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| MOPA003 | Testing of the LHC Magnets in Cryogenic Conditions: Operation Challenges, Status, and Outlook | dipole, cryogenics, quadrupole, collider | 250 | ||
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For the Large Hadron Collider under construction at CERN and the testing of its 1706 lattice magnets in cryogenic conditions, considerable challenges had to be overcome since 2002 to arrive at the situation of today, with semi-routine operation of the purpose built tests facility. With the setting up of an Operation Team comprising of non-expert CERN Accelerator operation staff, few in number and a large external collaboration, it was essential to develop the methodology of working in light of external collaboration limits and base it on CERN-known techniques and experience in accelerator running-in, commissioning and routine operation. A flavour of the operation tools that were necessary or developed will be given, i.e., web-based tests follow-up management & information systems, development of precisely defined ‘to do list’ of tests sequences, associated methods, procedures and strict check-lists, electronic logbooks and so forth. The presentation will briefly outline the test programme and its context & constraints, give a summary of the accomplishments so far, together with the outlook for the successful completion of the whole programme within the project goals.
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| MOPA005 | Protection Against Accidental Beam Losses at the LHC | beam-losses, proton, monitoring, dipole | 492 | ||
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Protection of the LHC against uncontrolled beam losses is of prime importance due to the very high stored beam energy. For nominal beam intensities, each of the two 7 TeV/c proton beams has a stored energy of 350 MJ threatening to damage accelerator equipment. At injection a number of passive beam absorbers must be correctly positioned and specific procedures have been proposed to ensure safe injection of high intensity. The LHC beam dump block being the only LHC element that can safety absorb the full LHC beam, it is essential that the beams are extracted unto the dump block in case of emergency. The failure time constants extend from 100 microseconds to few seconds depending on the equipment. Failures must be detected at a sufficiently early stage and transmitted to the beam interlock system that triggers the beam dumping system. To ensure safe operation the machine protection system uses a variety of systems to detect such failures. The strategy for protection of the LHC will be illustrated, with emphasis on new developments and studies that aim for an increased redundancy of the protection system.
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| MPPT037 | Design Study of Superconducting Magnets for the Super-KEKB Interaction Region | quadrupole, interaction-region, multipole, luminosity | 2470 | ||
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The KEKB accelerator has achieved the highest luminosity of 1.39E1034cm-2s-1 at June-03-2004. For getting the higher luminosity over 1E1035cm-2s-1, the KEKB accelerator group continues to study the upgraded machine of the KEKB, that is the Super-KEKB. The designed machine parameters for this Super-KEKB are the vertical beta of 3 mm at the interaction point (IP), the LER and HER currents of 9.4 A and 4.1 A, and the half crossing angle of 15 mrad for the target luminosity of 1-5E1035cm-2s-1. For achieving these beam parameters, the superconducting magnets (final focus quadrupoles and compensation solenoids) are newly required to design. The magnet-cryostats have very tight spatial constraints against the Belle particle detector and the beam pipe so that the beam and the synchrotron light do not have any interference with the beam pipe. In this design, the final focus quadrupoles generate the field gradient of 42.3 T/m and their effective magnetic lengths are 0.30m and 0.36m in each side with respect to the IP, respectively. The compensation solenoids are overlaid with the quadrupoles. We will report the design of these magnets in detail and show the difficulties for the Super-KEKB-IR.
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| MPPT040 | The LHC Magnetic Field Model | injection, dipole, coupling, sextupole | 2648 | ||
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The compensation of the dynamic field changes during the proton and ion beam injection and acceleration in the LHC requires an accurate forecast and an active control of the magnetic field in the accelerator. The LHC Magnetic Field Model is the core of this magnetic prediction system. This open loop control scheme will provide the desired field components at a given time, magnet operating current, magnet ramp-rate, magnet temperature and magnet powering history to the required precision. The model is based on the identification and physical decomposition of the effects that contribute to the total field in the magnet aperture of the LHC dipoles. By using data obtained from series measurements, these components are then quantified theoretically or empirically depending on the complexity of the physical phenomena involved. This paper presents the developments of the newly fine-tuned magnetic field model and evaluates its accuracy, reproducibility and predicting capabilities.
