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Finite Element Model of Training in the superconducting quadrupole magnet SQ02

Description: This paper describes the use of 3D finite element models to study training in superconducting magnets. The simulations are used to examine coil displacements when the electromagnetic forces are cycled, and compute the frictional energy released during conductor motion with the resulting temperature rise. A computed training curve is then presented and discussed. The results from the numerical computations are compared with test results of the Nb{sub 3}Sn racetrack quadrupole magnet SQ02.
Date: November 1, 2007
Creator: Caspi, Shlomo & Ferracin, Paolo
Partner: UNT Libraries Government Documents Department

Quench Protection and Magnet Supply Requirements for the MICEFocusingand Coupling Magnets

Description: This report discusses the quench protection and power supply requirements of the MICE superconducting magnets. A section of the report discusses the quench process and how to calculate the peak voltages and hotspot temperature that result from a magnet quench. A section of the report discusses conventional quench protection methods. Thermal quench back from the magnet mandrel is also discussed. Selected quench protection methods that result in safe quenching of the MICE focusing and coupling magnets are discussed. The coupling of the MICE magnets with the other magnets in the MICE is described. The consequences of this coupling on magnet charging and quenching are discussed. Calculations of the quenching of a magnet due quench back from circulating currents induced in the magnet mandrel due to quenching of an adjacent magnet are discussed. The conclusion of this report describes how the MICE magnet channel will react when one or magnets in that channel are quenched.
Date: June 8, 2005
Creator: Green, Michael A. & Witte, Holger
Partner: UNT Libraries Government Documents Department

The Role of Reluctance in PM Motors

Description: The international research community has lately focused efforts on interior permanent magnet (IPM) motors to produce a traction motor for hybrid electric vehicles (HEV). One of the beneficial features of this technology is the additional torque produced by reluctance. The objective of this report is to analytically describe the role that reluctance plays in permanent magnet (PM) motors, to explore ways to increase reluctance torque without sacrificing the torque produced by the PMs, and to compare three IPM configurations with respect to torque, power, amount of magnet material required (cost), and percentage of reluctance torque. Results of this study will be used to determine future research directions in utilizing reluctance to obtain maximum torque and power while using a minimum amount of magnet material.
Date: June 16, 2005
Creator: Otaduy, P.J.
Partner: UNT Libraries Government Documents Department

The Design of Large Cryogenic Magnet Coils : Paper No. 2

Description: Abstract: "Preliminary design and experimental work aimed toward fabrication of large magnet coils with encapsulated sodium conductors is outlined. Aspects of cooling cycles are discussed along with heat transfer, thermal stability, and the mechanical reinforcement of such coils."
Date: October 30, 1959
Creator: Post, Richard F. & Taylor, C. E.
Partner: UNT Libraries Government Documents Department

The Inductive Coupling of the Magnets in MICE and its Effect onQuench Protection

Description: The inductive coupling between various MICE magnet circuits is described. The consequences of this coupling on magnet charging and quenching are discussed. Magnet quench protection is achieved through the use of quench-back. Calculations of the quenching of a magnet due to quench-back resulting from circulating currents induced in the magnet mandrel due to quenching of an adjacent magnet are discussed. This report describes how the MICE magnet channel will react when magnets in that channel are quenched.
Date: September 8, 2005
Creator: Green, Michael A. & Witte, Holger
Partner: UNT Libraries Government Documents Department

A protype dipole septum magnet for fast high current kicker systems

Description: A dipole "septum" magnet without a material septum has been designed and tested as part of a fast beam kicker system for use in intense, electron-beam induction accelerators. This septum magnet is a simple, iron-based electromagnet with two static, oppositely oriented dipole field regions used to provide further separation of beam centroids given a small angle kick by a fast beam kicker. The magnet geometry includes removable pole pieces to allow experimental flexibility. Field errors experienced by the beam depend crucially on the magnitude of the initial kick that provides displacement of the beam centroids from the transition region between the two dipole field regions. Results of simulations are reported.
Date: March 29, 1999
Creator: Wang, L F; Caporaso, G J; Chen, Y J; Lund, S M; Poole, B R & Brown, T F
Partner: UNT Libraries Government Documents Department

Correction magnets for the Fermilab Recycler Ring

Description: In the commissioning of the Fermilab Recycler ring the need for higher order corrector magnets in the regions near beam transfers was discovered. Three types of permanent magnet skew quadrupoles, and two types of permanent magnet sextupoles were designed and built. This paper describes the need for these magnets, the design, assembly, and magnetic measurements.
Date: May 27, 2003
Creator: al., James T Volk et
Partner: UNT Libraries Government Documents Department

