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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

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

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

Development and test of the ITER SC conductor joints

Description: Joints for the ITER superconducting Central Solenoid should perform in rapidly varying magnetic field with low losses and low DC resistance. This paper describes the design of the ITER joint and presents its assembly process. Two joints were built and tested at the PTF facility at MIT. Test results are presented; losses in transverse and parallel field and the DC performance are discussed. The developed joint demonstrates sufficient margin for baseline ITRR operating scenarios.
Date: August 5, 1998
Creator: Gung, C. Y.; Jayakumar, R.; Manahan, R.; Martovetsky, N.; Michael, P.; Minervini, J. et al.
Partner: UNT Libraries Government Documents Department

Magnet coil electrical gaskets of high compliance and ampacity

Description: Coils employed in the magnets of the PHENIX Detector, presently under construction for RHIC (Relativistic Heavy Ion Collider) at the Brookhaven National Laboratory, are massive (weight {approximately} 8000 kG each). For that reason we subdivided them into a series of manageable subcoils that we will subsequent bolt together. Electrical terminals attached to the subcoils conductors are rigidly embedded and precisely located during vacuum impregnation. However; we anticipate some misalignment and nonuniform gaping to occur between terminals at assembly. We have elected to use electrical gaskets of compliance and ampacity between the bolted terminals to enhance the current carrying capability of the electrical joints. This paper describes the material candidates selected, the tests performed, and the relative ranking of the materials tested.
Date: May 17, 1995
Creator: Harvey, A.R. & Yamamoto, R.M.
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

The {open_quotes}INVERSE PROBLEM{close_quotes} to the evaluation of the magnetic fields

Description: In the design of superconducting magnet elements, such as may be required to guide and focus ions in a particle accelerator, one frequently premises some particular current distribution and then proceeds to compute the consequent magnetic field through use of the laws of Blot and Savart or of Ampere. When working in this manner one of course may need to revise frequently the postulated current distribution before arriving at a resulting magnetic field of acceptable field quality. It therefore is of interest to consider an alternative ({open_quotes}inverse{close_quotes}) procedure in which one specifies a desired character for the field required in the region interior to the winding and undertakes then to evaluate the current distribution on the specified winding surface that would provide this desired field. By evaluating the specified potential in the region interior to the winding along the interface, the authors have determined that a relaxation solution to the potential in the region outside the winding can be converged and used to calculate wire location. They have demonstrated this method by applying a slightly modified version of the program POISSON to a periodic alternating sinusoidal quadrupole field.
Date: June 1, 1995
Creator: Caspi, S.; Helm, M. & Laslett, L.J.
Partner: UNT Libraries Government Documents Department

Development of a high gradient magnetic separator using high temperature superconductors

Description: This is the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). High-gradient magnetic separation (HGMS) is an application of superconducting magnet technology to the process of magnetic separation of solids from other solids, liquids, or gases. The production of both high magnetic fields and large field gradients using superconducting magnet technology has made it possible to separate a previously unreachable but large family of paramagnetic materials. It is possible to separate more than half of the elements in the periodic table using this method. Because HGMS is a physical separation process, no additional or mixed waste is generated. This project sought to develop a high-gradient magnetic separator using a high-temperature superconducting magnet.
Date: September 1, 1996
Creator: Prenger, F.C.; Daney, D.; Daugherty, M. & Hill, D.
Partner: UNT Libraries Government Documents Department

TPX superconducting cable-in-conduit 1995 design and development progress

Description: A unique feature of the magnet system for the Tokamak Physics Experiment (TPX) is that all the magnets are superconducting. With the exception of the outer poloidal coils, the magnet system uses Nb{sub 3}Sn cable-in-conduit conductor; the outer poloidal coils use Nb-Ti cable-in-conduit conductor. We describe the current TPX conductor design and present a progress report on the conductor development. Our strand development contracts have resulted in demonstrating that at least two vendors can produce Nb{sub 3}Sn strand which meets the TPX specification. Subcable testing gives confidence that the TPX conductor will satisfy the magnet operational requirements. Fabrication of full-size conductors is underway and tests on these will give verification that the TPX conductor meets the operational requirements. Our industrial cabling and sheathing contract to produce demonstration conductor using copper strands is exploring a production technique that differs from the conventional tube mill approach.
Date: September 29, 1995
Creator: Zbasnik, J. P.; Martovetsky, N. N. & Hibbs, S. M.
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

The muon g-2 storage ring magnet

Description: The muon g-2 experiment at Brookhaven National Laboratory has constructed a 7.112m radius superconducting magnet. The design and construction of the storage ring magnet are described.
Date: July 1, 1998
Creator: Lee, Y.Y.; Addessi, L. & Armoza, Z.
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