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| MPPT041 | Improvement of the Geometrical Stability of the LHC Cryodipoles when Blocking the Central Support Post | dipole, vacuum, laser, alignment | 2675 | ||
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The LHC will be composed of 1232 horizontally curved 16 meter long super-conducting dipole magnets cooled at 1.9K, supported within their vacuum vessel by three Glass Fiber Resin Epoxy (GFRE) support posts. The two support posts at the dipole extremities were initially designed free to slide longitudinally with respect to the vacuum vessel and the central support post was designed free to slide transversally. However the magnet shape did not retain the tight geometrical tolerances, of the order of fractions of mm, imposed by machine aperture and magnetic corrector centering requirements. Thereafter a modification to the supporting system, removing the initial transversal degree of freedom of the lower flange of the central support post with respect to the vacuum vessel, was designed and implemented. This paper describes the design of the magnet/cryostat interface with and without blockage of the central support post, analyzes the additional mechanical loads related to the modification and reviews the experimental results with respect to the requirements for beam aperture and magnetic corrector centering.
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| MPPT048 | Test Results of HTS Coil and Magnet R&D for RIA | quadrupole, dipole, radiation, superconductivity | 3016 | ||
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Funding: Work supported by the U.S. Department of Energy and by the National Science Foundation. |
Brookhaven National Laboratory is developing quadrupole magnets for the proposed Rare Isotope Accelerator (RIA) based on commercially available High Temperature Superconductors (HTS). These quadrupoles will be used in the Fragment Separator region and are one of the more challenging elements in the RIA proposal. They will be subjected to several orders of magnitude more energy and radiation deposition than typical beam line and accelerator magnets receive during their entire lifetime. The proposed quadrupoles will operate in the 20-40 K temperature range for efficient heat removal. HTS coils that have been tested so far indicate that the coils meet the magnetic field requirements of the design. We will report the test results of about 10 HTS coils and of a magnetic mirror configuration that simulates the magnetic field and Lorentz force in the proposed quadrupole. In addition, the preliminary design of an HTS dipole magnet for the Fragment Separator region will also be presented. |
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| TOAA001 | Limits of Nb3Sn Accelerator Magnets | dipole, accumulation | 107 | ||
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Funding: Work supported by the U.S. Department of Energy under Contract No. DE-AC03-76SF00098. |
Pushing accelerator magnets beyond 10T holds a promise of future upgrades to machines like the Tevatron at FermiLab and the LHC at CERN. Exhausting the current density limits of NbTi, superconductor, Nb3Sn is at the present time the only practical superconductor capable of generating fields beyond 10T. Several Nb3Sn pilot magnets, with fields as high as 16T, have been built and tested, paving the way for future attempts at fields approaching 20T. The combination of high current density and the required high magnetic fields has resulted in reduced conductor volume and significantly increased the accumulated Lorentz forces. Future coil and structure designs will be required to deal with stresses of several 100’s of MPa and forces of 10’s of MN/m. The combined engineering requirements on size and cost of accelerator magnets will require a magnet technology that diverges from the one currently used with NbTi conductor. How far can the engineering of high field magnets be pushed, what are the issues and limitations, and what tools will we need before such magnets can be used in particle accelerators. In this paper we shall address such issues and attempt to provide possible answers. |
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| TOAA010 | Serpentine Coil Topology for BNL Direct Wind Superconducting Magnets | quadrupole, dipole, octupole, multipole | 737 | ||
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Funding: Work supported by the U.S. Department of Energy under contract DE-AC-02-98-CH10886. |
BNL direct wind technology, with the conductor pattern laid out without need for extra tooling (no collars, coil presses etc.) began with RHIC corrector production. RHIC patterns were wound flat and then wrapped on cylindrical support tubes. Later for the HERA-II IR magnets we improved conductor placement precision by winding directly on a support tube. To meet HERA-II space and field quality goals took sophisticated coil patterns, (some wound on tapered tubes). We denote such patterns, topologically equivalent to RHIC flat windings, "planar patterns." Multi-layer planar patterns run into trouble because it is hard to wind across existing turns and magnet leads get trapped at poles. So we invented a new "Serpentine" winding style, which goes around 360 degrees while the conductor winds back and forth on the tube. To avoid making solenoidal fields, we wind Serpentine layers in opposite handed pairs. With a Serpentine pattern each turn can have the same projection on the coil axis and integral field harmonics then closely follow the 2D cross section. This and other special Serpentine coils properties are discussed in this paper and applied to a variety of direct wind magnet projects. |
