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MOPCH071 | Optimization of Optics at 200 MeV KEK-ERL Test Facility for Suppression of Emittance Growth Induced by CSR | CSR, emittance, dipole, insertion-device | 190 | ||||
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Energy Recovery Linac (ERL) gets a lot of attention as a next period light source instrument. To produce high-brightness and short pulse synchrotoron lights, it is necessary to pass through high current and short bunch electron beams to the insertion part of ERL with keeping the low emittance and the low energy spread. However, it is challenging because Coherent Synchrotorn Radiation (CSR) generated at bending magnets is potential sources of the emittance growth which is enomous especially for high current, short bunch and a low energy beam. Therefore, it is benefit to a gradual bunch compression in the arc after accelerating the beam up to the full energy. The beam optics and lattice design of 200MeV ERL Test Facility is optimized to suppress the emittance growth caused by CSR at the arc section on two conditions, high-current mode (100mA, 1psec) and short bunch mode (0.1psec) similar to 5GeV ERL facility proposed by Cornell University.
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MOPCH091 | An Alternative Nonlinear Collimation System for the LHC | collimation, LHC, sextupole, optics | 246 | ||||
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The optics design of an alternative nonlinear collimation system for the LHC is presented. We discuss an optics scheme based on a single spoiler located in between a pair of skew sextupoles for betatron collimation. The nonlinear system allows opening up the collimator gaps and, thereby reduces the collimator impedance, which presently limits the LHC beam intensity. After placing secondary absorbers at optimum locations behind the spoiler, we analyze the beam losses and calculate the cleaning efficiency from tracking studies. The results are compared with those of the conventional linear collimation system.
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MOPCH174 | Optimization of the BCP Processing of Elliptical Nb SRF Cavities | simulation, LEFT, extraction, DESY | 469 | ||||
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Bulk niobium (Nb) electropolished SRF cavities performing at or above 35 MV/m is an aggressive goal recently put forth by the International Linear Collider (ILC) collaboration. Buffered chemical polishing (BCP) is still the most cost effective and least complex processing technique known today to optimize the surface properties of high gradient single crystal and relatively low gradient polycrystalline SRF cavities. BCP will be the preferred chemical process in the production of the nine-cell third harmonic 3.9 GHz cavities at Fermilab. The internal shape of these cavities will result in uneven material removal rates between iris and equator of the cells. We will describe a thermal-fluid finite element model adopted to simulate the etching process, and thus revealing the issues at hand. Experimental work, such as flow visualization tests performed to verify the simulation, will also be discussed. Finally we are presenting results obtained with a novel device, which allows to homogenize the flow pattern and to resolve the problem.
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MOPCH191 | Copper Heat Exchanger for the External Auxiliary Bus-bars Routing Line in the LHC Insertion Regions | LHC, CERN, cryogenics, quadrupole | 508 | ||||
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The corrector magnets and the main quadrupoles of the LHC dispersion suppressors are powered by a special superconducting line (called auxiliary bus-bars line N), external to the cold mass and housed in a 50 mm diameter stainless steel tube fixed to the cold mass. As the line is periodically connected to the cold mass, the same gaseous and liquid helium is used for cooling the magnets and the line. The final sub-cooling process (from 4.5 K down to 1.9 K) consists of the phase transformation from liquid to superfluid helium. It is slightly delayed with respect to the magnets. To accelerate the process, a special heat exchanger has been designed. Located in the middle of the dispersion suppressor portion of the line it consists in creating a local sink of heat extraction, providing two additional λ fronts that propagate in opposite directions towards the line extremities. Both the numerical model and the sub-cooling analysis are presented in the paper for different configurations of the line. Design, manufacturing and integration aspects of the heat exchanger are described. Finally, the results of the qualification tests and the expected performance of the line are given.
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MOPLS002 | The Study of the Machine-induced Background and its Applications at the LHC | background, LHC, shielding, CERN | 529 | ||||
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We present the recent advances in the analysis of the machine-induced background generation and formation at the LHC. Different aspects of the study of the machine background problem at the LHC are reviewed, including the background production at the different stages of the machine operation, the role and influence on the background from the collimators in the experimental insertions and the background shielding. The potential use of the machine background for the purposes of detector testing and alignment is also discussed.
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MOPLS003 | Tertiary Halo and Tertiary Background in the Low Luminosity Experimental Insertion IR8 of the LHC | background, shielding, LHC, simulation | 532 | ||||
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In our report we present the results for numerical simulation of tertiary halo and tertiary background in the LHC. We study the case of the proton losses in the betatron cleaning insertion IR7 with the subsequent tertiary halo generation in the downstream experimental insertion IR8. We analyze the formation of tertiary background in the experimental area of the IR8 and evaluate the performance of the machine-detector interface shielding with respect to this source of the background. The results obtained are compared with the previous estimates of the machine-induced background in the low luminosity insertions of the LHC, and the balance between different sources of the background is discussed.
