage ring at the design specifications was established in terms of closed orbit distortion, linear optics, coupling correction and emittance. In this report we provide details of these studies as well as more recent investigations of non-linear beam dynamics. | ||
| TUPMN088 | Commissioning and Investigation of Beam Dynamics of Phase I Insertion Devices at Diamond | 1118 |
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| Diamond is a 3 GeV low emittance third generation light source recently commissioned in Oxfordshire, UK. During Phase I of the project, seven insertion devices (IDs) have been installed and commissioned: these include 5 in-vacuum permanent magnet undulators, a variable polarization APPLE-II helical device and a superconducting wiggler. We present our experiences commissioning these devices and the results of the investigations of their effects on beam dynamics, including orbit distortion, linear tune shifts, beta-beating and beam lifetime. Alpha-matching with local and global tune compensations, as well as the LOCO algorithm, have been used to compensate the linear optic perturbations. The results are discussed and compared with theoretical predictions. Injection with IDs in operation has also been investigated in view of future top-up operation. | ||
| TUPMN089 | Configuration, Optics, and Performance of a 7-GeV Energy Recovery Linac Upgrade for the Advanced Photon Source | 1121 |
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Funding: Work supported by the U. S. Department of Energy, Office of Science, Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. The Advanced Photon Source (APS) is a 7-GeV storage ring light source that has been in operation for over a decade. In order to make revolutionary improvements in the performance of the existing APS ring, we are exploring the addition of a 7-GeV energy recovery linac (ERL) to the APS complex. In this paper, we show the possible configuration of such a system, taking into account details of the APS site and the requirement that stored beam capability be preserved. We exhibit a possible configuration for the single-pass, 7-GeV linac. We discuss optical solutions for transport from 10 MeV to 7 GeV and back, including a large turn-around arc that would support 48 additional user beamlines. Tracking results are shown that include incoherent and coherent synchrotron radiation, resulting in predictions of the beamline performance. |
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| TUPMN090 | Evaluation of the Possibility of Using Damping Wigglers in the Advanced Photon Source | 1124 |
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Funding: Work supported by the U. S. Department of Energy, Office of Science, Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. The Advanced Photon Source (APS) is a 7-GeV storage ring light source that has been in operation for over a decade. Over time, the performance of the APS has been increased by reduction of the emittance from 8 nm to 3.1 nm and by the use of top-up mode. We continue to explore options for improving the performance further. This paper discusses the possible improvements in emittance that could result from the use of damping wigglers. We also discuss rf and space requirements. |
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| TUPMN091 | Planned Use of Pulsed Crab Cavities for Short X-ray Pulse Generation at the Advanced Photon Source | 1127 |
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Funding: Work supported by the U. S. Department of Energy, Office of Science, Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
In recent years, we have explored application to the Advanced Photon Source (APS) of Zholents'* crab-cavity-based scheme for production of short x-ray pulses. Work concentrated on using superconducting (SC) cavities in order to have a continuous stream of crabbed bunches and flexibility of operating modes. The challenges of the SC approach are related to the size, cost, and development time of the cavities and associated systems. A good case can be made for a pulsed system** using room-temperature cavities. APS has elected to pursue such a system in the near term, with the SC-based system planned for a later date. This paper describes the motivation for the pulsed system and gives an overview of the planned implementation and issues. Among these are overall configuration options and constraints, cavity design options, frequency choice, cavity design challenges, tolerances, instability issues, and diagnostics plans.