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| TPPP050 | Novel Muon Cooling Channels Using Hydrogen Refrigeration and High Temperature Superconductor | beam-cooling, simulation, quadrupole, dipole | 3126 | ||
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Funding: This work was supported in part by DOE STTR grant DE-FG02-04ER86191. |
Ionization cooling, a method for shrinking the size of a muon beam, requires a low Z energy absorber, high-field magnets, and high gradient RF. It is proposed to use one gaseous hydrogen system to provide ionization energy loss for muon beam cooling, breakdown suppression for pressurized high-gradient RF cavities, and refrigeration for superconducting magnets and cold RF cavities. We report progress on the design of a cryostat and refrigeration system that circulates hydrogen through magnetic coils, RF cavities, and the absorber volume to achieve a safe, robust means to enable exceptionally bright muon beams. We find that the design can be greatly simplified if a high temperature superconductor can be used that has the capability to carry adequate current in fields above 10 T at a temperature above 33 K, the critical temperature of hydrogen. |
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| WPAE001 | Helium Distribution for the Superconducting Devices in NSRRC | vacuum, storage-ring, monitoring, radio-frequency | 758 | ||
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In NSRRC up to five superconducting magnets and one superconducting cavity will be installed in the storage ring. At current stage two superconducting magnets and one superconducting cavity are kept in cold condition by one 450W helium cryogenic system. The crucial stable cryogenic condition required from the superconducting cavity is hard to achieve due to the join of superconducting magnets. A second cryogenic system dedicated for the superconducting magnets is planned in the next stage. A switch valve box serves the function for the backup of two cryogenic systems for each other and a 100 meter nitrogen-shielding helium transfer line dedicated for the five superconducting magnets are installed at end of the year 2004. This paper presents the helium distribution design of the two cryogenic systems and the commission result of the recent work.
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| WPAE063 | CERN-PS Main Power Converter Renovation: How To Provide and Control the Large Flow of Energy for a Rapid Cycling Machine? | acceleration, synchrotron, pulsed-power, superconductivity | 3612 | ||
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The PS (Proton-Synchrotron) at CERN, which is part of the LHC injector chain, is composed of 101 main magnets connected in series. During a cycle (about 1 second), the active power at the magnet terminals varies from plus to minus 40 MW. Forty years ago, the solution was to insert a motor-generator (M-G) set between the AC supply network and the load. The M-G set acts as a fly-wheel with a stored kinetic energy of 233 MJ. The power converter is composed of two 12-pulse rectifiers connected in series. A renovation or replacement of the installation is planned in the near future as part of the consolidation of the LHC injectors. This paper presents a first comparison of technical solutions: - a direct connection to the 400 kV mains; - a kinetic energy storage system either by the existing or by a new “state of the art” M-G set; - a new local inductive or capacitive energy storage system. All these solutions need new power electronics equipment, which should be based on proven industrial topologies, techniques and components. The related studies will address the challenge of controlling by a modern power converter with local energy storage the positive and negative flow of energy to a rapid cycling accelerator load.
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| WOAD005 | BEPCII Interaction Region Design and Construction Status | quadrupole, vacuum, interaction-region, septum | 478 | ||
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BEPC (Beijing Electron Positron Collider) is now upgrading to a double-ring collider with a new and compact interaction region. The multi-purpose superconducting magnets and conventional dual aperture quadrupole magnets are used as final focusing quadrupole in the interaction region .The two beams collide at the interaction point with a cross angle of ±11 mrad and further beams separation is enhanced with the help of a septum bending magnet which locates just beyond the vertically focusing quadrupole and acts on the outgoing beam lines only. This paper will describe the IR design and its construction status.