Nb3Sn accelerator magnet development around the world

Description: During the past 30 years superconducting magnet systems have enabled accelerators to achieve energies and luminosities that would have been impractical if not impossible with resistive magnets. By far, NbTi has been the preferred conductor for this application because of its ductility and insensitivity of Jc to mechanical strain. This is despite the fact that Nb{sub 3}Sn has a more favorable Jc vs. B dependence and can operate at much higher temperatures. Unfortunately, NbTi conductor is reaching the limit of it usefulness for high field applications. Despite incremental increases in Jc and operation at superfluid temperatures, magnets are limited to approximately a 10 T field. Improvements in conductor performance combined with future requirements for accelerator magnets to have bore fields greater than 10 T or operate in areas of large beam-induced heat loads now make Nb{sub 3}Sn look attractive. Thus, laboratories in several countries are actively engaged in programs to develop Nb{sub 3}Sn accelerator magnets for future accelerator applications. A summary of this important research activity is presented along with a brief history of Nb{sub 3}Sn accelerator magnet development and a discussion of requirements for future accelerator magnets.
Date: June 23, 2003
Creator: Lamm, Michael J.
Partner: UNT Libraries Government Documents Department

Towards a new LHC interaction region design for a luminosity upgrade

Description: After the LHC operates for several years at nominal parameters, it will be necessary to upgrade it for higher luminosity. Replacing the low-{beta} insertions with a higher performance design based on advanced superconducting magnets is one of the most straightforward steps in this direction. Preliminary studies show that, with magnet technology that is expected to be developed by early in the next decade, a factor of 2 to 5 reduction in {beta}* could be achieved with new insertions, as part of an upgrade aimed at a factor of 10 luminosity increase. In this paper we survey several possible second generation LHC interaction regions designs, which address the expected limitations on LHC performance imposed by the baseline insertions.
Date: May 29, 2003
Creator: al., James Strait et
Partner: UNT Libraries Government Documents Department

How the Performance of a Superconducting Magnet is affected by theConnection between a small cooler and the Magnet

Description: As low temperature cryocoolers become more frequently used to cool superconducting magnets, it becomes increasingly apparent that the connection between the cooler and the magnet has an effect on the design and performance of the magnet. In general, the use of small coolers can be considered in two different temperature ranges; (1) from 3.8 to 4.8 K for magnet fabricated with LTS conductor and (2) from 18 to 35 K for magnets fabricated using HTS conductor. In general, both temperature ranges call for the use of a two-stage cooler. The best method for connecting a cooler to the magnet depends on a number of factors. The factors include: (1) whether the cooler must be used to cool down the magnet from room temperature, (2) whether the magnet must have one or more reservoirs of liquid cryogen to keep the magnet cold during a loss of cooling, and (3) constraints on the distance from the cooler cold heads and the magnet and its shield. Two methods for connecting low temperature coolers to superconducting magnets have been studied. The first method uses a cold strap to connect the cold heads directly to the loads. This method is commonly used for cryogen-free magnets. The second method uses a thermal siphon and liquid cryogens to make the connection between the load being cooled and the cold head. The two methods of transferring heat from the magnet to the cooler low temperature cold head are compared for the two temperature ranges given above.
Date: September 8, 2005
Creator: Green, Michael A.
Partner: UNT Libraries Government Documents Department

Towards Integrated Design and Modeling of High Field Accelerator Magnets

Description: The next generation of superconducting accelerator magnets will most likely use a brittle conductor (such as Nb{sub 3}Sn), generate fields around 18 T, handle forces that are 3-4 times higher than in the present LHC dipoles, and store energy that starts to make accelerator magnets look like fusion magnets. To meet the challenge and reduce the complexity, magnet design will have to be more innovative and better integrated. The recent design of several high field superconducting magnets have now benefited from the integration between CAD (e.g. ProE), magnetic analysis tools (e.g. TOSCA) and structural analysis tools (e.g. ANSYS). Not only it is now possible to address complex issues such as stress in magnet ends, but the analysis can be better detailed an extended into new areas previously too difficult to address. Integrated thermal, electrical and structural analysis can be followed from assembly and cool-down through excitation and quench propagation. In this paper we report on the integrated design approach, discuss analysis results and point out areas of future interest.
Date: June 1, 2006
Creator: Caspi, S. & Ferracin, P.
Partner: UNT Libraries Government Documents Department

The Role of Quench-back in the Passive Quench Protection of Uncoupled Solenoids in Series with and without Coil Sub-division