*A. Zholents et al., NIM A 425, 385 (1999).**P. Anfinrud, private communication. |
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| TUPMN092 | Phasing of Two Undulators with Different K Values at the Advanced Photon Source | 1130 |
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Funding: Work supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. Two full-length 2.4-m-long undulators, with period lengths 2.3 cm and 2.7 cm, were recently installed in tandem in the 5.6-m-long straight on the storage ring in sector 14. One part of the user research program requires that both undulators be tuned to 12.0 keV and the x-ray intensity maximized. The total intensity is sensitive to the phasing between the undulators, so the distance between the devices must be optimized and the ends tuned appropriately. Because of the different period lengths, the gaps and K values of the undulators will be different: 10.6-mm gap and a K value of 1.17 for the shorter-period device and 15.7-mm gap and a K value of 0.93 for the longer-period device. A special shield was designed and installed between the devices to eliminate interference. Results of magnetic measurements, tuning, and computer simulations of the spectral performance are presented. |
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| TUPMN093 | A Kilohertz Picosecond X-Ray Pulse Generation Scheme | 1133 |
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| The duration of the x-ray pulse generated at a synchrotron light source is typically tens of picoseconds. Shorter pulses are highly desired by the users. In electron storage rings, the vertical beam size is usually orders of magnitude less than the bunch length due to radiation damping; therefore, a shorter pulse can be obtained by slitting the vertically tilted bunch. Zholents proposed tilting the bunch using rf deflection. We found that tilted bunches can also be generated by a dipole magnet kick. A vertical tilt is developed after the kick in the presence of non-zero chromaticity. The tilt was successfully observed and a 4.2-ps pulse was obtained fom a 27-ps electron bunch at the Advanced Photon Source. Based on this principle we propose a short-pulse generation scheme that produces picosecond x-ray pulses at a repetition rate of 1~2 kHz, which can be used for pump-probe experiments. The tilt phenomenon can also be utilized for machine parameter measurement. | ||
| TUPMN094 | Development of a Model Superconducting Helical Undulator for the ILC Positron Source | 1136 |
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Funding: Work supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. Model superconducting helical undulators are under development for the proposed International Linear Collider (ILC) positron source. The undulator requires high-permeability steel poles and superconducting coils to meet the ILC parameters. A fabrication method for steel poles on a nonmagnetic beam chamber was developed. A model undulator with a period length of 14 mm and Nb3Sn coils was fabricated. Both ends of the model were designed to provide for continuous winding of a single conductor with 39 turns per helix. A 10-mm-period model was designed and is in the fabrication process. The 14-mm-period model may be used in the development of a cryogenic magnetic measurement system. Details of the fabrication and test results will be presented. |
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| TUPMN096 | New Lattice Design for APS Storage Ring with Potential Tri-fold Increase of the Number of Insertion Devices | 1139 |
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Funding: Work supported by the U. S. Department of Energy, Office of Science, Basic Energy Sciences, under Contract No. DE-AC02-06CH11357 APS has recently held a round of discussions on upgrade options for the APS storage ring. Several options were discussed that included both storage ring and energy-recovery linac options. Here we present a storage ring lattice that fits into the APS tunnel and has a number of significant improvements over the existing storage ring. The present APS lattice has 40-fold symmetry with each sector having one 5-m-long straight section for insertion device (ID) placement. Each sector also provides one beamline for radiation from the bending magnet. The upgrade lattice preserves locations of the existing insertion devices but provides for increased ID straight section length to accommodate 8-m-long insertion devices. This lattice also decreases emittance by a factor of two down to 1.6 nm rad. And last but not least, it provides two additional 2.1-m-long ID straight sections per sector with one of these straight sections being parallel to the existing bending magnet beamline. We also present dynamic aperture optimization, lifetime calculations, and other nonlinear-dynamics-related simulations. |
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| TUPMN097 | A Possibility for Using an APPLE Undulator to Generate a Photon Beam with Transverse Optical Modes | 1142 |
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Funding: Work supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract DE-AC02-06CH11357.
Photons that carry orbital angular momentum are of great interest to the optics and laser communities*. This exotic property of photon beams was recently demonstrated in the x-ray regime** and may be useful to probe angular momentum in matter***. However, by comparison to the visible light regime, it is difficult to fabricate efficient achromatic optics to generate these optical modes in x-rays. In spite of these inconveniences, there has been no investigation of the possibility of using a synchrotron light source to directly generate an x-ray beam with transverse optical modes. In this paper, we investigate use of an APPLE-type undulator for generating Laguerre-Gaussian (LG) and Hermite-Gaussian (HG) mode beams. We find that the second harmonic radiation in the circular mode corresponds to an LG beam with l=1, and the second harmonic in the linear mode corresponds to an HG beam with l=1. The combination of an APPLE undulator and conventional monochromator optics may provide an opportunity for a new type of experimental research in the synchrotron radiation community. Detailed discussion will be presented in the conference. We thank C. Quitmann for insightful comments.
