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Thermal, Electrical and Mechanical Response to a Quench in Nb3Sn Superconducting Coils

Description: During a quench, significant temperatures can arise as a magnet's stored energy is dissipated in the normal zone. Temperature gradients during this process give rise to localized strains within the coil. Reactive forces in the magnet structure balance the electromagnetic and thermal forces and maintain on equilibrium. In this paper we present a complete 3D finite element analysis of a racetrack coil. Specifically, the analysis focuses on thermal, electrical and mechanical conditions in a 10T Nb{sub 3}Sn coil built and tested as part of LBNL's Subscale Magnet Program. The study attempts to simulate time history of the temperature and voltage rise during quench propagation. The transient thermal stress after the quench is then evaluated and discussed.
Date: October 1, 2003
Creator: Ferracin, P.; Caspi, S.; Chiesa, L.; Gourlay, S.A.; Hafalia, R.r.; Imbasciati, L. et al.
Partner: UNT Libraries Government Documents Department

Forces and Stored Energy in Thin Cosine (n0) Accelerator Magnets

Description: We wish to compute Lorentz forces, equilibrium stress and stored energy in thin multipole magnets (Fig.1), that are proportional to cos(n{theta}) and whose strength varies purely as a Fourier sinusoidal series of the longitudinal coordinate z (say proportional to cos (2m-1){pi}z/L where L denotes the half-period and m = 1,2,3...). We shall demonstrate that in cases where the current is situated on such a surface of discontinuity at r = R (i.e. J = f({theta},z)), by computing the Lorentz force and solving the state of equilibrium on that surface, a closed form solution can be obtained for single function magnets as well as for any combination of interacting nested multi function magnets. The results that have been obtained, indicate that the total axial force on the end of a single multipole magnet n is independent (orthogonal) to any other multipole magnet i as long as n {ne} i. The same is true for the stored energy, the total energy of a nested set of multipole magnets is equal to the some of the energy of the individual magnets (of the same period length 2L). Finally we demonstrate our results on a nested set of magnets a dipole (n = 1) and a quadmpole (n=2) that have an identical single periodicity {omega}{sub 1}. We show that in the limiting 2D case (period 2L tends to infinity), the force reduces to the commonly known 2D case.
Date: March 18, 1996
Creator: Caspi, S.
Partner: UNT Libraries Government Documents Department

Considerations Against a Force Compensated Coil

Description: The cost of structural components in a large superconducting coil may well exceed the coil and cryostat cost. As a result, the idea of constructing a system composed of two different coil types assembled in such a way that the forces balance and reduce the total structural requirement is oft proposed. A suitable geometry has never been found for the fundamental reason that there can be no force compensated solution. In this paper, the general problem is presented and an analysis of the energy stored and stresses produced in the structure are described in a fundamental way. Finally, the relation between structural mass M and stored energy E, M {ge} {rho}E/{sigma}{sub w}, that is valid for all, magnetic systems is developed, where {rho} is the density of the structure and {sigma}{sub w} is the working stress in the structure.
Date: August 1, 1988
Creator: Hassenzahl, W.
Partner: UNT Libraries Government Documents Department

The 3D Vector Potential, Magnetic Field and Stored Energy in a Thin cos2 theta Coil Array

Description: The vector potential and the magnetic field have been derived for an arrays of quadrupole magnets with thin Cos(2{theta}) current sheet placed at r = R.{sup bc}. The field strength of each coil within the array, varies purely as a Fourier sinusoidal series of the longidutinal coordinate z in proportion to {omega}{sub m}z, where {omega}{sub m} = (2m-1){pi}/L, L denotes the half-period, and m = 1,2,3 etc. The analysis is based on the expansion of the vector potential in the region external to the windings of a linear 3D quad, and a revision of that expansion by the application of the 'Addition Theorem' from that around the coil center to that around any arbitrary point in space.
Date: July 9, 1997
Creator: Caspi, S.
Partner: UNT Libraries Government Documents Department

Graded High Field Nb3Sn Dipole Magnets

Description: Dipole magnets with fields beyond 16T will require superconducting coils that are at least 40 mm thick, an applied pres-stress around 150 MPa and a protection scheme for stored energy in the range of 1-2 MJ/m. The coil size will have a direct impact on the overall magnet cost and the stored energy will raise new questions on protection. To reduce coil size and minimize risk, the coil may have to be graded. Grading is achieved by splitting the coil into several layers with current densities that match the short sample field in each layer. Grading, especially at high fields, can be effective; however it will also significantly raise the stress. In this paper we report on the results of a study on the coil size and field relation to that of the stress and stored energy. We then extend the results to graded coils and attempt to address high stress issues and ways to reduce it.
Date: June 1, 2007
Creator: Caspi, S.; Ferracin, P. & Gourlay, S.
Partner: UNT Libraries Government Documents Department

