| Paper | Title | Page |
|---|---|---|
| WEPLS001 | Secondary Particle Production and Capture for Muon Accelerator Applications | 2394 |
|
||
| Intense pulsed muon beams are required for projects such as the Neutrino Factory and Muon Collider. It is currently proposed to produce these from a high-Z target using a multi-megawatt proton driver. This paper examines the effect of proton energy on the yield and distribution of particles produced from tantalum and mercury, with further analysis using a tracking code to determine how these distributions will behave downstream, including a breakdown of loss mechanisms. Example 'muon front end' lattices are used from the UK Neutrino Factory design. | ||
| WEPLS002 | Design and Expected Performance of the Muon Beamline for the Muon Ionisation Cooling Experiment | 2397 |
|
||
| It is proposed to install a Muon Ionisation Cooling Experiment (MICE) at the ISIS facility, at Rutherford Appleton Laboratory (RAL). This experiment will be the first demonstration of ionisation cooling as a means to reduce the large transverse emittance of the muon beam, produced during the early stages of a Neutrino Factory. In order to permit a realistic demonstration of cooling, a beam of muons must be produced, possessing particular qualities, notably in emittance and momenta. This paper describes the current design for the muon beamline, outlining issues particular to the needs of the MICE experiment, and discusses its expected performance. | ||
| WEPLS003 | Simulation of MICE Using G4MICE | 2400 |
|
||
| In the Muon Ionisation Cooling Experiment (MICE), muons will be fired one by one through one or two cooling cells. The experiment will be used to optimise simulation of an ionisation cooling channel for a future Neutrino Factory. This is achieved by measuring the position of each muon in six-dimensional phase space and examining the behaviour of muons collected into bunches offline. The experiment will be run with a number of different input beams, magnet configurations, RF configurations and absorber types. We present the simulated detector and cooling performance of the MICE cooling channel using the G4MICE simulation code for a range of configurations. We detail the simulation of engineering, field and detector models and examine the implications for the cooling efficacy and measurement. | ||
| WEPLS005 | The Target Drive for the MICE Experiment | 2403 |
|
||
| 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. | ||
| WEPLS006 | Requirements for Accelerator-based Neutrino Facilities | 2406 |
|
||
| Classification: 1-A18, 3-A09, 4-A15, 6-T03 (non exhaustive). The study of neutrino oscillations offers promises of great discoveries including leptonic CP violation. The experimental programs that are under discussion pose considerable challenges to accelerator builders. Extremely high intensities are needed for classical on- and off-axis pion decay beams; novel ideas such as beta-beams and muon decay beams have been invented and are being studied. The experiments to be performed require outstanding predictability and monitoring of the neutrino flux. The challenges will be reviewed and a list of requirements will be proposed. | ||
| WEPLS007 | A Six-dimensional Muon Beam Cooling Experiment | 2409 |
|
||
| Ionization cooling, a method for shrinking the size of a particle beam, is an essential technique for the use of muons in future particle accelerators. Muon colliders and neutrino factories, examples of such future accelerators, depend on the development of robust and affordable ionization cooling technologies. A 6D cooling experiment has been proposed, incorporating a novel configuration of helical and solenoidal magnets in a prototype cooling channel. This Helical Cooling Channel (HCC) experiment is being designed with simulations and prototypes to provide an affordable and striking demonstration that 6D muon beam cooling is understood well enough to enable intense neutrino factories and high-luminosity muon colliders. Because of the large amount of expected beam cooling, helium instead of hydrogen can be used for the initial experiment, avoiding the safety complications of hydrogen. Cryostats are currently being developed using internal heat exchangers for simple, effective and safe hydrogen absorber systems to use in later cooling experiments and real cooling channels. The experimental design choices and corresponding numerical simulations are reviewed. | ||
| WEPLS009 | Summary of the Low Emittance Muon Collider Workshop (February 6-10, 2006) | 2412 |
|
||
| The Low Emittance Muon Collider workshop, held at Fermilab February 6-10, 2006 focused on the development of high-luminosity muon colliders using extreme muon beam cooling, where many constraints on muon collider designs are alleviated with beams of smaller emittance and lower intensity. The workshop covered topics related to proton drivers, targetry, muon capture, bunching, cooling, cooling demonstration experiments, bunch recombination, muon acceleration, collider lattices, interaction-point design, site boundary radiation, and detector concepts for energy frontier and Higgs particle studies. Lower emittance allows for a reduction in the required muon current for a given luminosity and also allows high energy to be attained by recirculating the beam through high frequency ILC RF cavities. The highlights of the workshop and the prospects for such colliders will be discussed. | ||
| WEPLS010 | 20 - 50 GeV Muon Storage Rings for a Neutrino Factory | 2415 |
|
||
| Muon decay ring studies are being undertaken as part of the International Scoping Study (ISS) for a Neutrino Factory. A racetrack and an isosceles triangle shaped ring are under design, initially for a muon energy of 20 GeV, but with an upgrade potential for 50 GeV. Both rings are designed with long straights to optimize directional muon decay. The neutrinos from the muon decays pass to one or two distant detectors; the racetrack ring has one very long production straight, aligned with one detector, while the triangular ring has two straights, each half as long, which can be aligned with two detectors. Lattice studies, injection, collimation, and RF system design for the large acceptance, high intensity rings are discussed and the performance of the two rings compared. | ||
| WEPLS011 | General Design Considerations for a High-intensity Muon Storage Ring for a Neutrino Factory | 2418 |
|
||
| Muon decay ring design, shielding, and compatibility with potential neutrino detector sites are a critical part of the International Scoping Study (ISS) for a neutrino factory. Two rings are under development: a racetrack and an isosceles-triangle ring initially for muon energy of 20 GeV, but upgradable to 50 GeV. Neutrinos from the muon decays in specially designed production straights can be directed to one or two distant detectors; the racetrack ring has one very long production straight, aligned with one detector, while the triangular ring has two straights, each half as long, aligned with two detectors. An initial site survey of accelerators and distant detectors has been made, along with the required tilt angles from the horizontal will be discussed here. (Lattice studies, injection, collimation, and RF system design are covered in a separate contribution to these proceedings.) Heating and activation effects of beam loss in the chamber walls and components will also be presented. | ||
| WEPLS012 | Use of Gas-filled Cavities in Muon Capture for a Muon Collider or Neutrino Factory | 2421 |
|
||
| Recent studies indicate that gas-filled cavities can provide high-gradient acceleration and simultaneous cooling for muons. In this paper we explore using these cavities in the front-end of the capture and cooling systems for muon colliders and neutrino factories. For a muon collider scenario we consider capturing the beam in a low-frequency cavity (~50 MHz) and cooling immediate after capture. For a neutrino factory, we consider capturing beam in high-frequency buckets and phase-energy rotating and cooling them using gas-filled rf cavities. Scenario variants are described and studied. | ||
| WEPLS016 | Studies of a Gas-filled Helical Muon Beam Cooling Channel | 2424 |
|
||
| A helical cooling channel (HCC) can quickly reduce the six dimensional phase space of muon beams for muon colliders, neutrino factories, and intense muon sources. The HCC is composed of solenoidal, helical dipole, and helical quadrupole magnetic fields to provide the focusing and dispersion needed for emittance exchange as the beam follows an equilibrium helical orbit through a continuous homogeneous absorber. We consider liquid helium and liquid hydrogen absorbers in HCC segments that alternate with RF accelerating sections and we also consider gaseous hydrogen absorber in pressurized RF cavities imbedded in HCC segments. In the case of liquid absorber, the possibility of using superconducting RF in low magnetic field regions between the HCC segments may provide a cost effective solution to the high repetition rate needed for an intense neutrino factory or high average luminosity muon collider. In the gaseous hydrogen absorber case, the pressurized RF cavities can be operated at low temperature to improve their efficiency for higher repetition rates. Numerical simulations are used to optimize and compare the liquid and gaseous HCC techniques. | ||
| WEPLS017 | International Scoping Study of a Future Accelerator Neutrino Complex | 2427 |
|
||
| The ISS, launched at NuFact05 to evaluate the physics case for a facility, along with options for the accelerator complex and detectors, is laying the foundations for a subsequent conceptual-design study. It is hosted by RAL and organized by the international community, with participants from Europe, Japan, and the U.S. Here we cover work of the Accelerator Group. For the 4 MW proton driver, we consider linacs, synchrotrons, and FFAG rings. For targets, issues of both liquid-metal and solid materials are examined. For beam conditioning (phase rotation, bunching, and ionization cooling), we evaluate schemes with and without cooling, the latter based on scaling FFAG rings. For acceleration, we examine scaling FFAGs and hybrid systems comprising linacs, dogbone RLAs, and non-scaling FFAGs. For the decay ring we consider racetrack and triangular shapes, the latter capable of simultaneously illuminating two different detectors at different baselines. Comparisons are made between various technical approaches to identify optimum design choices for the facility. | ||
| WEPLS018 | Optics for Phase Ionization Cooling of Muon Beams | 2430 |
|
||
| The realization of a muon collider requires a reduction of the 6D normalized emittance of an initially generated muon beam by a factor of more than 106. Analytical and simulation studies of 6D muon beam ionization cooling in a helical channel filled with pressurized gas or liquid hydrogen absorber indicate that a factor of 106 is possible. Further reduction of the normalized 4D transverse emittance by an additional two orders of magnitude is envisioned using Parametric-resonance Ionization Cooling (PIC). To realize the phase shrinkage effect in the parametric resonance method, one needs to design a focusing channel free of chromatic and spherical aberrations. We report results of our study of a concept of an aberration-free wiggler transport line with an alternating dispersion function. Resonant beam focusing at thin beryllium wedge absorber plates positioned near zero dispersion points then provides the predicted PIC effect. | ||
| WEPLS019 | Parameters for Absorber-based Reverse Emittance Exchange of Muon Beams | 2433 |
|
||
| The normalized longitudinal emittance of a muon beam after six-dimensional ionization cooling appears very small compared to the value that could be utilized or maintained after acceleration to muon collider energy. This circumstance offers the possibility for further reduction of the transverse emittance by introducing absorber-based reverse emittance exchange (REMEX) between longitudinal and transverse degrees of freedom before acceleration to high energy. REMEX follows Parametric-resonance Ionization Cooling and is accomplished in two stages. In the first stage the beam is stretched to fill the RF bucket at the initial cooling energy. In the second stage the beam is accelerated to about 2.5 GeV, where energy straggling begins to limit the absorber technique, and stretched again. The potential transverse emittance reduction and the intrinsic limitations of the REMEX technique have been analyzed earlier. In this report, we describe the required beam transport and RF parameters needed to achieve the maximum REMEX effect. | ||
| WEPLS020 | The RF Deflector for the CTF3 Delay Loop | 2436 |
|
||
| In the CLIC Test Facility 3 (CTF3) a 42 m long ring, called delay loop, is used to halve the distance between bunches in the drive beam. The compression is obtained by merging two adjacent bunch trains from the linac deflected in opposite directions by an RF device, in such a way that the first train is forced to perform a full revolution in the delay loop, while the second one passes through. The length of the ring is an odd multiple of half the distance between bunches in the beam from the linac. The RF deflector consists of two identical cavities connected to the RF power source through a hybrid junction that equally splits the power and isolates the klystron from reflections. Its innovative design, the results of electromagnetic simulations and expected performances are described, together with low level RF measurements for test and characterization of the device before installation. Preliminary recombination results with the CTF3 beam are also shown. The RF deflector has also been used to measure the length of the accelerated bunches. | ||