* M. Padgett, J. Courtial, L. Allen, Physics Today, p. 35, May, 2004.** A. G. Peele et al., Optics Letters, 27, 1752 (2002).*** M. VanVeenendaal and I. McNulty, Phys. Rev. Lett., submitted. |
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| TUPMN099 | An Energy Recovery Linac Upgrade for the Advanced Photon Source Located in the Storage Ring Infield | 1145 |
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Funding: Work supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. In the recent past, the Advanced Photon Source (APS) was asked by the U. S. Department of Energy to explore a revolutionary upgrade based on emerging energy recovery linac (ERL) technology. In an ERL, the energy of the 7-GeV, 100-mA beam is recovered after the beam passes through user beamlines by decelerating the beam back through the same superconducting linac cavities that accelerated it. The main constraint on this upgrade is that the existing APS beamlines not be disturbed. This requires that the APS storage ring be used as a single-pass transport line in the overall ERL beamline layout. A natural place to locate the ERL is inside the existing APS storage ring ‘‘infield'' area, which has unoccupied space south of the existing APS injector complex. Other important constraints include minimal disturbance of existing building structures and injector beamlines. The existing injector complex would be preserved so that existing operation can be continued through and even possibly beyond ERL commissioning. In this paper, we describe a layout that satisfies these constraints. We also estimate the amount of emittance increase the beam will experience before ring injection. |
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| TUPMN100 | LCLS Undulator Production | 1148 |
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Funding: Work supported by the U. S. Dept. of Energy, under contract numbers DE-AC02-06CH11357 and DE AC03-76SF00515.
Design and construction of the undulators for the Linac Coherent Light Source (LCLS) is the responsibility of Argonne National Laboratory. A prototype undulator* was constructed in-house and was extensively tested. The device was tunable to well within the LCLS requirements and was stable over a period of several years. Experience constructing the prototype undulator led us to conclude that with appropriate engineering design and detailed assembly procedures, precision undulators can be constructed by qualified vendors without previous undulator-construction experience. Our detailed technological knowledge and experience were transferred to the successful bidders who have produced outstanding undulators. Our production concept for the 40 3.4 m long, fixed-gap, planar-hybrid undulators with a 30 mm period is presented. Manufacturing, quality assurance, and acceptance testing details are also presented.
*LCLS Prototype Undulator Report, Argonne National Laboratory Report ANL/APS/TB-48, January 2004, R. Dejus, Editor. |
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| TUPMN101 | A Study of the Minimum Wall Thickness for an Extruded Aluminum Vacuum Chamber | 1151 |
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Funding: Work at Argonne National Laboratory is supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences under contract # DE-Ac02-06CH11357.
Multiple vacuum chambers for the insertion devices with 1-mm wall thickness were developed at Argonne for the APS and many other synchrotron radiation facilities.* Using the extrusion for the insertion device vacuum chamber (ID VC) for the DESY FEL project with a 9.5-mm inner diameter, we decreased the wall thickness to 0.6, 0.5, and 0.4 mm to test the vacuum integrity for a thin wall in these extrusions. A special ultrasonic transducer with a 1/8" diameter was required to do the job. Also some additional short samples, machined exactly as the experimental piece, were used to verify wall thickness mechanically. Experimental setup and test results are presented.
* Trakhtenberg E., Wiemerslage G., Den Hartog P. "New insertion device vacuum chambers at the Advanced Photon Source", PAC 2003 Particle Accelerator Physics Conference; Portland, OR. |
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| TUPMN102 | Electromagnetic Design of the RF Cavity Beam Position Monitor for the LCLS | 1153 |
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Funding: Work supported by the U. S. Department of Energy under Contract Nos DE-AC02-06CH11357 and DE-AC03-76SF00515. A high-resolution X-band cavity beam position monitor (BPM) has been developed for the LCLS in order to achieve micron-level accuracy of the beam position using a dipole mode cavity and a monopole mode reference cavity. The rf properties of the BPM will be discussed in this paper including output power, tuning, and issues of manufacturing. In addition, methods will be presented for improving the isolation of the output ports to differentiate between horizontal/vertical beam motion and to reject extraneous modes from affecting the output signal. The predicted simulation results will be compared to data collected from low-power experimental tests. |
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| TUPMN104 | A Design Study for Photon Diagnostics for the APS Storage Ring Short-Pulse X-ray Source | 1156 |
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Funding: Work supported by U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
A short x-ray pulse source based on the crab cavity scheme proposed by Zholents* is being developed at the Advanced Photon Source (APS). Photon diagnostics that visualizes the electron bunches with transverse momentum chirp and verifies the performance of the short x-ray pulse is required. We present a design study for the imaging diagnostics inside and outside of the crab cavity zone, utilizing both x-ray and visible synchrotron radiation. Several design options of monochromatic and polychromatic x-ray optics will be explored for their compatibility with the short-pulse source. The diagnostics outside of the crab cavity zone will be used to map out stable operation parameters of the storage ring with crab cavities, and to perform single-bunch single-pass imaging of the chirped bunch, which facilitates the tuning of the crab cavity rf phase and amplitude so the performance of the short pulse source can be optimized while other users around the ring will not be disturbed.