The Mechanical and Thermal Design for the MICE Detector SolenoidMagnet System

Description: The detector solenoid for MICE surrounds a scintillating fiber tracker that is used to analyze the muon beam within the detector. There are two detector magnets for measuring the beam emittance entering and leaving the cooling channel that forms the central part of the experiment. The field in the region of the fiber detectors must be from 2.8 to 4 T and uniform to better than 1 percent over a volume that is 300 mm in diameter by 1000 mm long. The portion of the detector magnet that is around the uniform field section of the magnet consists of two short end coils and a long center coil. In addition, in the direction of the MICE cooling channel, there are two additional coils that are used to match the muon beam in the cooling channel to the beam required for the detectors. Each detector magnet module, with its five coils, will have a design stored-energy of about 4 MJ. Each detector magnet is designed to be cooled using three 1.5 W coolers. This report presents the mechanical and electrical parameters for the detector magnet system.
Date: September 26, 2004
Creator: Fabbricatore, P.; Farinon, S.; Perrella, M.; Bravar, U. & Green,M.A.
Partner: UNT Libraries Government Documents Department

Thermal, Electrical and Mechanical Response to a Quench in Nb3SnSuperconducting Coils

Description: During a quench, significant temperatures can arise as a magnet's stored energy is dissipated in the normal zone. Temperature gradients during this process give rise to localized strains within the coil. Reactive forces in the magnet structure balance the electromagnetic and thermal forces and maintain on equilibrium. In this paper we present a complete 3D finite element analysis of a racetrack coil. Specifically, the analysis focuses on thermal, electrical and mechanical conditions in a 10 T Nb{sub 3}Sn coil built and tested as part of LBNL's Subscale Magnet Program. The study attempts to simulate time history of the temperature and voltage rise during quench propagation. The transient thermal stress after the quench is then evaluated and discussed.
Date: November 10, 2003
Creator: Ferracin, F.; Caspi, S.; Chiesa, L.; Gourlay, S.A.; Hafalia,R.R.; Imbasciati, L. et al.
Partner: UNT Libraries Government Documents Department

The Cost of Superconducting Magnets as a Function of Stored Energy and Design Magnetic Induction Times the Field Volume

Description: By various theorems one can relate the capital cost of superconducting magnets to the magnetic energy stored within that magnet. This is particularly true for magnet where the cost is dominated by the structure needed to carry the magnetic forces. One can also relate the cost of the magnet to the product of the magnetic induction and the field volume. The relationship used to estimate the cost the magnet is a function of the type of magnet it is. This paper updates the cost functions given in two papers that were published in the early 1990 s. The costs (escalated to 2007 dollars) of large numbers of LTS magnets are plotted against stored energy and magnetic field time field volume. Escalated costs for magnets built since the early 1990 s are added to the plots.
Date: August 27, 2007
Creator: Green, Mike; Green, M.A. & Strauss, B.P.
Partner: UNT Libraries Government Documents Department

Vector Potential and Stored Energy of a Quadrupole Magnet Array

Description: The vector potential, magnetic field and stored energy of a quadrupole magnet array are derived. Each magnet within the array is a current sheet with a current density proportional to the azimuthal angle 2{theta} and the longitudinal periodicity (2m-1){pi}/L. Individual quadrupoles within the array are oriented in a way that maximizes the field gradient The array does not have to be of equal spacing and can be of a finite size, however when the array is equally spaced and is of infinite size the solution can be simplified. We note that whereas, in a single quadrupole magnet with a current density proportional to cos2{theta} the gradient is pure, such purity is not preserved in a quadrupole array.
Date: March 15, 1999
Creator: Caspi, S.
Partner: UNT Libraries Government Documents Department

Estimating the Cost of Superconducting Magnets and the Refrigerators Needed to Keep Them Cold

Description: The cost of superconducting magnets and the refrigerators needed to keep them cold can be estimated if one knows the magnet stored energy and the amount of refrigeration needed. This report updates the cost data collected over 20 years ago by Strobridge and others. Early cost data has been inflated into 1991 dollars and data on newer superconducting magnets has been added to the old data. The cost of superconducting magnets has been correlated with stored energy and field-magnetic volume product. The cost of the helium refrigerator cold box and the compressors needed to keep the magnet cold can be correlated with the refrigeration generated at 4.5K. The annual cost of 4.5K refrigeration can be correlated with 4.5K refrigeration and electrical energy cost.
Date: June 1, 1991
Creator: Green, M. A.; Byrns, R. & St. Lorant, S. J.
Partner: UNT Libraries Government Documents Department

Data Relating to Hanford Mined Graphite (2273-D) Samples Annealed at NAA

Description: On 2/8/1950, there was mined from process tube 2273 in D pile at Hanford a quantity of graphite power, which was expected to show the most extensive radiation damage of any graphite available at that time. A series of samples of this powder were annealed in 100 degrees increments from 100 degrees to 2000 degrees C at this labaoratory. There were returned to Hanford and shipped by them to the National Bureau of Standards for total stored energy measurements. The present memorandum is comprised of a description of the annealing procedure used here, curves giving the detailed annealing history of each sample, and various curves derived from data obtained from these samples at Hanford and at the National Bureau of Standards.
Date: March 15, 1951
Creator: Smith, C.A. & Carter, R.L.
Partner: UNT Libraries Government Documents Department