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| RPPE077 | A Complete System for Operation of a Superconducting Magnet | power-supply, wiggler, controls, monitoring | 4003 | ||
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Funding: National Science Foundation. |
A complete system for operating, protecting and monitoring a superconducting magnet is described. This system is used in CESR (Cornell Electron Storage Ring) at Cornell University's Laboratory for Elementary Particle Physics (LEPP) for the CESR superconducting wigglers, part of the accelerator upgrade in pursuit of the CESR charm physics program known as CESR-c. |
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| RPPP017 | Compact Superconducting Final Focus Magnet Options for the ILC | quadrupole, extraction, septum, feedback | 1569 | ||
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Funding: Work supported by the U.S. Department of Energy under contracts DE-AC-02-98-CH10886 and DE-AC02-76SF00515. |
We present a compact superconducting final focus (FF) magnet system for the ILC based on recent BNL direct wind technology developments. Direct wind gives an integrated coil prestress solution for small transverse size coils. With beam crossing angles more than 15 mr, disrupted beam from the IP passes outside the coil while incoming beam is strongly focused. A superconducting FF magnet is adjustable to accommodate collision energy changes, i.e. energy scans and low energy calibration runs. A separate extraction line permits optimization of post IP beam diagnostics. Direct wind construction allows adding separate coils of arbitrary multipolarity (such as sextupole coils for local chromaticity correction). In our simplest coil geometry extracted beam sees significant fringe field. Since the fringe field affects the extracted beam, we also study advanced configurations that give either dramatic fringe field reduction (especially critical for gamma-gamma colliders) or useful quadrupole focusing on the outgoing beam channel. We present prototype coil winding test results and discuss our progress toward an integrated FF solution that addresses important machine detector interface issues. |
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| RPPT043 | Commissioning of the Main Magnet of Kolkata K-500 Superconducting Cyclotron | cyclotron, vacuum, power-supply, radio-frequency | 2765 | ||
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Main magnet of the K-500 superconducting cyclotron at Kolkata has been fully assembled in the cyclotron vault. The assembly includes alpha and beta superconducting coils inside the liquid helium chamber, coil tank for the outer vacuum, liquid nitrogen shield, support links, cryogenic instrumentation and 80 ton magnet frame forming the pill box structure. Cooling of the coils was started in mid-December. It took about three weeks to fill the liquid helium chamber - fully immersing the coils. All the four temperature sensors embedded in the coil are steady at about 4.4K. At this time the liquid nitrogen line for cooling the shield seems to show a leak. So, we are not cooling the shield. The helium liquefier/regrigerator of 200W capacity has been functioning well and so is the network of vacuum jacketted and liquid nitrogen cooled cryogenic transfer lines. Energization of the main magnet will begin soon. Magnetic field measurement set up is in place to start the mapping. In this presentation, our experiences with commissioning of the largest superconducting magnet in India, with stored energy 22 MJ at peak field of 6T, will be described. Some results of the magnetic field measurements will also be presented.
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| FPAT060 | An FPGA-Based Quench Detection and Protection System for Superconducting Accelerator Magnets | power-supply, extraction, quadrupole, interaction-region | 3502 | ||
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A new quench detection and protection system for superconducting accelerator magnets was developed at the Fermilab's Magnet Test Facility (MTF). This system is based on a Field-Programmable Gate Array (FPGA) module, and it is made of mostly commerically available, integrated hardware and software components. It provides most of the functionality of our existing VME-based quench detection and protection system, but in addition the new system is easily scalable to protect multiple magnets powered independently and has a more powerful user interface and analysis tools. First applications of the new system will be for testing corrector coil packages. In this paper we describe the new system and present results of testing LHC Interaction Region Quadrupole (IRQ) correctors.
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