| WEPLS021 | The PLASMONX Project for Advanced Beam Physics Experiments | 2439 |
|
||
| The Project PLASMONX is well progressing into its design phase and has entered as well its second phase of procurements for main components. The project foresees the installation at LNF of a Ti:Sa laser system (peak power > 170 TW), synchronized to the high brightness electron beam produced by the SPARC photo-injector. The advancement of the procurement of such a laser system is reported, as well as the construction plans of a new building at LNF to host a dedicated laboratory for high intensity photon beam experiments (High Intensity Laser Laboratory). Several experiments are foreseen using this complex facility, mainly in the high gradient plasma acceleration field and in the field of mono-chromatic ultra-fast X-ray pulse generation via Thomson back-scattering. We present an innovative scheme of external injection of the SPARC beam into laser wake-field driven plasma waves. Detailed numerical simulations have been carried out to study the generation of short electron bunches, to be injected into plasma waves driven with adiabatically variable density in order to compress the bunch at injection and further accelerate it by preserving a small energy spread and good beam quality. | ||
| WEPLS022 | ILC Beam Energy Measurement based on Synchrotron Radiation from a Magnetic Spectrometer | 2442 |
|
||
| The magnetic spectrometer with a relative energy resolution of 5·10-5 was proposed for ILC beam energy measurements. The beam energy measurement is based on precise definition of the beam position at a resolution of 100 nm and B-field integral at an accuracy of 2E-5. A complementary method of the beam energy measurement is proposed at registration of synchrotron radiation (SR) from the energy spectrometer dipole magnets. The measurements of both edge horizontal positions for SR fan on a distance of 50-70 m downstream of the spectrometer magnets permit to determine the beam energy with required resolution. The main principles of the beam energy measurements based on SR, the numerical simulations of SR performed by the GEANT code and proposal of SR monitors with submicron resolution are discussed. | ||
| WEPLS023 | The Two-beam Test-stand in CTF3 | 2445 |
|
||
| The acceleration concept for CLIC, based on the two-beam acceleration scheme, where the 30 GHz RF power needed to accelerate the high energy beam is generated by a high-intensity but rather low energy drive beam, will be tested in the two-beam test-stand in CTF3. There RF-structures will be tested at full pulse length. The extreme power levels of up to 640 MW warrant a careful diagnostic system to analyze RF breakdown by observing the effect on both probe- and drive-beam but also the RF signals and secondary effects such as emitted light, vibrations, vacuum, temperatures. We describe the experimental setup and the diagnostic system planned to be installed in CTF3 for 2007. | ||
| WEPLS024 | Linear Laser Wakefield Acceleration with External Injection | 0 |
|
||
| The Laser Wakefield project at Eindhoven University seeks to separate three processes needed for controlled LWFA: Creation of a plasma channel, injection of electrons and acceleration of these electrons. This enables control over and optimization of the individual components of the accelerator. It also removes the need to operate in the non-linear wakefield regime. This allows the use of lower density plasma regimes without requiring enormous laser intensities. Using front-to-end particle tracking simulations, a setup has been designed consisting of a RF-photogun, a 'modest' 2 TW tabletop laser and a pulsed capillary discharge plasma. Together, these enable the creation of 100 MeV, 1pC bunches with a duration of 10fs. The capabilities of the setup under construction will be presented. Also the outlook of laser wakefield acceleration with external injection will be discussed. | ||
| WEPLS025 | Multi-bunch Plasma Wakefield Experiments at the Brookhaven National Laboratory Accelerator Test Facility | 0 |
|
||
|
In the plasma wakefield accelerator (PWFA), a short particle bunch or train of bunches drives a large amplitude relativistic plasma wave or wake. The wake has both transverse, focusing fields, and longitudinal fields that can accelerate trailing particles or a trailing bunch. In this experiment conducted at BNL-ATF, a CO2 laser driven IFEL modulates the energy of the 65 MeV, 1.5 ps electron bunch, which after a drift creates a train of bunches approximately 3 fs long, separated by the laser wavelength (10.6 μm or about 30 fs). The largest wake amplitude is reached when the plasma wavelength is equal to the bunch spacing: n=1·1019 e-/cc. In this case, the bunch train drives a wake with an amplitude of approximately 7 GV/m in an ablative capillary discharge plasma. This wake amplitude is much larger than that previously observed with the un-bunched beam*. With this multi-bunch PWFA scheme, the energy of an appropriately phased trailing bunch could be multiplied by a large factor, of the order of the number of drive bunches. Experimental results including plasma density diagnostic using Stark broadening, beam bunching using CTR and energy gain and loss measurements will be presented.
*V. Yakimenko et al., Phys. Rev. Lett. 91, 014802 (2003). |
||
| WEPLS028 | Improvement of Electron Generation from a Laser Plasma Cathode through Modified Preplasma Conditions Using an Artificial Prepulse | 2448 |
|
||
| We have been studying the effects of laser prepulses, plasma cavity formation, wave breaking processes in the laser plasma acceleration. It is important to control the preplasma conditions, so as to stabilize the laser plasma acceleration. The modification of the conditions of the laser plasma interaction through an artificial prepulse, magnetic fields, and/or gas density modulation will affect on the characteristics of accelerated electron beams. As the first step, we carry out experiments with an artificial prepulse. If a shockwave driven by the artificial prepulse matches the main pulse foccal position, localized wave breaking may occur effectively, and consequent electron generation will be enhanced. We use a pulse with 10% energy of the main pulse and 300 ps duration to be focused on the interaction point of the gas jet, to change the plasma distribution there. Using the single-shot diagnosis, we investigate the mechanism and technique to improve the properties of electron beams. We observed a strong correlation between the generation of monoenergetic electrons and optical guiding of the main pulse, during the interaction of 11 TW 37 fs laser pulse and He gas jet. | ||
| WEPLS029 | Monoenergetic 200fs (FWHM) Electron Bunch Measurement from the Laser Plasma Cathode | 2451 |
|
||
| A laser plasma accelerator is the most promising approach to compact accelerators that can generate femtosecond electron bunches. It is expected that the electron bunch duration less than 100fs can be achieved owing to the high frequency of plasma waves. Since the time-resolution of the fastest streak camera is only 200fs, we have to use the coherent transition radiation (CTR) measurement or E/O (electro-optical) method. We plan to perform a single-shot measurement by getting the whole CTR spectrum by a IR polychromator in near future. As the first step forward it, we used a IR bolometer with different filters and obtained the average spectrum. We can generate monoenergetic electron bunches in the condition of laser intensity 3x1019W/cm2 and electron density 6x1019cm-3. The charge is estimated to be about 10pC using ICT (Integrated Current Transformer). The electron bunch accelerated by plasma waves penetrates 300um Ti-foil, and transition radiation is emitted. We measure CTR spectrum using a bolometer. Spectrum distribution of CTR depends on the electron bunch distribution, therefore we can evaluate the bunch duration from it. In the experiment, bunch duration can be estimated. | ||
| WEPLS032 | Spin Tracking at the ILC | 2454 |
|
||
| Polarized beams will play a key role in the physics programme at the International Linear Collider (ILC). It is expected that the electron and positron sources will be able to produce beams with polarizations of about 90% and 60% respectively. However, to obtain accurate measurements it is essential to have precise knowledge and control of the polarization at the interaction point itself. It follows that the theoretical calculations used for spin tracking must be guaranteed to match the anticipated 0.1% relative measurement uncertainty of the polarimeters. To meet this need, the heLiCal collaboration is developing a computer simulation to track the evolution of the polarization of bunches of electrons and positrons from the sources to the interaction point. We have studied the beam spin dynamics throughout the ILC including spin precession and radiative spin-flip processes in the positron source, damping rings, beam delivery system and the interaction region. We present the result of these studies with special emphasis on the impact of new theoretical calculations for the CAIN bunch-bunch simulation including full spin correlations and higher-order contributions. | ||
| WEPLS033 | Cold Atom Electron Sources | 0 |
|
||
|
We are developing a completely new method of producing high-brightness electron bunches, based on extraction of electrons from an ultra-cold plasma, created by photo-ionization of a cloud of laser-cooled atoms*. In this way extremely low thermal emittances (<0.1 micron) can be reached at bunch charges of several pC. In addition, pulsed extraction leads to fs bunch lengths and tens of A peak currents without the use of ultra-fast lasers or magnetic compression. GPT simulations in realistic settings show that orders of magnitude in beam brightness may be gained compared to state-of-the-art rf photoguns. Experiments are underway, whose status will be reported.
*B. J. Claessens et al. Phys. Rev. Lett. 95, 164801 (2005). |
||
| WEPLS038 | Design of Diamond-lined Accelerator Structure Test Cavity | 2457 |
|
||
| For a high-gradient normal-conducting accelerator structure for a future multi-TeV linear collider, the main limitation to achievement of high acceleration gradient is RF breakdown. In an attempt to increase the gradient beyond limits that are acceptable for metallic structures, a diamond-lined structure is suggested. The published DC breakdown limit for CVD diamond is ~2 GV/m, but the limit has never been determined for RF fields. Here we present a design for a 34-GHz diamond-lined rectangular test cavity, operating in the symmetric LSM-1,1,6 mode with symmetric side input couplers. The goal is to produce as high electric fields as possible (approaching 1 GV/m) at the diamond surfaces with ~10 MW of input power supplied by the Omega-P/Yale 34-GHz magnicon for experiment test of dielectric strength. | ||
| WEPLS039 | Developments on a Diamond-based Cylindrical Dielectric Accelerating Structure | 2460 |
|
||
| Developments on a high gradient diamond-based cylindrical dielectric loaded accelerator (DLA) is presented. A diamond-loaded DLA can potentially sustain accelerating gradients far in excess of the limits experimentally observed for conventional metallic accelerating structures. The electrical and mechanical properties of diamond make it an ideal candidate material for use in dielectric accelerators: high RF breakdown level, extremely low dielectric losses and the highest available thermoconductive coefficient. We used the hot-filament Chemical Vapor Deposition (CVD) process to produce high quality 5-10 cm long cylindrical diamond layers. Our collaboration has also been developing a new method of CVD diamond surface preparation that reduces the secondary electron emission coefficient below unity. Special attention was paid to the numerical optimization of the coupling section, where the surface magnetic and electric fields were minimized relative to the accelerating gradient and within known metal surface breakdown limits. | ||
| WEPLS040 | Progress towards an Experimental Test of an Active Microwave Medium Based Accelerator | 2463 |
|
||
|
We have been working on an experimental test of the PASER concept, where an active medium is used to provide the energy for accelerating charged particles. Initial theoretical work in this area focused on acceleration at optical frequencies; however we have identified a candidate active material operating in the X-band: a solution of fullerene (C60) in a nematic liquid crystal has been found to exhibit a maser transition* in this frequency range. The ability to employ a microwave frequency material simplifies the construction of test structures and allows beam experiments to be performed with relatively large beam emittances. We will report results on synthesis and testing of the active material using EPR spectroscopy, design and numerical simulations of bench test structures and plans for future beam experiments.