Cryogenic tests of the g-2 superconducting solenoid magnet system

Description: The g-2 muon storage ring magnet system consists of four large superconducting solenoids that are up to 15.1 m in diameter. The g-2 superconducting solenoids and a superconducting inflector dipole will be cooled using forced two-phase helium in tubes. The forced two-phase helium cooling will be provided from the J-T circuit of a refrigerator that is capable of delivering 625 W at 4.5 K. The two-phase helium flows from the refrigerator J-T circuit through a heat exchanger in a storage dewar that acts as a phase separator for helium returning from the magnets. The use of a heat exchanger in the storage dewar reduces the pressure drop in the magnet flow circuit, eliminates most two phase flow oscillations, and it permits the magnets to operate at variable thermal loads using the liquid in the storage dewar as a buffer. The g-2 magnet cooling system will consist of three parallel two-phase helium flow circuits that provide cooling to the following components: (1) the four large superconducting solenoids, (2) the current interconnects between the solenoids and the solenoid gas cooled electrical leads, and (3) the inflector dipole and its gas cooled electrical leads. This report describes a cryogenic test of the two 15.1 meter diameter superconducting solenoids using two-phase helium from a dewar. The report describes the cool down procedure for the 3.5 ton outer solenoid magnet system using liquid nitrogen and two-phase helium. Low current operation of the outer solenoids is discussed.
Date: August 1995
Creator: Jia, L. X.; Cullen, J. R. ,Jr. & Esper, A. J.
Partner: UNT Libraries Government Documents Department

Processing and properties of Ag-clad BSCCO superconductors

Description: Long lengths of mono- and multifilament Ag-clad BSCCO (Bi-Sr-Ca-Cu-O) conductors with critical current densities of >10{sup 4} A/cm{sup 2} at 77 K were fabricated by the powder-in-tube method. {Tc} magnets were assembled by stacking pancake coils fabricated from long tapes and then tested vs applied magnetic field at various temperatures. A magnet that contained {approx}2400 m of {Tc} conductor generated a field of 3.2 T at 4.2 K. In-situ tensile and bending properties of the Ag-clad conductors were studied. Multilayer Ag/superconductor composites were fabricated by chemical etching. Preliminary results with multilayer tapes show that continuous Ag reinforcement of the BSCCO core improves strain tolerance of the tapes so they can carry 90% of their initial I{sub c} at 1% bend strain desite a higher superconductor/Ag ratio than that of unreinforced tapes.
Date: March 1, 1996
Creator: Jammy, R.; Iyer, A.N.; Chudzik, M.; Balachandran, U. & Haldar, P.
Partner: UNT Libraries Government Documents Department

Overview of linac applications at future radioactive beam facilities

Description: There is considerable interest worldwide in the research which could be done at a next generation, advanced radioactive beam facility. To generate high quality, intense beams of accelerated radionuclides via the {open_quotes}isotope separator on-line{close_quotes} (ISOL) method requires two major accelerator components: a high power (100 kW) driver device to produce radionuclides in a production target/ion source complex, and a secondary beam accelerator to produce beams of radioactive ions up to energies on the order of 10 MeV per nucleon over a broad mass range. In reviewing the technological challenges of such a facility, several types of modem linear accelerators appear well suited. This paper reviews the properties of the linacs currently under construction and those proposed for future facilities for use either as the driver device or the radioactive beam post-accelerator. Other choices of accelerators, such as cyclotrons, for either the driver or secondary beam devices of a radioactive beam complex will also be compared. Issues to be addressed for the production accelerator include the choice of ion beam types to be used for cost-effective production of radionuclides. For the post-accelerator the choice of ion source technology is critical and dictates the charge-to-mass requirements at the injection stage.
Date: November 1, 1996
Creator: Nolen, J.A.
Partner: UNT Libraries Government Documents Department

The cryogenics of the LHC interaction region final focus superconducting magnets

Description: The LHC interaction region final focus magnets will include four superconducting quadrupoles cooled with pressurized, static superfluid helium at 1.9 K. The heat absorbed in pressurized He II, which may be more than 10 Watts per meter due to dynamic heating from the particle beam halo, will be transported to saturated He II at 1.8 K and removed by the 16 mbar vapor. This paper discusses the conceptual design for the cryogenics of the interaction region final focus superconducting magnets and the integration of this magnet system into the overall LHC cryogenic system.
Date: August 1, 1998
Creator: Byrns, R. & et al., FNAL
Partner: UNT Libraries Government Documents Department