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MOPLS008 | Beam Halo on the LHC TCDQ Diluter System and Thermal Load on the Downstream Superconducting Magnets | LHC, collimation, simulation, superconducting-magnet | 547 | ||||
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The moveable single-jawed graphite TCDQ diluter must be positioned very close to the circulating LHC beam in order to prevent damage to downstream components in the event of an unsynchronised beam abort. A two-jawed graphite TCS collimator forms part of the TCDQ system. The requirement to place the TCDQ and TCS jaws close to the beam means that the system can intercept a substantial beam halo load. Initial investigations indicated a worryingly high heat load on the Q4 coils. This paper presents the updated load cases, shielding and simulation geometry, and the results of simulations of the energy deposition in the TCDQ system and in the downstream superconducting Q4 magnet. The implications for the operation of the LHC are discussed.
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MOPLS011 | Investigations of the Parameter Space for the LHC Luminosity Upgrade | luminosity, LHC, quadrupole, separation-scheme | 556 | ||||
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Increasing the LHC luminosity by a factor of ten is a major challenge, not so much for the beam optics but certainly for the beam-beam long-range interactions and even more for the technology and layout: the quadrupole gradient, its physical aperture and tolerance to the energy deposition shall be significantly increased; its distance to the crossing point shall be reduced if the particle detectors can allow it. To help identifying consistent solutions in this multi-dimensional constrained space, a algorithmic model of an LHC insertion was prepared, based on the present LHC layout, i.e., "quadrupole first" and small crossing angle. The model deals with the layout, the beam optics, the beam-beam effect, the superconductor field margins and the peak heat deposition in the coils. The approach is simplified to allow a large gain in the design/computation time for optimization. First results have shown the need to use the Nb3Sn technology (or a material of equivalent performance) to reach the performance goal. In this paper, the model is refined to take into account the quench levels and temperature margins. The optimal insertions within the framework of this approach are identified.
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MOPLS070 | Numerical Calculations of Collimator Insertions | simulation, impedance, SLAC, CERN | 709 | ||||
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A series of collimator spoilers have been designed and manufactured for testing in the ESA wakefield tests. The purpose of the tests is a benchmarking exercise to assist with the understanding into the causes of wakefields due to spoiler profile and materials. Simulations of the spoiler designs have been used to understand the likely effects that would be observed with the beam tests. Simulations of these collimator insertions have been carried out in MAFIA and GDFIDL, and a comparison of the results completed. The wake potential has been measured, and the corresponding loss factor and kick factors have been calculated. The results from the simulations are discussed in this report.
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TUODFI01 | The Final Collimation System for the LHC | LHC, collimation, impedance, proton | 986 | ||||
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The LHC collimation system has been re-designed over the last three years in order to address the unprecedented challenges that are faced with the 360 MJ beams at 7 TeV. The layout of the LHC has now been fixed and a final approach for collimation and cleaning has been adopted. In total 132 collimator locations have been reserved in the two LHC rings and can be installed in a phased approach. Ninety collimators of five different types will be available for initial beam operation. The system has been fully optimized for avoiding quenches of super-conducting magnets during beam losses and for sufficient survival of beamline components against radioactive dose. The phased approach for LHC collimation is described, the various collimators and their functionalities are explained, and the expected system performance is summarized.
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Transparencies
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TUPCH055 | Beam Phase Measurement of Stored Bunch | pick-up, controls, insertion-device, injection | 1133 | ||||
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We developed a system to measure synchronous phase angles for all bunches stored in the storage ring using an oscilloscope with high sampling rate. Precise phase measurement of specific bunch is required from the synchrotron radiation (SR) users, especially from the time resolved spectroscopy users. In a pump and probe experiment, the trigger timing for pumping laser should be precisely adjusted to the probe SR light. The timing of SR light is affected by the accelerating RF voltages, filling pattern, bunch currents, gap positions of insertion devices and so on. At the SPring-8, the bunch currents and the synchronous phase angles for all stored bunches can be measured within 30seconds using newly developed system. The precision of the phase angle is less than 8ps. We are now preparing to deliver the information of synchronous phase angle to SR users. The detail of the measurement system and achieved performance will be presented.
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TUPCH132 | Higher Order Mode (HOM) Damper of 500 MHz Damped Cavity for ASP Storage Ring | coupling, synchrotron, storage-ring, damping | 1325 | ||||
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TOSHIBA has delivered the storage ring RF system for the Australian Synchrotron Project(ASP). Two pairs of the 500MHz Higher Order Mode(HOM) damped cavities were applied for this system. Two on-centered and one off-centered dampers were attached for damping the longitudinal HOM impedance down to less than 20kOhm/GHz. In order to reduce the coupling of off-center damper for accelerating mode and improve cooling power of damper, New HOM damper was designed by optimizing SiC absorber structure and damper antenna length using HFSS code. The design and manufacture of the new HOM damper and the test are described.