*A. Blank et al. IEEE Trans. Microwave Theory and Techniques 46 (2137) 1998. |
||
| WEPLS042 | Design and Experimental Investigation of an X-band Multilayer Dielectric Accelerating Structure | 2466 |
|
||
| A new project to significantly improve the efficiency of high gradient DLA structures is presented. A multilayer DLA where the single dielectric layer is replaced by a multiple coaxial layers of differing permittivity have been developed. The power attenuation in the multilayer structure is reduced by the Bragg Fiber principle where the dielectric layers are used to create multiple reflections in order to confine the accelerating mode fields for the most part in the dielectric, reducing the axial current on the conducting outer boundary. A design for an X-band multilayer structure operating in the TM03 mode using alternating dielectric layers with permittivities of 38 and 9.7 is discussed. In order to transfer the RF from the rectangular waveguide to the cylindrical one at TM03 mode, a special coupling and mode conversion scheme was developed. A prototype structure has been constructed and bench test results of the multilayer 11.424 GHz accelerator is presented. | ||
| WEPLS043 | Progress of the Rossendorf SRF Gun Project | 2469 |
|
||
| In this paper we report the status and the progress of the superconducting RF gun project in Rossendorf. The gun is designed for cw operation mode with 1 mA current and 10 MeV electron energy. The cavity consists of three cells with TESLA geometry, a special designed half-cell in which the photo cathode will be inserted and a choke filter, which prevents the leakage of RF power by the coaxial line between the cathode and the cavity cell. A double tuner allows the tuning of the half-cell and the TESLA cells separately. In 2005 the fabrication of two cavities with RRR300 and RRR40 was finished. We present the results of the field measurement and the warm tuning of the cavity cells as well as the tuning and performance measurement of the choke filter. The fabrication of the double tuner has been also finished. In a test bench we measured the properties of the tuner (tuning range, resolution) at LN2 temperature. Further activities concern the diagnostic beam line of the gun, the new cathode preparation and cathode transfer system, the driver laser and the LHe transfer line. | ||
| WEPLS044 | Design of a Superconducting Cavity for a SRF Injector | 2472 |
|
||
| In a collaboration between BESSY, DESY, FZR, MBI and BINP a 3-1/2 cell superconducting RF electron gun is under development at the FZ - Rossendorf. The status of the project and the progress obtained in the last year is reported on this conference. The motivation for the design of a new gun cavity, presented in this paper, is the new FEL project at BESSY. This FEL is designed for a bunch charge of 2.5 nC and the transverse emittance should be comparable with that of the current SRF gun project. In order to compensate the high bunch charge a high electric field on the cavity axis is necessary. In the present paper we will present the design of a 1-1/2 cell cavity for a superconducting RF gun. The active length of the cavity (without beam tube) is 14.4 cm. For the magnetic peak field the conservative value of 130 mT is assumed. The obtained particle energy is 6.6 MeV, corresponding to an accelerating field strength of 45.6 MV/m . In the TESLA cavity the same magnetic peak field is connected with an accelerating field strength of approximately 31 MV/m. Tracking calculation of electron bunches are in progress and will be also reported. | ||
| WEPLS045 | Study on Low-energy Positron Polarimetry | 2475 |
|
||
| For the design of the International Linear Collider (ILC) a polarised positron source based on a helical undulator system has been proposed. In order to optimise the positron beam, i.e., to ensure high intensity as well as high degree of polarisation, a measurement of the polarisation close to the positron creation point is envisaged. In this contribution methods to determine the positron polarisation at low energies are investigated. These studies are based on simulations with an extended version of Geant4, which allows the tracking of polarised particles taking into account the spin effects. | ||
| WEPLS046 | Radiation Levels and Activation at the ILC Positron Source | 2478 |
|
||
| An undulator-based positron source is recommended as baseline design for the International Linear Collider (ILC). Photons generated by electrons passing an undulator hit a rotating target and create electron-positron pairs. The positrons are captured and accelerated. An advantage of this source is the significantly lower radiation level in comparison to a conventional positron source which uses the electron beam directly to produce electron-positron pairs. The fluxes of neutrons and photons have been calculated with the particle transport code FLUKA. The activation of the positron source components has been estimated depending on the parameters of the source. The results for undulator-based and conventional positron sources are compared and presented. | ||
| WEPLS047 | 3-1/2 Cell Superconducting RF Gun Simulations | 2481 |
|
||
| A 3-1/2 cell superconducting RF photocathode gun is being developed at Forschungszentrum Rossendorf to produce a high peak current, low emittance electron beam. This technology is essential to the realisation of many large scale facilities. The gun is designed for CW operation mode with 1 mA current and 9.5 MeV electron energy, and it will be installed at the ELBE superconducting electron linear accelerator. The gun will have a 3-1/2 cell niobium cavity operating at 1.3 GHz. The cavity consists of three cells with TESLA geometry and a specially designed half-cell in which the photocathode will be placed. Typical ERL-based projects require ~100 mA average current, and therefore suitable upgrade paths are required. Simulations have been carried out to evaluate the design and to determine suitable upgrades for higher current operation. Simulations of alternative cathode surface shapes are presented. Several couplers have been identified that can provide higher power to the cavity, whose integration and suitability has been verified. All the investigations that have identified possible solutions to higher current operation are discussed in this report. | ||
| WEPLS048 | Development of a Positron Production Target for the ILC Positron Source | 2484 |
|
||
| The future International Linear Collider (ILC) will require of order 1014 positrons per second to fulfil its luminosity requirements. The current baseline design produces this unprecedented flux of positrons using an undulator-based source. In this concept, a collimated beam of 10MeV photons produced from the action of an undulator on the main electron beam of the ILC is incident on a conversion target. Positrons produced in the resulting electromagnetic shower can then be captured, accelerated and injected into a damping ring. The international community is pursuing several alternative technologies to develop a target capable of long-term operation in the intense photon beam. In the design being developed jointly by the Cockcroft Institute, LLNL and SLAC, a thin (0.4 radiation length) water-cooled Titanium alloy target wheel of diameter 4m is rotated at approximately 1000rpm to spread the incident power of each pulse over a wide area. We present the latest target design, report on the status of the target prototypes and computer models, and review the interplay between the target technology, capture optics, photon collimator and remote-handling systems. | ||
| WEPLS049 | The Design of a Hybrid Photoinjector for High Brightness Beam Applications | 2487 |
|
||
| In this paper, we illustrate the electromagnetic and beam dynamics design procedure of a new class of photoinjector, a hybrid standing/traveling wave structure. In this device a standing wave RF gun section is integrated with a downstream traveling wave structure through a coupling cell that feeds simultaneously the two sections. We discuss the advantages in RF and beam performance of the hybrid photoinjector compared to conventional systems. The electromagnetic design has been performed using the 2D and 3D electromagnetic codes Superfish and HFSS. Results of beam dynamics simulations in different operating conditions are also discussed. | ||
| WEPLS050 | Experiments with Electron Cloud and Sources | 2490 |
|
||
| The Penning-Malmberg trap ELTRAP installed at University of Milano can provide electron clouds of several sizes for study of non-linear physics: length ranges from 0.15 to 1 m, while diameter is varied between 25 mm and 70 mm by changing the electron source: filament or planar spiral. Vortices develop both in trapped and flowing electron beams. Slow instabilities, due to the accumulation of ions inside the trap are observed and cured by clearing fields. Results as a function of plasma size are described. Plan to install a third laser modulated electron source and additional diagnostic are also summarized. | ||
| WEPLS051 | Dark Current Investigation of TTF and PITZ RF Guns | 2493 |
|
||
| The dark current is one of the limiting factor in the operation of RF guns at high gradient. The continuous request of higher brilliance sources and further emittance minimization, leads to apply higher gradients in the RF gun cavity, with the consequence of a significant dark current production. In this context we set up a collaborative effort to identify the dark current sources in the gun, in order to discriminate between the gun and cathode contribution. A critical analysis and organization of dark current measurements, taken during the operation of TTF and PITZ guns, with several cathodes operated at different accelerating fields and solenoids focusing, is presented. Potential areas of improvement are also discussed, together with a possible associated program. | ||
| WEPLS052 | High QE Photocathode at FLASH | 2496 |
|
||
| The RF gun-based photoinjector of the VUV-FEL/TTF at DESY continues to use high quantum efficiency (QE) photocathodes produced at LASA, Milano. To study the photocathode behavior during beam operation, an online QE monitoring tool has been installed. In this paper, we present the hardware and software setup for the online QE measurement and the results so far obtained. The measured QEs are usually higher than at TTF phase 1. We compare the QE values taken in the RF gun with data measured just after production with a continuous UV light source. | ||
| WEPLS053 | RF Design of a Cartridge-type Photocathode RF Gun in S-band Linac | 2499 |
|
||
| A cartridge-type photocathode RF gun is under development in collaboration with SPring-8 and Hamamatsu Photonics. Each type of cathode (Cs2Te, Mg, diamond, Ag-Cs-O) is sealed in a cartridge-type vacuum tube. Several tubes can be installed in a vacuum chamber. The cathode in the tube is inserted into a center hole in the back plate of the RF gun by a vacuum manipulator. These cartridge-type photocathodes with high QE or sensitivity for visible lights, which are prepared in a factory, can be used for a long time without vacuum breaking. Since a load-lock system for forming a new high QE film is not needed, the cartridge-type RF gun becomes compact. We are going to introduce this cartridge-type system to our linac with the BNL-GUN-IV RF gun this summer. Now, we are calculating the gun parameters of the transmission cavity which has a back plate with a center hole 8mm in diameter with SUPERFISH and simulating the beam dynamics after modifying the beam line to install the system with PARMELA. We aim to use reliable Mg and high-QE Cs2Te and try diamond and Ag-Cs-O for radiation chemistry applications. The detailed numerical design and construction will be presented. | ||
| WEPLS054 | Higher-order Effect Compensation in Magnetic Compressor for < 50 fs Electron Bunch Generation | 2502 |
|
||
| An ultrashort electron bunch is essential for pulse radiolysis, which is a pump-probe measurement based on an ultrashort electron beam and an ultrashort light. In Osaka University, a laser photocathode electron linear accelerator with a magnetic compressor has been constructed for the femtosecond electron bunch generation. An electron beam with bunch length of 98 fs was successfully generated and used in pulse radiolysis. However, an electron beam with bunch length of < 50 fs is required for development of pulse radiolysis with time resolution of 100 fs. To generate such a short bunch, higher order disadvantage effects, which are caused by the fringing fields of the magnets in the compressor, should be compensated. In this paper, a compensation technique of higher-order effects was proposed by using a nonlinear energy modulation in the bunch produced in the linear accelerator by re-phasing the linac away from the zero-crossing of the rf (i.e., away from the linear slope). In the simulation, we compressed the electron bunch into 48 fs at bunch charge of 0.1 nC. | ||