* A. Zholents et al., NIM A 425, 385 (1999). |
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| TUPMN106 | MCP based Electron Gun | 1159 |
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| We propose to use micro-channel plate (MCP) as a cathode for electron guns. We suggest possible arrangement of MCP in DC and RF guns and discuss feasibility and possible advantages of the method. | ||
| TUPMN107 | A Proposed Multipole Wiggler for CAMD | 1161 |
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| It is proposed to replace the 7 Tesla wavelength shifter, which has been operating in CAMD since 1998, with a superconducting Multi Pole Wiggler (MPW). This will have 11 main poles with peak fields of 7.5 Tesla and will be accommodated in a cryo-cooled cryostat whose overall length will be 2.5 m. It will be necessary to modify the storage ring lattice parameters in order to inject into the reduced 20 mm vertical aperture of this MPW. The results are presented of tests which have been made of several different lattice configurations which have low vertical beta at the proposed location of the MPW. | ||
| TUPMN108 | Particle-in-Cell Calculations of the Electron Cloud in the ILC Positron Damping Ring Wigglers | 1164 |
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Funding: This work was supported by the Office of High Energy Physics of the U. S. Department of Energy under contract number No. DE-AC02-05CH11231. Due to copious synchrotron radiation from the beam, electron cloud effects are predicted to be important in the wiggler sections of the ILC positron damping ring. In this area of the ring, the physics is inherently 3D. Moreover, a self-consistent calculation of the physics of the electron cloud/beam system is necessary for examining such phenomena as emittance growth in the beam. We present the first calculations of this system with the self-consistent 3D particle-in-cell code WARP/POSINST. The code includes self-consistent space charge for both species, mesh refinement, and detailed models of primary and secondary electron production. Interaction with electrons is assumed to occur only in the wigglers in this model– the beam is moved using maps between wiggler sections. |
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| TUPMN109 | A High Repetition Rate VUV-Soft X-Ray FEL Concept | 1167 |
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Funding: This work was supported by the Director, Office of Science, High Energy Physics, U. S. Department of Energy under Contract No. DE-AC02-05CH11231. The FEL process increases radiation flux by several orders of magnitude above existing incoherent sources, and offers the additional enhancements attainable by optical manipulations of the electron beam: control of the temporal duration and bandwidth of the coherent output, and wavelength; utilization of harmonics to attain shorter wavelengths; and precise synchronization of the x-ray pulse with laser systems. We describe an FEL facility concept based on a high repetition rate RF photocathode gun, that would allow simultaneous operation of multiple independent FELs, each producing high average brightness, tunable over the soft x-ray-VUV range, and each with individual performance characteristics determined by the configuration of the FEL SASE, enhanced-SASE (ESASE), seeded, self-seeded, harmonic generation, and other configurations making use of optical manipulations of the electron beam may be employed, providing a wide range of photon beam properties to meet varied user demands. FELs would be tailored to specific experimental needs, including production of ultrafast pulses even into the attosecond domain, and high temporal coherence (i.e. high resolving power) beams. |
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| TUPMN111 | A Low Emittance Lattice for the Advanced Light Source | 1170 |
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Funding: Work supported by the U. S. Department of Energy under Contract No. DE-AC03-76SF00098 The possibility exists of achieving significantly lower emittances in an electron storage ring by increasing its horizontal betatron tune. However, existing magnet locations and strengths in a given ring may be inadequate to implement such an operational mode. For example, the ALS storage ring could lower its emittance to one third of the current value by increasing the horizontal tune from 14.25 to 16.25. However, this would come with the cost of large chromaticities that could not be corrected with our existing sextupole magnets. We discuss such operational issues and possible options in this paper. |
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| TUPMN112 | ALS Top-off Simulation Studies for Radiation Safety | 1173 |
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Funding: Work supported by the U. S. Department of Energy under Contract No. DE-AC03-76SF00098 We plan to commission top-off injection at the Advanced Light Source in the near future. In order to guarantee radiation safety, we have been simulating the injection process to exclude the possibility of injected electrons traveling down the user's photon beam lines. As the final stage of our simulation study, we use photon beam line CAD drawings to define the beam line's aperture in the phase space which electrons must not enter. Then we virtually inject electrons from within these phase spaces backwards into the storage ring to prove that such electrons can never get back to the real injection point under any possible scenario. This paper summarizes such inverse tracking studies. |
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| TUPMN113 | A Plasma Channel Beam Conditioner for Free electron Lasers | 1176 |