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TUPCH141 | New Developments for the RF System of the ALBA Storage Ring | simulation, storage-ring, synchrotron, klystron | 1346 | ||||
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ALBA is a 3 GeV, 400 mA, 3rd generation Synchrotron Light Source that is in the construction phase in Cerdanyola, Spain. The RF System will have to provide 3.6 MV of accelerating voltage and restore up to 540 kW of power to the electron beam. For that six RF plants, working at 500 MHz, are foreseen. The RF plants will include several new developments: 1) DAMPY cavity: the normal conducting HOM damped cavity developed by BESSY and based in the EU design; six will be installed. 2) CaCo: A cavity combiner to add the power to two 80 kW IOTs to produce the 160 kW needed for each cavity. 3) WATRAX: A waveguide transition to coaxial, specially designed to feed the DAMPY cavities due to the geometrical and cooling constrains. 4) IQ LLRF: The low level RF will be based on the IQ modulation/demodulation technique, both analogue and digital approach are being pursued. This paper describes the Storage Ring RF System and reports about the status of these new developments.
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TUPLS018 | Collimation Efficiency during Commissioning | collimation, LHC, proton, betatron | 1529 | ||||
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The design of the LHC collimation system naturally focused on understanding and maximizing the ultimate performance with all collimators in place. However, for the commissioning of the LHC it is important to analyze the collimation efficiency with certain subsets of collimators, with increased collimation gaps and relaxed set-up tolerances. Special studies on halo tracking and energy deposition have been performed in order to address this question. The expected cleaning performance and intensity limits are discussed for various collimation scenarios as they might be used during commissioning and initial operation of the LHC.
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TUPLS019 | Critical Halo Loss Locations in the LHC | optics, LHC, injection, proton | 1532 | ||||
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The requirements on cleaning efficiency in the LHC are two to three orders of magnitude beyond the needs at existing super-conducting colliders. The LHC will therefore operate in unknown territory, which can only be assessed by powerful simulation tools. Such tools have been developed at CERN over the last years, making it possible to perform detailed simulations of the LHC cleaning processes and multi-turn loss patterns around the LHC ring. The simulation includes all collimators, diluters and absorbers in the LHC. Proton loss maps are generated with a 10 cm resolution, which allows performing advanced studies for quenches of super-conducting magnets along with the analysis of the deposited energy in the machine elements. The critical locations of beam halo losses are discussed, both for the ideal machine and for various scenarios of closed-orbit distortion and beta-beating. From these results it can be shown that it is sufficient to use a limited number of BLM's for the setup and optimization of the LHC collimation system.
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TUPLS047 | An Analysis of Lumped Circuit Equation for Side Coupled Linac (SCL) | coupling, SCL, linac, booster | 1600 | ||||
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The behaviour of a SCL module is generally described by resorting to an equation system borrowed from lumped circuit theories. This description holds for a narrow frequency band (mono-modal cavity behaviour). A milestone in this field is represented by the classical analysis made by Knapp & alii where the equations allow for the resonant frequencies of the cavities and the first and second order coupling constants. Eigenvalues and eigenvectors (resonant frequencies of the system and relevant current amplitudes) are also given. We show that the system is not correct in the second and last but one equations for the case of half cell termination and non zero second order coupling constants. Due to the relevance of this formulation and of the case treated, we pay a particular attention to find the missing terms in the above mentioned equation. We suggest a correction term, having in addition a deep meaning from electromagnetic point of view. By means of this term we may justify the analytical solution given by the authors. Some numerical examples are also given showing that a discrepancy appears comparing the new equations with the results of the non-correct formulation.
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WEPCH008 | The Beta-beam Decay Ring Design | injection, lattice, resonance, ion | 1933 | ||||
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The aim of the beta-beams is to produce highly energetic beams of pure electron neutrino and anti-neutrino, coming from beta radioactive decays of the 18Ne10+ and 6He2+, both at gamma = 100, directed towards experimental halls situated in the Frejus tunnel. The high intensity ion beams are stored in a ring until the ions decay. Consequently, all the injected particles will be lost anywhere in the ring, generating a high level of losses. The ring circumference has to be a multiple of the SPS circumference. The straight sections must be as long as possible in order to maximize the useful neutrino flux. The straight section length is chosen to be about 35% of the circumference length, which gives 1-km-long arcs. The bend field in the arcs is then reasonable. The arc has been chosen as a 2Pi phase advance insertion, which improves the optical properties (dynamic aperture and momentum acceptance) and allows the easy determination of the working point by the optics of the straight sections.
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WEPCH020 | Extending the Linear Least Squares Problem for Orbit Correction in Circular Accelerators | controls, ELETTRA, feedback, simulation | 1963 | ||||
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A method for extending the linear least squares problem applicable for correcting the orbit of circular accelerators is proposed. The method is based on the definition of a suitable cost function which weighs both orbit deviations and the correction effort, that is steerer kicks. The paper presents the full derivation of the formulas and the results of simulations. The application of this method for the Global Orbit Feedback system of the ELETTRA storage ring is being evaluated.