| WEPLS055 | Development of Double-decker Electron Beam Accelerator for Femto/attosecond Pulse Radiolysis | 2505 |
|
||
| The study of electron-induced reactions in femto/attosecond time region is very important for the next electron beam nanofabrication. Pulse radiolysis with time resolution of sub-picosecond, as a powerful method to study such reactions in materials, has been developed by using radio-frequency electron accelerators and ultrashort lasers. In Osaka University, a new concept of double-decker electron beam accelerator is proposed for opening next pulse radiolysis on femto/attosecond time scale. The double electron beams with time delay of 1.4ns (350ps x 4) and bunch charge of 0.5-0.6 nC were generated in a photocathode electron accelerator by injecting two laser pulses into the photocathode. The beam energy of the two beams was 31.7MeV. The transverse normalized emittance was 3~6 mm-mrad for both the beams. The front of them is converted to Cherenkov light and used as a probe light source, and the back is used as a pump source. Both electron pulses are generated by one accelerator, resulting in no time jitter between the pump electron bunch and the probe laser pulse. | ||
| WEPLS056 | R&D Status of the High-intense Monochromatic Low-energy Muon Source: PRISM | 2508 |
|
||
| PRISM is a project of a future intense low-energy muon source, which combines monochromaticity and high purity. Its aimed intensity is about $1011-1012 muons per second. The muon beams will have a low kinetic energy of 20MeV so that it would be optimized for the stopped muon experiments such as searching the muon lepton flavor violating processes. PRISM consists of a pion capture section, a pion/muon transfer section and a phase rotation ssection. An FFAG is used as the phase rotator to achieve the monochromatic muon beams. This paper will describe design status of these sections as well as construction status of PRISM-FFAG. | ||
| WEPLS057 | Equivalent Velocity Spectroscopy Based on Femtosecond Electron Beam Accelerator | 2511 |
|
||
| A new femtosecond pulse radiolysis system, which is called as "Equivalent Velocity Spectroscopy (EVS)" based on a photocathode rf linear accelerator and a femtosecond laser, is developed in ISIR for the study of primly process and ultrafast electron-induced reactions for the nanofabrication. In order to achieve a high time resolution on femtosecond scale, a femtosecond electron beam bunch produced by a photocathode accelerator and a synchronized femtosecond laser were used. The electron bunch and laser pulse were injected with an angle determined by the refractive index of the sample. The electron bunch was also rotated with a same angle, resulting in the time resolution degradation due to the velocity difference between light and the electron in the sample is thus avoided. A jitter compensation technique with a femtosecond streak camera was used to reduce the time jitter between the electron bunch and laser pulse. Moreover, in EVS, a technique of double laser pulse injection was used to improve the signal to noise ratio due to the fluctuation of the laser intensity during the measurement. | ||
| WEPLS058 | Femtosecond Single-bunch Electron Linear Accelerator Based on a Photocathode RF Gun | 2514 |
|
||
| A femtosecond single-bunch electron linear accelerator based on a photocathode rf gun was developed in Osaka University for the study of radiation-induced ultrafast physical and chemical reactions. A 32 MeV single electron bunch with a bunch length of 98 fs in rms was generated successfully in the linear accelerator with a magnet bunch compressor. The dependences of the bunch length and the transverse emittance on the bunch charge were investigated experimentally and theoretically. The higher-order effects in the magnetic field were studied and compensated successfully by using a nonlinear energy-phase correlation in the bunch produced in the linear accelerator. By using the femtosecond electron bunch, an equivalent velocity spectroscopy with a synchronized femtosecond laser, as a new method with femtosecond time-resolution, was developed for study of the ultrafast reactions or phenomena on the femtosecond time scale. | ||
| WEPLS059 | The PHIN Photoinjector for the CTF3 Drive Beam | 2517 |
|
||
| A new photoinjector for the CTF3 drive beam has been designed and is now being constructed by a collaboration among LAL, CCLRC and CERN within PHIN, the second Joint Research Activity of CARE. The photoinjector will provide a train of 2332 pulses at 1.5 GHz with a complex timing structure (sub-trains of 212 pulses spaced from one another by 333 ps or 999 ps) to allow the frequency multiplication scheme, which is one of the features of CLIC, to be tested in CTF3. Each pulse of 2.33 nC will be emitted by a Cs2Te photocathode deposited by a co-evaporation process to allow high quantum efficiency in operation (>3% for a minimum of 40 h). The 3 GHz, 2 1/2 cell RF gun has a 2 port coupler to minimize emittance growth due to asymmetric fields, racetrack profile of the irises and two solenoids to keep the emittance at the output below 20 pi.mm.mrad. The laser has to survive very high average powers both within the pulse train (15 kW) and overall (200 W before pulse slicing). Challenging targets are also for amplitude stability (<0.25% rms) and time jitter from pulse to pulse (<1ps rms). An offline test in a dedicated line is foreseen at CERN in 2007. | ||
| WEPLS060 | CLIC Polarized Positron Source Based on Laser Compton Scattering | 2520 |
|
||
| We describe the possible layout and parameters of a polarized positron source for CLIC, where the positrons are produced from polarized gamma rays created by Compton scattering of a 1.3-GeV electron beam off a YAG laser. This scheme is very energy effective using high finesse laser cavities in conjunction with an electron storage ring. We point out the differences with respect to a similar system proposed for the ILC. | ||
| WEPLS063 | Laser Driven Linear Collider | 2523 |
|
||
| We represent the details of scheme allowing long term acceleration with >10GeV/m. The basis of the scheme is a fast sweeping device for laser bunch. After sweeping the laser bunch has a slope with respect to the direction of propagation. So the every cell of accelerating structure becomes illuminated locally only for the moment, when the particle is there. Self consistent parameters allow considering this type of collider as a candidate for post-ILC era. | ||
| WEPLS064 | Wiggler for ILC Cooler | 2526 |
|
||
| We represented the concept of a wiggler with linear piecewise field dependence. This eliminates nonlinearities in wiggler. This type of wiggler can be recommended for usage in ILC cooler. | ||
| WEPLS065 | The Effect of Vaccum Vessel Permeability on the Field Quality within Dipole and Quadrupole Magnets at the Energy Recovery Linac Prototype (ERLP) at Daresbury Laboratory | 2529 |
|
||
| The Energy Recovery Linac Prototype (ERLP) is currently under construction at Daresbury Laboratory in the UK and will serve as a test bed for the investigation of technologies and beam physics issues necessary for the development of Daresbury Laboratory's Fourth Generation Light Source (4GLS) proposal. To assist with the material specification of the vacuum vessels, analyses have been done on the effect of vessel permeability on the magnetic field quality within quadrupole and dipole magnets. It is found that for dipoles where the specified maximum relative dipole field variation over the good field region is ± 1x 10-4 or for quadrupoles where the specified maximum relative gradient variation is ±1 1x10-3, the transverse size of the good field region decays unacceptably for relative permeability > 1.006. However, for the dipoles where the specified maximum relative dipole field variation is ± 1x10-3, the decay of the good field region is more gradual and would safely permit a material with relative permeability >1.006 to be used for the vacuum vessel within these dipoles. | ||
| WEPLS066 | Harmonic Measurement and Adjustment of Diamond Quadrupoles | 2532 |
|
||
| The 254 quadrupole magnets for Diamond, manufactured by Tesla Engineering Ltd, were measured for harmonic content to a level around 1 part in 104. In order to meet the demanding requirements on field quality, procedures were then developed to adjust the relative positions of the magnet quadrants such that the desired harmonic levels were achieved. This process was integrated into the analysis software so that the needed changes were specified. The measurements were performed on a seven-coil rotating coil rig, which also enabled the alignment of the magnet in five spatial degrees of freedom to the specified accuracy. In this report we describe the measurement and correction procedures and present a summary of the results that were obtained. | ||
| WEPLS067 | Magnets for the 3 GeV Booster Synchrotron for the Diamond Light Source | 2535 |
|
||
| The Diamond Booster is a full energy injector for the Diamond Storage Ring. It is designed to accelerate electrons from 100 MeV to 3 GeV at a 5 Hz repetition rate. The lattice is a missing dipole FODO lattice consisting of 22 unit cells with 36 dipoles, 44 quadrupoles, 28 sextupoles and 44 correctors, distributed around a circumference of 158.4 m. The dipole field will be ramped from 0.026 T at injection to 0.809 T at 3 GeV; the quadrupoles will have a maximum operating gradient of 15T/m. The initial design of pole tip profiles was carried at Diamond, with the magnets then manufactured by DANFYSIK A/S as part of preassembled girder units (44 in total), complete with vacuum vessels. High quality was required to meet the accelerator physics requirements of alignment, positioning accuracies and field tolerances over the required good field apertures. Materials, ramp rates and field range have been selected to obtain almost linear response during magnet ramping. This paper describes the main features of the magnetic designs and measurement results; the magnets have now been delivered and installed at Diamond. | ||
| WEPLS068 | The IASA Magnetic Field Mapping (MFM) Project | 2538 |
|
||
| The design and development of an automatic magnetic field mapping device as supporting equipment for the 10 MeV CW-Linac and its transport system at the Institute of Accelerating Systems and Applications (IASA) is presented. The MFM project aims to totally automate the operation of mapping room temperature magnetic field sources, reconstruct the 3D-field shape and reveal nonlinearities in the fridge field regions. The positioning system covers an area of 50x50 cm2 with an accuracy of less than 20 ?m in both axes; magnetic field measurements, mainly based on a Hall probe, can reach in precision the 1x 10-4 value. Several software tools for the visualization of the measured fields and for a direct comparison with theoretical estimates are also presented. | ||
| WEPLS070 | The Elettra Booster Magnets Construction Status | 2541 |
|
||
| The third generation light source ELETTRA has been in operation since 1993. A new 2.5 GeV full energy booster injector has been approved and founded last year. It will replace the existing linear injector limited to a maximum energy of 1.2 GeV. During last year, after having completed the specifications and the preliminary magnetic and mechanical design, the orders for all the magnets were assigned to two European firms. The paper reports on the magnets' construction status and the requested specifications. | ||
| WEPLS071 | Design Method for a Large Aperture Opposite-field Septum Magnet | 2544 |
|
||
| A novel design septum for Japan Proton Accelerator Research Center (J-PARC) delivers high intensity 3GeV proton beam to the 50GeV main ring is presented. The project requires the construction of the large aperture septum to accommodate the large size and high intensity injection beam. As there limitations due to the lattice size and restricted installation space, the septum must provide a large kick angle to the injection beam. Sufficient clearance between the circulating beam and the injection beam is also needed to reduce the beam loss to an acceptable level to avoid the serious radiation problem. To meet these challenging requirements, a large aperture, thin septum, opposite-field septum magnet has been developed. In this paper, we present the detail studies done for the optimization of the magnet, including DC and pulse magnet. | ||