Description: This paper is the final paper in a series of papers that discusses passive quench protection for high inductance solenoid magnets. This report describes how passive quench protection system may be applied to superconducting magnets that are connected in series but not inductively coupled. Previous papers have discussed the role of magnet sub-division and quench back from a conductive mandrel in reducing the hot-spot temperature and the peak coil voltages to ground. When magnets are connected in series, quench-back from a conductive mandrel can cause other magnets in a string to quench even without inductive coupling between magnets. The magnet mandrels must be well coupled to the magnet circuit that is being quenched. When magnet circuit sub-division is employed to reduce the voltages-to-ground within magnets, the resistance across the subdivision becomes the most important factor in the successful quenching of the magnet string.
Date: October 15, 2010
Creator: Guo, Xing Long; Green, Michael A; Wang, Li; Wu, Hong & Pan, Heng
Partner: UNT Libraries Government Documents Department

Fabrication and test results of a high field, Nb3Sn superconducting racetrack dipole magnet

Description: The LBNL Superconducting Magnet Program is extending accelerator magnet technology to the highest possible fields. A 1 meter long, racetrack dipole magnet, utilizing state-of-the-art Nb{sub 3}Sn superconductor, has been built and tested. A record dipole filed of 14.7 Tesla has been achieved. Relevant features of the final assembly and tested results are discussed.
Date: June 15, 2001
Creator: Benjegerdes, R.; Bish, P.; Byford, D.; Caspi, S.; Dietderich, D.R.; Gourlay, S.A. et al.
Partner: UNT Libraries Government Documents Department

TF Inner Leg Space Allocation for Pilot Plant Design Studies

Description: A critical design feature of any tokamak is the space taken up by the inner leg of the toroidal field (TF) coil. The radial build needed for the TF inner leg, along with shield thickness , size of the central solenoid and plasma minor radius set the major radius of the machine. The cost of the tokamak core roughly scales with the cube of the major radius. Small reductions in the TF build can have a big impact on the overall cost of the reactor. The cross section of the TF inner leg must structurally support the centering force and that portion of the vertical separating force that is not supported by the outer structures. In this paper, the TF inner leg equatorial plane cross sections are considered. Out-of- Plane (OOP) forces must also be supported, but these are largest away from the equatorial plane, in the inner upper and lower corners and outboard sections of the TF coil. OOP forces are taken by structures that are not closely coupled with the radial build of the central column at the equatorial plane. The "Vertical Access AT Pilot Plant" currently under consideration at PPPL is used as a starting point for the structural, field and current requirements. Other TF structural concepts are considered. Most are drawn from existing designs such as ITER's circular conduits in radial plates bearing on a heavy nose section, and TPX's square conduits in a case, Each of these concepts can rely on full wedging, or partial wedging. Vaulted TF coils are considered as are those with some component of bucking against a central solenoid or bucking post. With the expectation that the pilot plant will be a steady state machine, a static stress criteria is used for all the concepts. The coils are assumed to be ...
Date: September 6, 2012
Creator: Zolfaghari, Peter H. Titus and Ali
Partner: UNT Libraries Government Documents Department

High Field Magnet R&D in the USA

Description: Accelerator magnet technology is currently dominated by the use of NbTi superconductor. New and more demanding applications for superconducting accelerator magnets require the use of alternative materials. Several programs in the US are taking advantage of recent improvements in Nb{sub 3}Sn to develop high field magnets for new applications. Highlights and challenges of the US R and D program are presented along with the status of conductor development. In addition, a new R and D focus, the US LHC Accelerator Research Program, will be discussed.
Date: October 1, 2003
Creator: Gourlay, S.A.
Partner: UNT Libraries Government Documents Department

Passive temperature compensation in hybrid magnets with application to the Fermilab stacker and recycler ring dipole design

Description: Design theory of hybrid (permanent magnet plus iron) accelerator magnets with application to the proposed permanent magnet recycler and stacker rings at the Fermi National Laboratory is presented. Field stability in such devices requires that changes in the strength of the permanent magnet material with temperature be compensated. Field tuning techniques, including those employing variable capacitance between energized pole and magnet yoke and those employing variable energization of magnet pole pieces, are described. Mechanical configurations capable of achieving temperature compensation passively, including use of expanding liquids/gases and bimetallic springs are outlined. Active configurations, relying on a actuator, in addition to temperature compensation, have the additional benefit of enabling magnet tuning about a nominal operating field level.
Date: June 1, 1995
Creator: Schlueter, R.D.; Marks, S.; Loper, C. & Halbach, K.
Partner: UNT Libraries Government Documents Department