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WEPCH025 | COD Correction at the PF Ring by New Orbit Feedback Scheme | feedback, simulation, insertion-device, electron | 1978 | ||||
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When we correct the global COD (closed orbit distortion), if we use the modified conversion matrix calculated by the eigen vector method with constraint conditions (EVC), the local orbit correction can be simultaneously done to fix the light source point in the insertion device. In the EVC, the local orbit correction is combined to the global orbit correction by the Lagrange's undetermined multiple method. In this paper, we show the machine study results at the PF Ring.
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WEPLS005 | The Target Drive for the MICE Experiment | target, vacuum, acceleration, controls | 2403 | ||||
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The MICE experiment requires a beam of low energy muons to test muon cooling. This beam will be derived parasitically from the ISIS accelerator. A novel target mechanism is being developed which will allow the insertion of a small titanium target into the proton beam halo on demand. The target must remain outside the beam envelope during acceleration, and then overtake the shrinking beam envelope to enter up to 5 mm into the beam during the last 2 ms before extraction. The technical specifications are demanding, requiring large accelerations and precise and reproducible location of the target each cycle. The mechanism must operate in a high radiation environment, and the moving parts must be compatible with the stringent requirements of the accelerator's vacuum system. A prototype linear electromagnetic drive has been built, and the performance is being measured and improved to meet the design specifications. Details of the drive, position readout and control systems will be presented, together with the performance achieved to date.
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WEPLS102 | The Construction of the Superconducting Matching Quadrupoles for the LHC Insertions | quadrupole, LHC, CERN, alignment | 2616 | ||||
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After several years of intensive effort, the construction of the superconducting matching quadrupoles for the LHC insertions is nearing completion. We retrace the main events of the project from the initial development of quadrupole magnets of several types to the series production of over 100 complex cryo-magnets, and report on the techniques developed for steering of the production. The main performance parameters for the full series, such as quench training, field quality and magnet geometry are presented. The experience gained in the production of these special superconducting magnets is of considerable value for further development of the LHC insertions.
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WEPLS103 | The Field Description Model for the LHC Quadrupole Superconducting Magnets | LHC, quadrupole, CERN, controls | 2619 | ||||
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The LHC control system requires an accurate forecast of the magnetic field and the multipole field errors to reduce the burden on the beam-based feed-back. The Field Description for the LHC (FIDEL) is the core of this forecast system and is based on the identification and physical decomposition of the effects that contribute to the total field in the magnet apertures. The effects are quantified using the data obtained from series magnetic measurements at CERN and they are consequently modelled empirically or theoretically depending on the complexity of the physical phenomena. This paper presents a description of the methodology used to model the field of the LHC magnets particularly focusing on the results obtained for the LHC Quadrupoles (MQ, MQM and MQY).
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WEPLS106 | Design, Performance and Series Production of Superconducting Trim Quadrupoles for the Large Hadron Collider | CERN, LHC, quadrupole, target | 2628 | ||||
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The Large Hadron Collider (LHC) will be equipped with several thousands of superconducting corrector magnets. Among the largest ones are the superconducting trim quadrupoles (MQTL). These twin-aperture magnets with a total mass of up to 1700 kg have a nominal gradient of 129 T/m at 1.9 K and a magnetic length of 1.3 m. Sixty MQTL are required for the LHC, 36 operating at 1.9 K in and 24 operating at 4.5 K. The paper describes the design features, and reports the measured quench performance and magnetic field quality of the production magnets. The MQTL magnet production is shared between CERN and industry. This sharing is simplified due to the modular construction, common to all twin-aperture correctors.
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WEPLS133 | Stability Study of Superconductor Magnet Power Supplies at TLS | power-supply, controls, superconducting-magnet, insertion-device | 2688 | ||||
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In this paper, performance of three power supplies schemes driving the newly-developed Superconducting Wave Length Shifter Magnet at TLS is investigated. Due to the inherent structure of the Superconducting Magnet, the main and two accessory trimming power supplies are physically correlated with each others. Due to the inherent structure, in order to achieve high performance control of the magnet, slew rate control of the main power supply and the proper operation sequence have to be properly managed, otherwise, small current disturbance can occurs, which may disgrade the stability of the performance of Superconducting Magnet.
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WEPLS141 | Operational Experience with the LHC Waveguide Mode Reflectometer | LHC, quadrupole, dipole, CERN | 2709 | ||||
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The LHC microwave mode reflectometer (assembly version) reached operational status by the end of 2005. It is now routinely used in the LHC tunnel to take data on the beam-screen of the individual LHC magnets and also groups of magnets with lengths up to 200 meter. The reflectometer operates in the frequency range from about 4GHz to 8 GHz and employs mode selective launchers. Data traces of typically 16000 data points are taken in the frequency domain with subsequent Fourier transformation into the time domain and numerical waveguide mode dispersion compensation. This paper discusses the operational aspects of the system as well as methods for clutter (fake reflection) elimination and procedures for cross-checks in case of a suspected obstacle or other fault.