| WEPLS072 | Results of Field Measurements for J-PARC Main Ring Magnets | 2547 |
|
||
| The mass production of J-PARC main ring magnets had been completed till the end of fiscal year 2004. Those magnets consists of 97 bending magnets with 6-m in length, 216 quadrupole magnets with 11 families and 72 sextupole magnets. We have been measured the magnetic field for all of these magnets and we will finish it in March, 2006. The obtained distributions for the BL products of bending magnets and the GL products of quadrupole magnets are within the required tolerance limits, values of which are estimated by the beam optics for COD correction, etc. The measured multi-pole components for these magnets, and so on, will be also reported. | ||
| WEPLS073 | A Super Strong Adjustable Permanent Magnet Quadrupole for the Final Focus in a Linear Collider | 2550 |
|
||
| An adjustable permanent magnet quadrupole has been fabricated to demonstrate its feasibility for use in the final focus of a linear collider. The supposed requirements for such a final focus lens are the tight stabilities of its integrated field gradient and magnetic center, plus it must have adjustable strength. The high temperature coefficient of the permanent magnet material NEOMAX is compensated by use of the MS-1 Fe-Ni alloy. The magnet has two concentric rings of NEOMAX. The replacement of the inner ring with a smaller diameter one is planned in order to reach the highest gradient with the current configuration of the quadrupole system; the system has to be scaled down in size to fit in a real linear collider final focus system. A precise magnetic field measurement system is also under fabrication that will be able to measure the magnetic center to a fraction of a micron. | ||
| WEPLS074 | SESAME Magnets System | 2553 |
|
||
| In this paper the SESAME storage ring magnet system is described. The storage ring consists of 16 bending magnets with a maximum field of 1.455 T and vertical gradient of 2.79 T/m, 32 focusing quadrupoles with a maximum gradient of 16.92 T/m, 32 defocusing quadrupoles with a maximum gradient of 10.23 T/m, 32 focusing sextupoles with a maximum differential gradient of 200 T/m2 and 32 defocusing sextupoles with the maximum differential gradient of 300 T/m2. The horizontal/vertical correctors will be embedded inside focusing/defocusing sextupoles. For the quadrupole and sextupole, a design similar to ANKA has been adopted. The magnetic and electrical design of dipoles and correctors, field profile and higher order multipoles optimization will be presented. | ||
| WEPLS077 | Considerations on the Design of the Bending Magnet for Beam Extraction System of PEFP | 2556 |
|
||
| The PEFP is designed to have two beam extraction lines at the 20 MeV end and 100MeV end for beam utilization. So, the bending magnet to extract the beam from the beam line is located among the MEBT. This implies that there is a long drift space between the focusing structures, while, from the beam dynamics study, it is recommended to make the drift space shorter. In this study, we design and compare some bending magnets to satisfy the beam dynamics requirements. | ||
| WEPLS078 | Design Study of the 30 MeV Cyclotron Magnet | 2559 |
|
||
| Korea Institute of RAdiological & Medical Sciences (KIRAMS) has been developing a 30 MeV cyclotron that is planned to be installed at Advanced Radiation Technology Institute, Jeongeup in late 2006. The AVF (Azimuthally Varying Field) magnet of the cyclotron was designed to produce 15-30 MeV proton beam with movable stripper foil. Four directions of extractions are available with two switching magnets. The overall shape of the magnet is cylindrical. The magnet has three kinds of holes for beam injection, vacuum pumps and RF system. The valley and hill gap ratio is about 20 for higher axial focusing. The designed magnet model and its magnetic properties of the KIRAMS-30 are presented. | ||
| WEPLS080 | Magnets for the Storage Ring ALBA | 2562 |
|
||
| The Storage Ring ALBA is a 3.0 GeV synchrotron light source under construction in Barcelona (Spain). The Storage Ring, has a circumference of 268.8 m and comprises 32 combined magnets, 112 quadrupoles, and 120 sextupoles. This paper will describe the design and the present state of these magnets. The combined magnet has a central field of 1.42 T and a large gradient of 5.65 T/m, since most of the vertical focusing happens at these combined magnets. The 112 quadrupoles have been designed for a maximum gradient of 22 T/m. The bore diameter will be 61 mm and the lengths range from 200 to 500 mm. Each quadrupole will be individually powered. The 120 sextupoles are divided in 9 families. There are two lengths of sextupoles 150 and 220 mm and the maximum sextupole gradient is 600 T/m2. The bore diameter is 76 mm. The sextupole magnets will also be equipped with additional coils for vertical steering, horizontal steering and quadrupolar skew correction. | ||
| WEPLS081 | Modifications to the SPS LSS6 Septa for LHC and the SPS Septa Diluters | 2565 |
|
||
| The Large Hadron Collider required the modification of the existing extraction channel in the long straight section (LSS) 6 of the CERN Super Proton Synchrotron (SPS), including the suppression of the electrostatic wire septa. The newly set up fast extraction will be used to transfer protons at 450 GeV/c as well as ions via the 2.9 km long transfer line TI 2 to Ring 1 of the LHC. The girder of the existing SPS DC septa was modified to accommodate a new septum protection element. Changes were also applied to the septum diluter in the fast extraction channel in SPS LSS4, leading to the other LHC ring and the CNGS facility. The requirements and the layout of the new LSS6 extraction channel will be described including a discussion of the design and performance of the installed septum diluters. | ||
| WEPLS082 | The Septa for LEIR Extraction and PS Injection | 2568 |
|
||
| The Low Energy Ion Ring (LEIR) is part of the CERN LHC injector chain for ions. The LEIR extraction uses a pulsed magnetic septum, clamped around a metallic vacuum chamber. Apart from separating the ultra high vacuum in the LEIR ring from the less good vacuum in the transfer line to the PS this chamber also serves as magnetic screen and retains the septum conductor in place. The PS ion injection septum consists of a pulsed laminated magnet under vacuum, featuring a single-turn water cooled coil and a remote positioning system. The design, the construction and the commissioning of both septa are described. | ||
| WEPLS083 | Consolidation of the 45-year-old CERN PS Main Magnet System | 2571 |
|
||
| After a major coil insulation breakdown on two of the 45-year-old CERN PS main magnets in 2003, an extensive magnet consolidation program has been launched. This article reviews the analysis of the magnet state before the repair and the applied major improvements. An overview is given of the production of the new components, the actual refurbishment and the commissioning of the main magnet system after 18 months shut down. | ||
| WEPLS084 | AC Field Measurements of Fermilab Booster Correctors Using a Rotating Coil System | 2574 |
|
||
| The first prototype of a new corrector package for the Fermilab Booster Synchrotron is presently in production. This water-cooled package includes normal and skew dipole, quadrupole and sextupole magnets to control orbit, tune and chromaticity of the beam over the full range of Booster energies (400 MeV-8 GeV). These correctors must make rapid excursions from the 15 Hz excitation cycle of the main synchrotron magnets, in some cases even switching polarity in approximately 1 ms at transition crossing. To measure the dynamic changes in the field during operation, a new method based on a relatively slow rotating coil system is proposed. The method pieces together the measured flux from successive current cycles to reconstruct the field harmonics. This paper describes the method and presents initial field quality measurements from the corrector prototype. | ||
| WEPLS085 | Study of RF Breakdown in Normal Conducting Structures with Various Geometries and Materials | 0 |
|
||
| RF breakdown is one of the major factors determining performance of high power rf components, rf sources and accelerating structures. We study the breakdown in 11 GHz high gradient waveguides at rf powers reaching 300 MW. We tested rectangular waveguides of two geometries which have increased surface electric and magnetic fields in comparison with a standard WR90 waveguide. We used copper, gold, molybdenum, and stainless steel as material for the waveguides. We observe rf parameters, X-rays and visible light from breakdown events. We report the results of the conditioning of these waveguides and compare these results. | ||
| WEPLS087 | Status of the Development of the FAIR Superconducting Magnets | 2577 |
|
||
| For the planned 'Facility for Antiprotons and Ion Research' (FAIR), a variety of superconducting magnets is foreseen. The synchrotrons SIS 100 and SIS 300 will use fast-pulsed superferric and superconducting cos (theta) magnets. The storage ring CR and the SuperFRS will be equipped with large-scale superferric magnets, while in the storage ring HESR RHIC-type magnets are foreseen. The status of the R&D activities will be presented. | ||
| WEPLS089 | Feasibility Study of a Permanent Magnet Made from High-Tc Bulk Superconductor | 2580 |
|
||
| A field trapping experiment using a magnetic field up to ~1.5 T was performed using high-Tc bulk superconductors. Applications of bulk high-Tc superconductors have been investigated in various fields. High-Tc superconductors are attractive since they can trap higher magnetic fields than conventional permanent magnets. The trapping experiment was done with a field of above 1 T, which can be easily produced by conventional magnets. However, achieving the desired field distribution and understanding the characteristics of the trapped field and its decay process would open up the possibility of high-Tc bulk superconductor applications in the design of magnets for particle accelerators The distribution of the trapped field and its decay process was monitored by an array of Hall sensors for different shapes of the bulk superconductors. The observations are reported on in this paper. | ||
| WEPLS090 | Full Length Superferric Dipole and Quadrupole Prototype Magnets for the SIS100 at GSI: Status of the Design and Manufacturing | 2583 |
|
||
| The SIS100, one of the two basic accelerators of the future Facility for Antiproton and Ion Research FAIR at GSI, should provide acceleration of U28+ and proton beams for 0.5 s with a pulse repetition rate of 1 Hz. In the accelerator magnetic system superferric 2 T dipoles of about 3 m length and 35 T/m quadrupoles of about 1 m length will be used. The magnet coils are made from hollow NbTi composite cable cooled with two-phase helium flow at 4.5 K. The maximum operating current of 7500 A is supposed. The lattice comprises 108 dipoles and 168 quadrupoles. The elliptic beam pipe inner sizes have been fixed to 130x60 mm2 for the dipole and 135x65 mm2 for the quadrupole The design approach is based on the improved versions of the Nuclotron fast-cycling magnets that provide significant less AC loss at 4.5 K, better quality of the magnetic field and a higher long-term mechanical stability of the magnet coils. The AC losses in the magnets for the strongest SIS100 operating cycle at 4.5 K are expected to be about 13 W/m and 17 W/m in the full length prototype dipole and quadrupole magnets respectively. | ||
| WEPLS091 | Analysis of the Superferric Quadrupole Magnet Design for the SIS100 Accelerator of the FAIR Project | 2586 |
|
||
| The heavy ion fast-cycling synchrotron SIS100 is the "workhorse", of the future Facility for Antiproton and Ion Research FAIR at GSI in Darmstadt. The main lattice parameters of the accelerator are defined now so the main engineering problems of the new superferric magnets should be analyzed and solved too. We present the results of finite element calculations and compare them with the experimental data from investigation of the model magnets to characterize the expected AC loss properties of the full length prototype quadrupole. We discuss the appropriate new coil structure aimed at minimizing the heat releases at 4.5 K, but providing the requested long-term mechanical stability against dynamic Lorentz forces and thermal cooling cycles as well. | ||