Design issues for cryogenic cooling of short periodsuperconducting undulators

Description: Superconducting insertion devices, which produce periodic magnetic fields, have been built and installed in a number of synchrotron-light source storage-rings. For the most part, these devices have been wigglers, which have relatively long period lengths. This report concerns itself with the special cryogenic issues associated with short period undulators. The motivation for considering the incorporation of superconducting technology in insertion device designs is to achieve higher magnetic fields than can be achieved with more conventional permanent magnet technology. Since the peak field decreases sharply with increased magnet gap to period ratio, the cryogenic design of the magnet system is crucial. In particular, the insulation required for a warm vacuum bore device is impractical for short period undulators. This report describes the issues that are related to a cold bore ({approx}4 K) and an intermediate temperature bore (30 to 70 K) designs. The criteria for the use of small cryocoolers for cooling a short period undulator are presented. The problems associated with connecting small coolers to an undulator at 4.2 K are discussed.
Date: September 15, 2003
Creator: Green, M.A.; Dietderich, D.R.; Marks, S.; Prestemon, S.O. & Schlueter, R.D.
Partner: UNT Libraries Government Documents Department


Description: The Visible-Infrared SASE Amplifier (VISA) FEL is an experimental device designed to show Self Amplified Spontaneous Emission (SASE) to saturation in the visible light energy range. It will generate a resonant wavelength output from 800--600 nm, so that silicon detectors may be used to characterize the optical properties of the FEL radiation. VISA is the first SASE FEL designed to reach saturation, and its diagnostics will provide important checks of theory. This paper includes a description of the VISA undulator, the magnet measuring and shimming system, and the alignment strategy. VISA will have a 4 m pure permanent magnet undulator comprising four 99 cm segments, each with 55 periods of 18 mm length. The undulator has distributed focusing built into it, to reduce the average beta function of the 70--85 MeV electron beam to about 30 cm. There are four FODO cells per segment. The permanent magnet focusing lattice consists of blocks mounted on either side of the electron beam, in the undulator gap. The most important undulator error parameter for a free electron laser is the trajectory walkoff or lack of overlap of the photon and electron beams. Using pulsed wire magnet measurements and magnet shimming, the authors expect to be able to control trajectory walkoff to less than {+-}50 pm per field gain length.
Date: August 16, 1998
Partner: UNT Libraries Government Documents Department

PEP-III magnet power conversion systems: Power supplies for large magnet strings

Description: This paper presents the cooperative design efforts of LBL, SLAC, and LLNL on the magnet power conversion systems for PEP-II. The systems include 900 channels of correction magnet bipolar supplies and 400 unipolar supplies in the range of 5 to 500 kW. We show the decision process and technical considerations influencing the choice of power supply technologies employed. We also show the development of specifications that take maximum advantage of both the resources available and existing facilities while at the same time satisfying tight constraints for cost control, scheduling and coordination of different working groups. Switch-mode power conversion techniques will be used extensively in these systems, from the corrector supplies to the largest units if the dynamic performance specifications demand it. General system descriptions for each of the power supply ranges and for a new common control system interface and regulator are included.
Date: May 1, 1995
Creator: Jackson, T.; Saab, A. & Shimer, D.
Partner: UNT Libraries Government Documents Department

Superconducting magnets, cryostats, and cryogenics for the interaction region of the SSC

Description: The Superconducting Super Collider (SSC) has two counterrotating 20-TeV proton beams that will be made to collide at specific interaction points to carry out high energy physics experiments. The Collider ring has two sites, West and East, for such Interaction Regions (IRs), and the conceptual design of the East Interaction Region is underway. The East IR, in the present stage of design, has two interaction points, the requirements for which have been specified in terms of distance L* to the nearest magnet and the beam luminosity. Based on these requirements, the optics for transition from arc regions or utility regions to the IR and for focusing the beams have been obtained. The optical arrangement consists of a tuning section of quadrupoles, the strength of which is adjusted to obtain the required beta squeeze; a pair of bending dipoles to reduce the beam separation from the nominal 900 mm to 450 mm; an achromat section of quadrupoles, which consist of two cold masses in one cryostat; another pair of dipoles to bring the beams together at the required crossing angle; and a set of final focus quads facing the interaction point. The optics is symmetric about the interaction point, and the two interaction points are separated by a hinge region consisting of superconducting dipoles and quadrupoles similar to the arc region. In the regions where the beams are vertically bent and straightened out by dipoles, the beam traverses warm regions provided for placing beam collimators. The superconducting magnets, including the final focus quadrupoles, operate with supercritical He at 4 atm and a nominal temperature of 4.15 K. In this paper, descriptions of the magnets, the cryostats, and cryo bypasses around the warm region and interaction points are provided. Also discussed are the cooling requirements and design for the final focus quadrupole, ...
Date: October 1, 1993
Creator: Jayakumar, R.J.; Abramovich, S. & Zhmad, A.
Partner: UNT Libraries Government Documents Department