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THPCH038 | The PANDA Insertion Impedance in High Energy Storage Ring of FAIR | impedance, CERN, vacuum, storage-ring | 2865 | ||||
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The PANDA insertion due to the special shape of the vacuum pipe creates a discontinuity. This was expected to be the main contribution in the impedance of the vacuum chamber. In this paper we present the results of computations dealing with this problem. From many published articles it is known that the reliability of the results depends on many factors and some time they differ from each other significantly. Therefore we have investigated the impedance of the PANDA insertion using different codes and methods, in particular, MAFIA, ABCI and the analytical estimation with the formula Yakoya recognized as a most successful theoretical estimation of the tapers. Besides, PANDA has two symmetrical T-shape insertions, which have been calculated by 3D MAFIA and compared with the results given by the diffraction theory. We have analysed the longitudinal and the transverse impedance.
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THPCH062 | Collective Effects in the Storage Ring of Taiwan Photon Source | impedance, storage-ring, insertion-device, damping | 2928 | ||||
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A new 3- 3.3 GeV synchrotron light source is proposed and named the Taiwan Photon Source (TPS). The TPS design has a natural horizontal emittance less than 2 nm-rad and low emittance coupling, which results in small beam size. The nominal bunch length in TPS storage ring is much shorter compared to the existing Taiwan Light Source, that makes the issue of parasitic heating more significant. Several small-gap insertion devices are planned to provide extremely bright x-ray photon beam. Those design features have impacts on collective beam instabilities. A preliminary study of collective effects in the TPS storage ring is presented.
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THPCH134 | Development of Insertion Device Magnetic Characterization Systems at LNLS | insertion-device, wiggler, controls, synchrotron | 3113 | ||||
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This paper describes a set of magnetic measurement systems employed in the development of insertion devices at LNLS (Brazilian Synchrotron Light Source). They are: rotating coil (which can also operate as a flip-coil), spatial field mapping using Hall probes and parallel coils (Helmholtz configuration) for magnetic blocks characterization. Although such techniques are well established, strict specifications imposed by the beam dynamics on the magnetic field quality, led to a detailed analysis of their sources of error and their minimization. All three systems have already been tested and showed excellent accuracy and repeatability when compared to typical values found in the literature.
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THPCH147 | Solid-state High Voltage Pulse Power in the 10-100 Nanosecond Regime | kicker, damping, collider, linear-collider | 3134 | ||||
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New particle accelerators, with voltages exceeding 50 kV and currents exceeding 1,000 A, require kicker magnet drivers to deliver pulsed power with durations in the 10-100 ns range. Similar levels of pulse performance are needed for state-of-the-art eximer laser systems, impulse radar transmitters, and particle accelerators for medical therapy. In addition, the processing of food using pulsed electric fields (PEF processing) has similar requirements. In this paper, DTI will review solid-state pulse power technologies capable of delivering high-voltage, high-current pulses with 10-to-100 nanosecond pulse duration. IGBTs, MOSFETs, snap-off diodes, and magnetic pulse compression will be discussed. Current research at Diversified Technologies, Inc. is exploring the impact of these switching devices and circuits on pulse wave shape, pulse repeatability, adjustability of pulse voltage, current and timing, maximum pulse rate (PRF), jitter, and robustness.
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THPCH171 | Control System of the Superconducting Insertion Device at TLS | controls, power-supply, insertion-device, cryogenics | 3197 | ||||
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There are three superconducting insertion devices installed at Taiwan Light Source. Two is under construction. These insertions enhance hard X-ray production to satisfy the research requirement of X-ray community. The control system is implemented to support the operation of all these superconducting insertion devices. The control system coordinate the operation of the main power supply and the trimming power supply to charge/discharge the magnets and provide essential interlock protection for the coils and vacuum ducts. Friendly user interface supports routine operation. Various applications are also developed to aid the operation of these insertion devices. Design consideration and details of the implementation will be summary in this report.
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THPCH194 | Investigation of Using Ferroelectric Materials in High Power Fast RF Phase Shifters for RF Vector Modulation | klystron, controls, simulation, resonance | 3248 | ||||
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A fast ferroelectric phase shifter controlled by an electric field bias is being investigated for high-power RF phase shifters in vector modulation. Such a device could be used in charged particle accelerators, allowing vector control of the RF power delivered to accelerating RF cavities. Bulk ferroelectric materials, particularly those based on barium-strontium titanate (BST) compounds, have shown promise in high-power applications because of their low loss tangent and high dielectric strength. Such materials have already been investigated for use in fast phase shifters at X-Band frequencies*. Several different compositions of BST compounds are investigated in phase shifter prototypes at 402.5 MHz and 805 MHz that could be easily adapted for future large-scale accelerator projects. The ratio of barium versus strontium in the composition is varied from sample to sample. This allows an investigation of the tradeoffs involved between dielectric strength, loss tangent, tunability, and relative permittivity. Since ferroelectrics are by nature nonlinear dielectric compounds, preliminary study on the nonlinear propagation effects is conducted through computer simulation.