| WEPLS092 | Computer Modeling of Magnetic System for C400 Superconducting Cyclotron | 2589 |
|
||
| The superconducting cyclotron (C400) is designed at IBA (Belgium) able to accelerate carbon ions at 400 MeV/nucleon. By computer simulation with 3D TOSCA code, the cyclotron magnetic system principal parameters were estimated (pole radius 187 cm, outer diameter 606 cm, valley depth 60 cm, height 276 cm). The required isochronous magnetic field was shaped with an accuracy of ± 2 mT. Four-fold symmetry and spiralized sectors with elliptical gap (minimal 12 mm at extraction) provide the stable beam acceleration till 15 mm from the pole edge. | ||
| WEPLS093 | 3D Field Computation for the Main Prototype Magnets of the SIS100 Accelerator of the FAIR Project | 2592 |
|
||
| Fast cycling superferric magnets are planned for use in the new international accelerator Facility for Antiprotons and Ion Research (FAIR) at GSI, Darmstadt. The dipoles and quadrupoles have to provide the required field quality from the injection field of 0.25T and 4.3T/m up to the maximum values of 2.1T and 35T/m respectively. The complex 3D magnetic field distribution due to the longitudinal component Bz near the yoke end regions and the presence of eddy currents also in the bulk construction elements as well as in a mechanical stable beam pipe design can create unacceptable static and dynamic nonlinearities. The detailed knowledge of these effects is necessary to control the field quality for all operating cycles to be provided by the SIS100 accelerator. We discuss the methodical problems of 3D finite element calculations (ANSYS) of the local and the integral nonlinearities, considering also the problems caused by the various nonlinear and anisotropic material properties and by the structure elements of the yoke and beam pipe. The calculated integral static and the affected by eddy currents harmonic coefficients are presented. | ||
| WEPLS094 | 3D Magnetic Field and Eddy Current Loss Calculations for Iron Dominated Accelerator Magnets using ANSYS Compared with Results of Noncommercial Codes | 2595 |
|
||
| The design of fast ramped superferric magnets with repetition rates in the order of 1Hz requires reliable software tools to calculate the complex 3D magnetic field quality as well as the impact of eddy current and hysteresis loss. Various technological construction details should be taken into account to obtain a high field quality. We present a methodical study of these questions based on ANSYS calculations for simplified dipole models. The details of these analysis are compared with recently published results obtained by different special codes, i.e. an integral and the FIT method. The time dependences of eddy current power due to longitudinal magnetic field component at the yoke ends, the transient field distribution in the yoke volume and the total eddy current loss are investigated, choosing the identical geometry with the same magnetic and electric properties of the lamination steel used by the other codes. The conclusions for the application potential of the different methods are discussed. | ||
| WEPLS096 | Design and Calculation of a Superferric Combined Magnet for XFEL | 2598 |
|
||
| A planned European X-ray Free Electron Laser so-called XFEL is being developed within the framework of an international collaboration. The design and fabrication of a prototype of a combined magnet is part of the Spanish contribution to this project. This magnet consists of a superferric quadrupole for focusing and two dipoles (horizontal and vertical) for steering, glued around the beam tube. The magnet will be operated in a superfluid helium bath. The aperture is 78 mm. The quadrupole gradient is 35 T/m whereas each dipole field is about 0.04 T. The magnetic saturation is limited to 5% at nominal current, which is quite a challenging specification for such aperture and gradient. As the overall length of the helium vessel is just 300 mm, the calculation of the magnetic field is a pure 3-D problem which has been solved and optimized using two different FEM codes to cross-check the results. This paper also gives some guidelines about the fabrication techniques most suitable for the first prototype, which is now under construction. | ||
| WEPLS097 | Random Errors in Superconducting Dipoles | 2601 |
|
||
| The magnetic field in a superconducting magnet is mainly determined by the position of the conductors. Hence, the main contribution to the random field errors comes from random displacement of the coil with respect to its nominal position. Using a Monte-Carlo method, we analyze the measured random field errors of the main dipoles of the LHC, Tevatron, RHIC and HERA projects in order to estimate the precision of the conductor positioning reached during the production. The method can be used to obtain more refined estimates of the random components for future projects. | ||
| WEPLS098 | Experience with the Quality Assurance of the Superconducting Electrical Circuits of the LHC Machine | 2604 |
|
||
| The coherence between the powering reference database and the Electrical Quality Assurance (ELQA) is guaranteed on the procedural level. However, a challenge remains the coherence between the database, the magnet test and assembly procedures, and the connection of all superconducting circuits of the LHC. In this paper, the methods, tooling, and procedures for the ELQA during the assembly phase of the LHC will be presented in view of the practical experience gained in the LHC tunnel. The parameters measured at ambient temperature such as the dielectric insulation and the impedance transfer function of assembled circuits will be discussed. Some examples of detected polarity errors and the treatment of non-conformities will be presented. | ||
| WEPLS099 | Fault Detection and Identification Methods Used for the LHC Cryomagnets and Related Cabling | 2607 |
|
||
| Several non-standard methods for electrical fault location have been successfully developed and tested. As part of the electrical quality assurance program, certain wires have to be subjected to a (high) DC voltage for the testing of the insulation. With the time difference of spark-induced electromagnetic signals measured with an oscilloscope, fault localization within a ± 10 cm range has been achieved. Another method used and adapted for the particular needs, was the synthetic pulse time-domain reflectometry (TDR) by means of a vector network analyzer. This instrument has also been applied as a low frequency sweep impedance analyzer in order to measure fractional capacities of cable assemblies where TDR was not applicable. | ||
| WEPLS100 | Performance of LHC Main Dipoles for Beam Operation | 2610 |
|
||
| At present about 75% of the main dipoles for the LHC have been manufactured and one of the three cold mass assemblers has already completed the production. More than two third of the 1232 dipoles needed for the tunnel have been tested and accepted. In this paper we mainly deal with the performance results: the quench behavior, the magnetic field quality, the electrical integrity quality and the geometry features will be summarized. The variations in performance associated with different cold mass assemblers and superconducting cable origins will be discussed. | ||
| WEPLS101 | First Computation of Parasitic Fields in LHC Dipole Magnet Interconnects | 2613 |
|
||
| The Large Hadron Collider (LHC), now under construction at CERN, will rely on about 1600 main superconducting dipole and quadrupole magnets and over 7400 superconducting corrector magnets distributed around the eight sectors of the machine. Each type of magnets is powered by dedicated superconducting busbars running along each sector and passing through the iron yokes of the main dipole and quadruple magnets. In the numerous magnet interconnects, the busbars are not magnetically shielded from the beam pipes and produce parasitic fields that can affect beam optics. We review the 3D models which have been built with the ROXIE software package to evaluate these parasitic fields and we discuss the computation results and their potential impacts on machine performance. | ||
| WEPLS102 | The Construction of the Superconducting Matching Quadrupoles for the LHC Insertions | 2616 |
|
||
| 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. | ||
| WEPLS103 | The Field Description Model for the LHC Quadrupole Superconducting Magnets | 2619 |
|
||
| 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). | ||
| WEPLS104 | The Dependence of the Field Decay on the Powering History of the LHC Superconducting Dipole Magnets | 2622 |
|
||
| The decay amplitude of the allowed multipoles in the LHC dipoles is expected to perturb the beam stability during the injection phase and is strongly dependent on the powering history of the magnet. The effect is particularly large for the pre-cycle nominal flat-top current and duration. With possible prospects of having different genres of cycles during the LHC operation, the powering history effect must be taken into account in the Field Description Model for the LHC (FIDEL) and must hence be corrected for during machine operation. This paper presents the results of the modelling of this phenomenon. We also discuss the statistic of magnetic measurements required to guarantee that the current history effect is predicted within the specified accuracy. | ||
| WEPLS105 | Performance of the LHC Arc Superconducting Quadrupoles towards the End of their Series Fabrication | 2625 |
|
||
| The fabrication of the 408 main arc quadrupole magnets and their cold masses will come to an end in summer 2006. A rich collection of measurement and test data has been accumulated and their analysis is presented in this paper. These data cover the fabrication and the efficiency in the use of the main components, the geometrical measurements and the achieved dimensional precision, the warm magnetic measurements in the factory and the performance at cold conditions, especially the training behaviour. The scrap rate of the NbTi/Cu conductor as well as that of other components turned out to be acceptably low and the quench performance measured was in general very good. Most quadrupoles measured so far exceeded the operating field gradient with one or no quench. The multipole content at cold was measured for a limited numbers of quadrupoles as far as needed for verifying the warm-to-cold correlation. From the point of view of field quality, all quadrupoles could be accepted for the machine and the measures taken to overcome the problem of a too high permeability of a batch of collars are discussed. | ||
| WEPLS106 | Design, Performance and Series Production of Superconducting Trim Quadrupoles for the Large Hadron Collider | 2628 |
|
||
| 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. | ||
| WEPLS107 | Comparative Study of Inter-strand Coupling Current Models for Accelerator Magnets | 2631 |
|
||
| "Inter-Strand Coupling Currents" (ISCCs) contribute to field errors and losses in Rutherford-type superconducting cables in the time- transient regime. The field change induces eddy currents in loops formed by the superconducting twisted strands and the resistive matrix. In the ROXIE program two models are implemented to simulate ISCCs in a magnet cross-section: A network model uses an electric circuit to represent the geometry of the twisted strands and their resistive contacts; an analytical model simplifies the network equations to determine an equivalent cable magnetization from an average field sweep over the cable. The implementation of the models in ROXIE allows to combine them with models for "Persistent Currents" and "Inter-Filament Coupling Currents". The non-linear iron yoke can be taken into account as well. The predictions of different ISCC models with regard to losses and field errors are compared for two design versions of the LHC main dipole. We find that as far as field quality is concerned, the models perform equally well. As for losses, however, the analytical model cannot capture the complexity of the problem and computes lower losses than the network model. | ||
| WEPLS108 | High Field Solenoid Magnets for Muon Cooling | 2634 |
|
||