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Funding: Work supported by the U. S. Department of Energy, Office of Basic Energy Sciences, under Contract No. DE-AC02-05CH11231. By "conditioning" an electron beam, through establishing a correlation between transverse action and energy within the beam, the performance of free electron lasers (FELs) can be dramatically improved. Under certain conditions, the FEL can perform as if the transverse emittances of the beam were substantially lower than the actual values. After a brief review of the benefits of beam conditioning, we present a method to generate this correlation through the use of a plasma channel. The strong transverse focusing produced by a dense plasma (near standard gas density) allows the optimal correlation to be achieved in a reasonable length channel, of order 1 m. This appears to be a convenient and practical method for achieving conditioned beams, especially in comparison with other methods which require either a long beamline or multiple passes through some type of ring. |
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| TUPMN114 | Simulation of the Microbunching Instability in Beam Delivery Systems for Free Electron Lasers | 1179 |
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| In this paper, we examine the growth of the microbunching instability in the chain of linac sections and bunch compressor chicanes used in the electron beam delivery system of a free electron laser. We compare the results of two sets of simulations, one conducted using a direct Vlasov solver, the other using a particle-in-cell code Impact-Z with the number of simulation macroparticles ranging up to 100 million. The comparison is focused on the values of uncorrelated (slice) energy spread at different points in the lattice. In particular, we discuss the interplay between physical and numerical noise in particle-based simulations, and assess the agreement between the simulation results and theoretical predictions. | ||
| TUPMN115 | Creating a Pseudo Single Bunch at the ALS | 1182 |
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Funding: This work was supported by U. S. Department of Energy under Contract No. DE-AC03-76SF00098. Typically storage ring light sources operate with the maximum number of bunches as possible with a gap for ion clearing. By evenly distributing the beam current the overall beam lifetime is maximized. The Advanced Light Source (ALS) has 2 nanoseconds between the bunches and typically operates with 276 bunches out of a possible 328. For experimenters doing timing experiment this bunch separation is too small and would prefer to see only one or two bunches in the ring. In order to provide more flexible operations and substantially increase the amount of operating time for time-of-flight experimenters, it is being proposed to kick one bunch on a different vertical closed orbit. By spatially separating the light from this bunch from the main bunch train in the beamline, one could potentially have single bunch operation all year round. By putting this bunch in the middle of the ion clearing gap the required bandwidth of the kicker magnets is reduced. Using one kicker magnet running at the ring repetition rate (1.5 MHz), this bunch could be permanently put on a different closed orbit. Using multiple kicker magnets, this bunch could be locally offset at an arbitrary frequency. |
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| TUPMN116 | Numerical Study of Coulomb Scattering Effects on Electron Beam from a Nano-tip | 1185 |
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Funding: This work was supported by the U. S. Department of Energy under Contract no. DE-AC02-05CH11231. Nano-tips with high acceleration gradient around the emission surface have been proposed to generate high brightness beams. However, due to the small size of the tip, the charge density near the tip is very high even for a small number of electrons. The Coulomb scattering near the tip can significantly degrade the beam quality and cause extra emittance growth and energy spread. In the paper, we present a numerical study of these effects using a direct relativistic N-body model. We found that emittance growth and energy spread, due to Coulomb scattering, can be significantly enhanced with respect to mean-field space-charge calculations in different parameter regimes. |
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| TUPMN117 | Exploring the Limits of the ALS Triple Bend Lattice | 1188 |
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Funding: Work supported by the U. S. Department of Energy under Contract No. DE-AC03-76SF00098 The triple bend achromat cell of the ALS has been shown to be very flexible and compact. It has been operated in a low emittance mode and a low momentum compaction mode. In fact the lattice can be operated in a large range of different stable modes. Until recently most of these recently discovered modes had not been explored or even known about. Many of these modes have potentially attractive features as compared with the present operational mode. In this paper we take a step back and look at the general stability limits of the lattice. We employ a technique we call GLASS that allows us to rapidly scan and find all possible stable modes and then characterize their associated properties. In this paper we illustrate how the GLASS technique gives a global and comprehensive vision of the capabilities of the lattice. |
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| TUPMN119 | Energy Recovery Transport Design for Peking University FEL | 1191 |
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Funding: supported by National 973 Projects and the U. S. Department of Energy Contract No. DE-AC05-06OR23177 A free-electron laser based on a superconducting linac is under construction in Peking University. To increase FEL output power, energy recovery is chosen as one of the most potential and popular ways. The design of a beam transport system for energy recovery is presented, which is suitable for the Peking University construction area. Especially, a chicane structure is chosen to change path length at ±20 degree and M56 in the arc is adjusted for fully bunch compression. |