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*V. P. Yakovlev et al. Fast X-Band Phase Shifter, Advanced Accelerator Concepts: Eleventh Workshop, 2004. |
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THPLS011 | Operation and Recent Development at the ESRF | feedback, ESRF, undulator, insertion-device | 3290 | ||||
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We report on the achieved performance of the ESRF storage ring as well as developments accomplished or underway. A new hybrid filling mode based on groups of bunches and a 4-bunch filling pattern are now delivered to the users. Following the increasing demand of users for beam stability, the fast orbit feedback has been upgraded. The installation of 5 m-long, 8 mm vertical aperture NEG coated aluminum chambers is progressing at a rate of one chamber per shutdown. The increase in current from 200 to 300 mA is being prepared; however, operation in this mode is still impaired by HOM driven longitudinal instabilities. To overcome this difficulty, a longitudinal feedback is being commissioned. HOM damped cavities are also under study to possibly replace the existing five-cell cavities. The policy of preventive maintenance has been continued. However, in 2005 the machine availability was affected by water leaks occurring on front-end absorbers and on one dipole crotch absorber. The crotch absorbers suffer all from the same erosion process that could be delayed by a systematic vertical realignment, leaving time for procurement and replacement of the entire pool.
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THPLS017 | Orbit Stability in the 'Low Alpha' Optics of the BESSY Light Source | storage-ring, insertion-device, synchrotron, optics | 3308 | ||||
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Running the light source during dedicated shifts in the so-called 'low alpha' mode, BESSY serves two major user groups: THz experiments take advantage of intense, coherent synchrotron radiation (CSR) generated by the short bunches. Time resolved experiments appreciate the very short, high intensity VUV and x-ray pulses in the ps range that help, e.g., prepare the high resolution, low intensity fs-slicing experiments. In the 'low alpha' mode, the sensitivity of the storage ring with respect to energy and horizontal orbit is increased by orders of magnitude while the user experiments require the same beam stability as in 'normal' mode. In this paper an overview of the operational conditions of this specific user mode, the stabilization measures taken, observations and available diagnostic results as well as the achievements and shortcomings of the adapted slow orbit feedback are given.
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THPLS023 | Wake Computations for the Beam Positioning Monitors of PETRA III | PETRA, simulation, electromagnetic-fields, vacuum | 3326 | ||||
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At DESY it is planned to convert the PETRA ring into a synchrotron radiation facility, called PETRA III, in 2007. For proper design of PETRA III it is very important to estimate the wakes due to various discontinuities along the beam pipe. This article is on the wake computations for the beam positioning monitors (BPMs) in the PETRA III beam pipe. Two computer codes, namely MAFIA and Microwave Studio, were used for the electromagnetic field computations. Convergence tests and the agreement between the results of both softwares were taken as criteria in order to validate the results.
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THPLS031 | Elettra Top-up Requirements and Design Status | injection, electron, insertion-device, ELETTRA | 3350 | ||||
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Elettra is a 2.5 GeV third generation light source in operation since 1993. To provide more stable beams to the users, we plan to operate in the so-called top-up injection mode. The first step is the substitution of the present 1GeV linac by a 100 MeV pre-injector linac and a fast cycling 2.5 GeV synchrotron booster foreseen to be in operation in 2007*. The present paper will report on the requirements for the top-up operation in terms of radiation safety, diagnostics H/S, timing, modality, etc. and the design status. In particular, a new BPM system, based on the log-ratio detectors, has been successfully commissioned on the present transfer line and linac and is ready to be deployed on the new injector and to be used by the new foreseen shot to shot transfer line booster to storage trajectory feedback system. Furthermore, in order to flatten the storage ring filling, the top-up charge will be integrated where needed. Preliminary measurements on the bunch by bunch measurement methods of the storage ring bunch charge are reported.
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*Elettra New Full Energy Injector Status Report, these proceedings. |
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THPLS039 | Upgrade and Current Status of the PF Ring Vacuum System | vacuum, photon, controls, insertion-device | 3371 | ||||
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The vacuum system for the KEK Photon Factory (PF) was extensively modified in 2005 as part of the PF ring straight-sections upgrade project. This project required replacements of the quad magnets in both northern and southern straight-sections that account for nearly two-thirds of the whole circumference. Therefore, the vacuum ducts in these new quad magnets (Q-ducts), as well as the vacuum ducts in their related bend magnets (B-ducts), needed to be replaced. The new Q-ducts have a narrower cross-section and are equipped with new 4-electrode beam position monitors, and the new B-ducts are furnished with new distributed ion pumps. After the installation of these vacuum chambers, we omitted the thermal in-situ baking, anticipating that beam scrubbing would provide more efficient cleaning. Furthermore, even pre-baking before installation was not performed for the chambers in the northern half in order to evaluate the effect of the pre-baking during the early period of the commissioning. Details of these modifications, as well as the current status of the new vacuum system, will be presented.