| Magnets made with high-temperature superconducting (HTS) coils operating at low temperatures have the potential to produce extremely high fields for use in beam lines and accelerators. The specific application of interest that we are proposing is to use a very high field (of the order of 50 Tesla) solenoid to provide a very small beta region for the final stages of cooling for a muon collider. With the commercial availability of HTS tape based on BSCCO technology with high current carrying capacity at 4.2 K, very high field solenoid magnets should be possible. In this paper we will evaluate the technical issues associated with building this magnet. In particular we will address how to mitigate the high Lorentz stresses associated with this high field magnet. | ||
| WEPLS109 | Test Results of Fermilab-built Quadrupoles for the LHC Interaction Regions | 2637 |
|
||
| The US-LHC Accelerator Project has recently completed the manufacturing and testing of the Q2 optical elements for the LHC interaction region final focus. Each Q2 element consists of two identical quadrupoles (MQXB) with a dipole orbit corrector (MQXB). The Fermilab designed MQXB has a 70 mm aperture and a peak operating gradient of 215 T/m. This paper summarizes the test results for the MQXB program with emphasis on quench performance and alignment studies. | ||
| WEPLS110 | New Measurements of Sextupole Field Decay and Snapback Effect on Tevatron Dipole Magnets | 2640 |
|
||
| To perform detailed studies of the dynamic effects in superconducting accelerator magnets, a fast continuous harmonics measurement system based on the application of a digital signal processor (DSP) has been built at Fermilab. Using this new system the dynamic effects in the sextupole field, such as the field decay during the dwell at injection and the rapid subsequent "snapback" during the first few seconds of the energy ramp, are evaluated for more than ten Tevatron dipoles from the spares pool. The results confirm the previously observed fast drift in the first several seconds of the sextupole decay and provided additional information on a scaling law for predicting snapback duration. The presented information can be used for an optimization of the Tevatron and for future LHC operations. | ||
| WEPLS112 | Study of 2-in-1 Large-aperture Nb3Sn IR Quadrupoles for the LHC Luminosity Upgrade | 2643 |
|
||
| After LHC operates for several years at nominal parameters, it will be necessary to upgrade it to higher luminosity. Replacement of the low-beta insertions with higher performance design based on advanced superconducting magnets is one of the most straightforward steps in this direction. An interesting option for a new IR design is a double bore inner triplet with separation dipoles placed in front of the focusing quadrupoles. This approach reduces the number of parasitic collisions by more than a factor of three with respect to the quadrupoles-first option and allows independent field error correction for each beam. Several designs of the 2-in-1 Nb3Sn quadrupole magnets suitable for the LHC IR upgrade have been studied, including magnets with "cold" and "warm" iron yokes based on symmetric or asymmetric coils. This paper describes the design concepts of 2-in-1 large-aperture IR quadrupoles and compares their major performance parameters, including aperture, field gradient, field quality, electromagnetic stresses in the coils, and discuss some technological aspects of magnet fabrication. | ||
| WEPLS114 | Progress on the MICE Tracker Solenoid | 2646 |
|
||
| This report describes the 400 mm warm bore tracker solenoid for the Muon Ionization Cooling Experiment (MICE). The 2.923 m long tracker solenoid module includes the radiation shutter between the end absorber focus coil modules and the tracker as well as the 2.780 meter long magnet cryostat vacuum vessel. The 2.554 m long tracker solenoid consists of two sections, a three-coil spectrometer magnet and a two-coil matching section that matches the uniform field 4 T spectrometer solenoid into the MICE cooling channel. The two tracker magnets are used to provide a uniform magnetic field for the fiber detectors that are used to measure the muon beam emittance at the two ends of the cooling channel. This paper describes the design for the tracker magnet coils and the 4.2 K cryogenic coolers that are used to cool the superconducting magnet. Interfaces between the magnet and the detectors are discussed. | ||
| WEPLS115 | Impedances in Slotted-Pipe Kicker Magnets | 2649 |
|
||
| Storage ring slotted-pipe kicker magnets based on the DELTA design are foreseen for the Metrology Light Source (MLS) of the Physikalisch-Technische Bundesanstalt currently under construction near the BESSY site. Although the slotted pipe maintains the cross-section of the storage ring vacuum chamber, image currents have to bypass the slots generating wakefields. Actually modes with substantial impedances have been revealed by simulations and verified by measurements of a kicker model for the MLS. | ||
| WEPLS117 | The Australian Synchrotron Storage Ring Dipole Power Supply | 0 |
|
||
| The Australian Synchrotron storage ring consists of 28 dipoles, 56 focusing quadrupoles, 28 defocusing quadrupoles, 98 sextupoles, 42 horizontal correctors, 56 vertical correctors and 28 skew quadrupole correctors. The 28 dipole magnets are series connected and powered by a single 1100V, 850A, 24 pulse power supply with an output stability better than 100ppm. The paper will discuss the design, testing, commissioning and control interfaces for the storage ring dipole power supply. | ||
| WEPLS118 | The 3Hz Power Supplies of the SOLEIL Booster | 2652 |
|
||
| SOLEIL is a 2.75 GeV new third generation synchrotron radiation facility under construction near Paris. The injector system is composed of a 100 MeV electron Linac pre-accelerator followed by a full energy (2.75 GeV) booster synchrotron. A repetition rate of 3Hz is required for the booster for the filling of the Storage Ring together with the need for discontinuous operation for top-up filling mode. Based on digital regulation loop, the four power supplies (2 for the dipoles 600 A x 1000 V and 2 for the quadrupoles 250 A x 450 V) reach the current tracking tolerance specification of 10-3. The aim of this paper is to describe the main issues from the loads to the mains network through the power converters that are essential to reach the required performances. | ||
| WEPLS119 | Power Converters for the ISIS Second Target Station Project (TS-2) | 2655 |
|
||
| The Extract Proton Beamline to the ISIS second target station will require magnets to be powered by ac/dc power converters. A total of 50 magnets, quadrupole and dipole, require high stability dc current converters over a large dynamic range from several kW to 600kW. There is also a requirement for two 10Hz pulsed magnets to extract the proton beam from the present 50Hz target beamline, and hence specially designed power supplies are necessary. This paper describes the selection process, types of topology considerations and final selections. | ||
| WEPLS122 | Multiphase Resonant Power Converter for High Energy Physics Applications | 2658 |
|
||
| Accelerators used for experiments in high-energy physics require very high power radio frequency sources to provide the energy needed to accelerate the particles. The RF power needs to be stable and predictable such that any variation in the supplied RF power has a limited and acceptable impact on the accelerated beam quality. This paper considers the design of a "long-pulse" modulator supply rated at 25kV, 10A (250kW peak power, duty ratio 10%, 25kW average power, pulse length ≈ 1 − 2ms). The supply is based on direct modulation of a multi-phase resonant power supply, fed by an active rectifier. The objectives of the development are to produce a compact power supply, with low stored energy and with high power quality at the utility supply. The paper provides a brief overview of the technology, followed by a discussion of the design choices. Initial results from the laboratory prototype will be included. | ||
| WEPLS123 | Initial Experimental Results of a New Direct Converter for High Energy Physics Applications | 2661 |
|
||
| This paper presents practical results for a new type of power supply for high energy physics CW applications. The converter is a direct topology operating with a high frequency (resonant) link. Losses are minimised by switching at zero current. High operating frequency reduces the filter and transformer size. The transformer uses the latest nano-crystalline materials to further reduce losses. Where possible, circuit elements are incorporated into the transformer to reduce the physical size of the converter. Design of this transformer to accommodate the insulation, VA rating and circuit elements is non-trivial. The Radio Frequency power generated is stable and predictable, whilst the reduced energy storage in filter components removes the need for crowbar circuits. Potential benefits of this converter when compared to conventional approaches are discussed. These include reduced energy storage, reduced turn-on time and enhanced energy density when compared with existing topologies. Preliminary practical results are promising and are presented along with simulation results. | ||
| WEPLS124 | Diamond Booster Magnet Power Converters | 2664 |
|
||
| This paper will describe the design, factory tests, commissioning and early operation of the Diamond Booster Power Converters. The Power Converters covered are the Dipole, Quadrupole with two outputs, two bi-polar Sextupoles and 44 Steerers. The actual achieved performance will be compared with the specification and the extensive modelling that was carried out during the design phase. The design includes measures to enhance the reliability of the power converters, such as redundancy, plug-in modularity, component de-rating and component standardisation. All the Diamond power converters use the same digital controller, manufactured under licence from the Paul Scherrer Institute. | ||
| WEPLS125 | Diamond Storage Ring Magnet Power Converters | 2667 |
|
||
| The DC Magnet Power Converter requirements for the Storage Ring of the Diamond Project are described together with performance, commissioning and initial operating experience. In addition to meeting the required performance, emphasis during the design phase was placed on reliability and minimising the mean time to repair a power converter. A modular design, built-in redundancy, EMC filtering and testing, component de-rating and standardisation have all been adopted. The power modules for the 200A supplies were subject to highly accelerated stress screening. All converters are switched mode with full digital control and a common control interface. Every power converter appears identical to the Controls Network, from the lowest power corrector up to the 800 kW Storage Ring Dipole Converter. | ||
| WEPLS126 | CNAO Resonance Sextupole Magnet Power Converters | 2670 |
|
||
| The CNAO Resonance Sextupole Magnet Power Converter requirements for the Storage Ring of the CNAO Project are described together with performance and initial operating experience. In particular the achieved performances will be compared with the specification and the extensive modelling that was done during the design phase. Not only the tight required performances were emphasized during the design phase but also particular attention was put on reliability and minimization of the repairing time (MTTR). Some fundamental criteria, like component de-rating and standardisation, have also been taken into account during the component choice phase. All converters adopt the switching technology with full digital control and a common control interface, that, as for the other CNAO power converters, uses the same digital controller, under licence from the Diamond Light Source. | ||
| WEPLS127 | CNAO Storage Ring Dipole Magnet Power Converter 3000A / ±1600V | 2673 |
|
||
| This paper will describe the design and simulations of the CNAO Dipole Power Converter rated 3000A / ±1600V. The Power Converter will feed the 16+1 synchrotron bending dipole magnets of the CNAO Storage Ring. The actual design confirms how the choice of a 24-pulses, 4 bridges series-parallel connected, active filter, bipolar voltage, meets the stringent requested technical specification ( 10-5 of maximum current for the output current residual ripple and setting resolution). The extensive modelling will also be presented. The design includes the strength of the topology design, component de-rating and component standardisation. As the other CNAO power converters, the Storage Ring Dipole Power Converter uses the same digital controller, under licence from the Diamond Light Source. | ||
| WEPLS128 | The Italian Hadrontherapy Center (CNAO): A Review of the Power Supply System for Conventional Magnets | 2676 |
|
||