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THPLS053 | Status of the ALBA Project | storage-ring, synchrotron, booster, vacuum | 3401 | ||||
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ALBA is a 3 GeV light source being built near Barcelona, Spain. ALBA is optimized for high flux density and a large number of available straight sections for insertion devices (3x8 m, 12x4.2 m) in a relatively small circumference of 268.8 m. The light source should be operational in 2010, including the operation of seven beamlines, including six insertion devices. The design of the lattice and of the major components of the accelerator complex (linac and booster, magnets, RF system, vacuum system) is finish and the procurement procedure has started for the large majority of them. The construction of the building will start in the first half of 2006. This report offers an overview of the status of the project, with special emphasis in the new developments.
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THPLS085 | Nonlinear Dynamics in the SPEAR 3 Double-waist Chicane | optics, dynamic-aperture, injection, SLAC | 3475 | ||||
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A quadrupole triplet has been included in the center of a 7.6 m long chicane in SPEAR 3 to create a novel and technically challenging 'double waist' optics with betay=1.6m at the center of each of two future small-gap insertion devices. The new optics also reduces betay to 2.5m in the four adjacent 4.8m straight sections. In this paper, we discuss key issues associated with design of the machine optics, insertion device compatibility issues, optimization of dynamic aperture and initial measurements of machine performance in the new configuration.
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THPLS090 | Consideration of the Double Bend Achromatic Lattice for NSLS-II | lattice, wiggler, emittance, dynamic-aperture | 3487 | ||||
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We present the results of a study of the Double Bend Achromatic (DBA) lattice as a possible choice for the NSLS-II storage ring. The DBA possesses a large number of straight sections with easily tunable beta functions which can be used for insertion device sources and for damping wigglers to reduce emittance. The dispersive regions can be designed to minimize the strength of the chromatic correction sextupoles. A key constraint is the imposition of a limit on circumference which is closely tied to cost. We discuss optimization of the dynamic aperture by minimizing the non-linear driving terms using high-order achromatic cancellation in the non-linear lattice.
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THPLS117 | In-vacuum and FEL Undulators at Danfysik | undulator, SLS, insertion-device, FEL | 3553 | ||||
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Danfysik has recently designed and produced two in-vacuum insertion devices. The first device is a 19 mm period device made for the Swiss Light Source and the second is a 20 mm period device for SOLEIL. Both are hybrid undulators with Samarium Cobalt magnets where the SLS device is made with steel poles while the SOLEIL undulator is optimized for high peak field using Vanadium Permendur poles and relative large magnet blocks. A quasi-periodic undulator has been built for FEL applications at the FOM-Institute for Plasma Physics. The device is based on a standard pure permanent undulator design but then converted into a quasi-periodic device. The magnetic performance of the device was in excellent agreement with theoretical calculations with high suppression of the 3. and 5. harmonics. A conventional undulator has also been built for FEL applications at FZR Rossendorf. A high degree of software assistance and automation has been developed for the magnet mounting, shimming and magnetic testing of the insertion devices. This technique reduces the shimming time significantly, reduces the need for highly trained personnel and results in superior magnetic performance.
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THPLS118 | Status of the SOLEIL Insertion Devices | undulator, SOLEIL, insertion-device, polarization | 3556 | ||||
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SOLEIL is the French 2.75 GeV synchrotron radiation light source of low emittance under construction near Paris. It will provide high intensity photons covering a wide spectral range from the IR to the hard x-rays. The storage ring commissioning will start in April 2006, and the first photons in the beam lines are expected during summer 2006. The first set of Insertion Devices (ID) will be installed before the commissioning or within the first year of operation of the machine. They consist of one 640 mm period and three 256 mm period electromagnetic helical undulators, three 80 mm period Apple II type undulators, and three 20 mm period in-vacuum undulators. All these ID's make use of a wide panoply of technical solutions for generating various types of magnetic fields. Magnetic and conceptual designs were performed by SOLEIL, and the technical realisation was carried out together with the different manufacturers. The design specificities of the different types of ID's and the magnetic field characterisation and optimisation will be reported. The first commissioning on the beam of these undulators will be described.
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THPLS120 | Tracking Simulations and Dynamic Multipole Shimming for Helical Undulators | multipole, simulation, undulator, insertion-device | 3562 | ||||
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Symplectic and fast tracking simulations of an APPLE type undulator for the BESSY II storage ring are presented. The simulation is based on a multiple harmonic decomposition of the magnetic field and on a generating function approach. Because of the relatively large undulator period length of 112 mm, corrections of the dynamic multipoles are required to achieve a good dynamical aperture.
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THPLS124 | The Second Generation of Superconductive Insertion Devices for ANKA | undulator, wiggler, insertion-device, radiation | 3574 | ||||
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After the superconducting undulator SCU14 was installed and successfully started operation at ANKA in spring 2005, a second generation of superconducting insertion devices for ANKA is under development. The ANKA soft x-ray analytics beamline WERA is planned to be equipped with a superconducting elliptically polarising undulator (SCEPU) with electrically tunable polarisation, and a superconducting combined undulator/wiggler (SCUW) capable of period tripling will serve as the source for the planned ANKA imaging beamline. In this paper the studies on the ANKA superconducting EPU and the status of the SCUW-project will be reviewed.
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THPLS126 | Construction and Testing of a Pair of Focusing Undulators for ALPHA-X | undulator, electron, focusing, insertion-device | 3580 | ||||
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ALPHA-X is a four-year project shared between several research groups in the UK to build a laser-plasma accelerator and produce coherent short-wavelength radiation in an FEL. A pair of undulators for the project have been designed and built by ASTeC at Daresbury Laboratory. The undulators are 1.5m long, 100 period permanent magnet devices with a minimum gap of 3.5mm, a peak field of 0.7T and a two-plane focusing design. The devices were modelled using RADIA, and data from the magnet block manufacturer was used to sort the blocks. To optimise the trajectory in the real devices, magnetic testing (using Hall probe and flipping coil techniques) and block swapping has been performed in Daresbury's dedicated insertion device test facility. The measurements agree well with the models, and the undulators will perform well within specification.
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THPLS128 | Overview of Diamond IDs for Phase 1 | DIAMOND, wiggler, insertion-device, factory | 3586 | ||||
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Diamond Light Source is a 3GeV synchrotron currently under construction in the UK, which will be operational in early 2007. It is a third generation light source comprising 22 usable straight sections for insertion devices. Phase 1 of beamline construction will include eight Insertion Devices: five PPM in-vacuum undulators, two APPL·10-2 devices to be installed in the same straight, and one 3.5T superconducting wiggler. This paper describes the current status of construction and magnetic measurements for each of the Phase 1 devices.
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THPLS135 | The Study of Errors of ALBA Fixed Stretched Wire Bench | pick-up, alignment, undulator, insertion-device | 3601 | ||||
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The new synchrotron radiation source ALBA to be built nearby Barcelona is planned to start operation in 2009. The facility includes a laboratory for magnetic measurements laboratory devoted to IDs. The stretched wire measurement technique is widely used to obtain magnetic field integrals. This technique is based upon the displacement of a stretched wire relative to the magnetic structure to be measured. In the most usual configuration, the magnets are kept fixed while the wire is moved. This arrangement is especially well suited for measuring big structures such as full undulators or its jaws. In contrast, in the fixed stretched wire configuration the magnetic structure is moved relative to a stationary pick-up coil with a straight segment. This layout is convenient for the measurement of small units, such as individual magnet blocks or magnetic modules. These measurements allow characterising the inhomogeneities of the building blocks of an undulator. In this paper we present an exhaustive analysis of error sources and tolerance requirements for a particular design of a fixed stretched wire bench made at ALBA, based both in the ESRF, SOLEIL and BESSY previous existing designs.
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THPLS136 | Magnetic Field Multipole Measurement with Hall Probe | multipole, undulator, insertion-device, simulation | 3604 | ||||
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When assembling an insertion device before shimming, sorting algorithms are used to reduce the field errors by choosing the best arrangement of magnetic blocks. In order to carry it out, magnets to be placed in the array are measured with the Helmholtz coil. This yields the magnetic dipolar moment of each one. In fact, Helmholtz coil measurements assume a dipolar filed for each block. The development of narrow gap insertion devices yields a growing interest in the effect of magnetic inhomogeneities. Magnetic inhomogeneities introduce multipolar terms that are added to those corresponding to the multipole development of an ideal magnetic source. However, magnetic inhomogeneities are not measured so far with the Helmholtz coil, because it evaluates the magnetic field far from the magnet, and the multipolar terms decay faster than the dipolar with distance. In order to take into account inhomogeneities, a new approach could be used, based on the measurement of multipoles corresponding to each block. In this paper we propose a method for the fast measurement of the multipoles corresponding to an arbitrary magnetic block, using a Hall probe scanning along a single straight line.
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THPLS137 | Insertion Devices for the MAX IV Light Source | undulator, storage-ring, insertion-device, radiation | 3607 | ||||
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The foreseen insertion devices and expected brilliance for the MAX IV light source are presented. The planned MAX IV light source consists of three low emittance storage rings and a 3 GeV linac. The linac is used as a full energy injector. The three storage rings will be operated at 700 MeV, 1.5 GeV, and 3.0 GeV, which makes it possible to cover a large spectral range from IR to hard X-rays with insertion devices optimised for each storage ring.
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