| A hadron (Carbon/Proton) medical centre based on a synchrotron accelerator dedicated to the cure of deep tumours is under construction in Pavia (Italy) under the joint responsibility of CNAO (Centro Nazionale di Adroterapia Oncologica) and INFN (Istituto Nazionale di Fisica Nucleare). This paper describes the power supply system, made up of about 200 units designed by LNF, and whose converters for the synchrotron ring and related low, medium and high energy transfer lines are now under construction by the major Italian companies. The power supplies requirements and electrical characteristics will be reported describing the most interesting topologies that fulfill the requested performances together with the main features of each power supply topology. Synchrotron dipoles, quadrupoles, sextupoles and resonance sextupole power supplies have tight characteristics with respect to precision class (current resolution, residual ripple, short-long term stability, etc.) that range from 5 ppm to 500 ppm, fast dynamical response with bandwidth up to some hundreds hertz, high power from tens of kW to many MW and output current ranging from hundreds of A to 3 kA. | ||
| WEPLS129 | Upgrade Scheme for the J-PARC Main Ring Magnet Power Supply | 2679 |
|
||
| Japan Proton Accelerator Research Complex (J-PARC) is under construction at the Tokai campus of Japan Atomic Energy Agency (JAEA) as a joint project between KEK and JAEA. The accelerator complex, which is constructed as a 200 MeV linac, a 3 GeV RCS synchrotron, and a main ring in phase I. The main ring magnet power supply is constructing as the energy of 40 GeV in phase I and will upgrade up to 50 GeV in phase II. A large amount of pulse electric power, which is + 115 MW and -55 MW peak-to-peak, is required for 50 GeV operation and this large pulse power will give unallowable disturbances to a power network. In order to compensate the disturbances to allowable level, we need some energy storage system. A SMES system will be one of the promising means for the purposes as well as the fly-wheel system. We will describe some energy storage system and also the increasing of repetition rate without energy storage system. | ||
| WEPLS131 | Programmable Power Supply for Distribution Magnet for 20-MeV PEFP Proton Linac | 2682 |
|
||
| The distribution magnet is powered by bipolar switching-mode converter that is employed IGBT module and has controlled by a DSP (Digital Signal Process). This power supply is operated at 350A, 5 Hz programmable stair output for beam distribution to 5 beamlines of 20-MeV PEFP proton linac. Various applications for the different power supply are made simple by software. This paper describes the design and test results of the power supply. | ||
| WEPLS132 | New Magnet Power Supply for PAL Linac | 2685 |
|
||
| Since the completion of PLS in 1994, PLS Linac magnet power supply(MPS) has been operated for 12 years with 12-bit resolution and 0.1% stability. Improvement in the resolution and the reliability of the Linac MPS is highly required now for the stable beam injection and 4th generation light source research. To improve MPS, we developed new compact MPS of 16-bit resolution and 20ppm stability using four-quadrant switching scheme with 50kHz MOSFET switching device. Bipolar MPS for corrector magnet consists of main power board, control power board, regulator board and CPU board. Size of each board is only 100mm width and 240mm depth. Unipolar MPS for quadrupoles and solenoid magnets is composed by parallel-operation of two main power boards, doubling the current output. Output of MPS is 10V, ±10A for the bipolar and 50V, 50A for the unipolar magnet. In this paper, we report on the development and characteristics of the new MPS for PAL linac. | ||
| WEPLS133 | Stability Study of Superconductor Magnet Power Supplies at TLS | 2688 |
|
||
| 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. | ||
| WEPLS134 | Design and Modeling of the Step Down Piezo Transformer | 2691 |
|
||
| The energy conversion and the step down voltage waveform of the piezo transformer are required to achieve optimal working condition of the resonate frequency. To meet this requirement, a reliable and precise instrument is needed to scan the resonated point of the piezo transformer such that the piezo transformer's output performance can meet required specification. In this paper, design and modeling of a new step down piezo transformer deployed in NSRRC is described. This step down piezo transformer is capable of delivering energy conversion with high efficiency performance, which is better than traditional transformer, and the voltage transfer ratio is correct. The simulation circuit model used to develop driver circuit of the piezo transformer is also included in the design of this new step down transformer. It has been tested and proven to be working well in power conversion with excellent efficiency and reliability. | ||
| WEPLS135 | Piezoelectric Transformer Based Continuous-conduction-mode Voltage Source Charge-pump Power Factor Correction Electronic Ballast | 2694 |
|
||
| This paper presents the piezoelectric transformer (PT) based continuous-conduction-mode (CCM) voltage source (VS) charge-pump (CP) power factor correction (PFC) electronic ballast. By replacing L-C resonant tank and transformer in the conventional CCM VS CP PFC electronic ballast with PT, the cost and volume can be reduced. The main drawback of conventional electronic ballast is that the input current has a narrow conduction angle, which causes rich harmonic that pollute the power system. However, the conventional CCM VS CP PFC electronic ballast is able to solve this problem but still require larger volume. Since the equivalent circuit of PT is identical to the conventional L-C resonant tank used in CCM VS CP PFC electronic ballast, the L-C resonant tank can be replaced by the PT to reduce the cost and volume. In addition, the inherent input capacitance of the PT works as a turn-off snubber for the power switches to decrease the turn-off voltage spikes and thus reduces the turn-off losses of the switches. The results show that the electronic ballast using PT achieved high power factor and the switches can be operated under ZVS condition. | ||
| WEPLS136 | Pulsed Magnet Power Supplies for Improved Beam Trajectory Stability at the APS | 2697 |
|
||
| New power circuit and control electronics have been implemented in the septum power supplies at the Advanced Photon Source (APS). The goal was to meet a low pulse-to-pulse relative amplitude jitter of about ± 5·10-4 for trajectory stability in the booster-to-storage ring transport line. The original power supply design produced a jitter of ± 15e-4, which made injection tuning difficult. The jitter for the two new booster pulsed magnet supplies is now 1.1e-4, as inferred by a beam-based statistical analysis. A common design was made for all of the septum magnet power supplies at the APS. The system, regulation algorithms, the results achieved, and the current regulation stability issues will be discussed. | ||
| WEPLS138 | Operation Status and Statistics of the KEK Electron/Positron Linac | 2700 |
|
||
| The KEK electron/positron linac has been operated since 1982, surpassing the total operation time of more than 100,000 hours. It delivers four different beams to four different rings quite stably, even frequently switching beam modes. The operation time per year has reached 7,000 hours since 1999 when the KEKB entered a normal operation mode. Operation status and statistics will be reported with the emphasis on continuing efforts in various kinds of machine improvements, which have ensured the stable operation. | ||
| WEPLS139 | Operational Status of Klystron-modulator System for PAL 2.5-GeV Electron Linac | 2703 |
|
||
| The klystron-modulator(K&M) system of the Pohang Accelerator Laboratory (PAL) generates high power microwaves for the acceleration of 2.5 GeV electron beams. There are 12 modules of K&M system to accelerate electron beams up to 2.5 GeV nominal beam energy. One module of the K&M system consists of the 200 MW modulator and an 80 MW S-band (2856 MHZ) klystron tube. The total accumulated high-voltage run-time of the oldest unit among the 12 K&M systems has reached nearly 88,000 hours as of December 2005. The overall system availability is well over 95%. In this paper, we review the overall system performance of the high-power K&M system and the operational status of the klystrons and thyratron lifetimes, and the overall system's availability will be analyzed for the period of 1994 to December 2005. | ||
| WEPLS140 | Update and Summary of the Dependability Assessment of the LHC Beam Dumping System | 2706 |
|
||
| The LHC Beam Dumping System (LBDS) must be able to remove the high intensity beams from the LHC accelerator on demand, at any moment during the operation. As the consequences of a major failure can be very severe, stringent safety requirements were imposed on the design. The final results of an in-depth dependability analysis on the LBDS are summarised, for one year of operation and different operational scenarios. The trade-off between safety and availability is discussed, along with the benefit from built-in features like redundancy, on-line surveillance and post-mortem diagnostics. | ||
| WEPLS141 | Operational Experience with the LHC Waveguide Mode Reflectometer | 2709 |
|
||
| 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. | ||
| WEPLS142 | The Importance of Layout and Configuration Data for Flexibility during Commissioning and Operation of the LHC Machine Protection Systems | 2712 |
|
||
| Due to the large stored energies in both magnets and particle beams, the LHC requires a large inventory of machine protection systems, as e.g. powering interlock systems, based on a series of distributed industrial controllers for the protection of the more than 10,000 normal and superconducting magnets. Such systems are required to be at the same time fast, reliable and secure but also flexible and configurable to allow for automated commissioning, remote monitoring and optimization during later operation. Based on the generic hardware architecture of the LHC machine protection systems presented at EPAC 2002 and ICALEPS 2003, the use of configuration data for protection systems in view of the required reliability and safety is discussed. To achieve the very high level of reliability, it is required to use a coherent description of the layout of the accelerator components and of the associated machine protection architecture and their logical interconnections. Mechanisms to guarantee coherency of data and repositories and secure configuration of safety critical systems are presented. This paper focuses on the first system being commissioned, the complex magnet powering system. | ||
| WEPLS143 | SLS Operation Management: Methods and Tools | 2715 |
|
||
| Users of 3rd generation synchrotron light sources desire not only a high flux on their samples and sub-micron beam stability, they expect at the same time a beam availability close to 100 percent. To reach and maintain a very high availability put special demands on the operation management of a light source. We will illustrate the procedures used at the Swiss Light Source (SLS) to deal with beam interruptions and explain the tools used for operation management. | ||
| WEPLS144 | ES&H Issues for Design and Operation of Linear Colliders | 0 |
|
||
| We consider optimization of the generalized luminosity per unit cost of a linear collider in the current ES&H era. Several specific examples, running over the length of the LC, beginning at the source and ending at the dump suggest that both costs (capital and operating) and the environmental issues can be improved in a mutually compatible way. Thus, a RoHS by any other name such as WEES or OSHA need not present thorny problems requiring unexpected technology R&D but rather a push to leverage the many recent advances that might otherwise be avoided. While not mainstream, the physics is challenging and the true amortized cost may be seriously underestimated by ignoring such issues. As example, the entire, interior surface of a laser driven RF gun involves interesting materials science where the space requires continuous UHV to sustain stable and acceptable quantum efficiency as well as avoid RF breakdown damage in an environment that is also subject to radiation damage that can reduce output from window damage. Rad hard systems can be like bug-proof software. They don't have to be overly slow, large or heavy and provide opportunities to innovate and justify the cost of such systems. |