Mechanical Behavior Analysis of a Test Coil for MICE Coupling Solenoid during Quench

Description: The coupling magnet for the Muon Ionization Cooling Experiment has a self-inductance of 592 H and the magnet stored energy of 13 MJ at a full current of 210 A for the worst operation case of the MICE channel. The high level of stored energy in the magnet can cause high peak temperature during a quench and induce considerable impact of stresses. One test coil was built in order to validate the design method and to practice the stress and strain situation to occur in the coupling coil. In this study, the analysis on stress redistribution during a quench with sub-divided winding was performed. The stress variation may bring about failure of impregnating material such as epoxy resin, which is the curse of a new normal zone arising. Spring models for impregnating epoxy and fiber-glass cloth in the coil were used to evaluate the mechanical disturbance by impregnated materials failure. This paper presents the detailed dynamic stress and stability analysis to assess the stress distribution during the quench process and to check whether the transient loads are acceptable for the magnet.
Date: October 28, 2009
Creator: Pan, Heng; Wang, Li; Guo, Xinglong; Wu, Hong & Green, M.A.
Partner: UNT Libraries Government Documents Department

Accelerator physics and technology limitations to ultimate energy and luminosity in very large hadron colliders

Description: The following presents a study of the accelerator physics and technology limitations to ultimate energy and luminosity in very large hadron colliders (VLHCs). The main accelerator physics limitations to ultimate energy and luminosity in future energy frontier hadron colliders are synchrotron radiation (SR) power, proton-collision debris power in the interaction regions (IR), number of events-per-crossing, stored energy per beam and beam-stability [1]. Quantitative estimates of these limits were made and translated into scaling laws that could be inscribed into the particle energy versus machine size plane to delimit the boundaries for possible VLHCs. Eventually, accelerator simulations were performed to obtain the maximum achievable luminosities within these boundaries. Although this study aimed at investigating a general VLHC, it was unavoidable to refer in some instances to the recently studied, [2], 200 TeV center-of-mass energy VLHC stage-2 design (VLHC-2). A more thorough rendering of this work can be found in [3].
Date: December 5, 2002
Creator: al., P. Bauer et
Partner: UNT Libraries Government Documents Department

Effect of thermo-mechanical stress during quench on Nb3Sn cable performance

Description: Several high field magnets using Nb{sub 3}Sn superconductor are under development for future particle accelerators. The high levels of stored energy in these magnets can cause high peak temperatures during a quench. The thermomechanical stress generated in the winding during the fast temperature rise can result in a permanent damage of the brittle Nb{sub 3}Sn. Although there are several studies of the critical current degradation of Nb{sub 3}Sn strands due to strain, little is known about how to apply the strain limitations to define a maximum acceptable temperature in the coils during a quench. Therefore, an experimental program was launched, aimed at improving the understanding of the effect of thermo-mechanical stress in coils made from brittle Nb{sub 3}Sn. A first experiment, reported here, was performed on cables. The experimental results were compared to analytical and finite element models. The next step in the experimental program will be to repeat similar measurements in small racetrack coils and later in full size magnets.
Date: December 9, 2002
Creator: al., Linda Imbasciati et
Partner: UNT Libraries Government Documents Department

Overview of the Initial NSTX Experimental Results

Description: The main aim of the National Spherical Torus Experiment (NSTX) is to establish the fusion physics principles of the spherical torus (ST) concept. The NSTX device began plasma operations in February 1999 and the plasma current Ip was successfully brought up to the design value of 1 million amperes on December 14, 1999. The planned plasma shaping parameters, k = 1.6 {+-} 2.2 and d = 0.2 {+-} 0.4, were achieved in inner limited, single null and double null configurations. The CHI (Coaxial Helicity Injection) and HHFW (High Harmonic Fast Wave) experiments were also initiated. A CHI injected current of 27 kA produced up to 260 kA of toroidal current without using an ohmic solenoid. With an injection of 2.3 MW of HHFW power, using twelve antennas connected to six transmitters, electrons were heated from a central temperature of 400 eV to 900 eV at a centraldensity of 3.5 x 1013 cm-3 increasing the plasma energy to 59 kJ and the toroidal beta, bT to 10 %. Finally, the NBI system commenced operatio n in Sept. 2000. The initial results with two ion sources (PNBI = 2.8 MW) shows good heating, producing a total plasma stored energy of 90 kJ corresponding to bT = 18 % at a plasma current of 1.1 MA
Date: November 16, 2000
Creator: Ono, M.; Bell, M.; Bell, R. E.; Bigelow, T.; Bitter, M. & al, et
Partner: UNT Libraries Government Documents Department

LAUNCHER PERFORMANCE AND THERMAL CAPABILITY OF THE DIII-D ECH SYSTEM

Description: OAK-B135 The temperatures of components of DIII-D ECH launchers were observed during 2003 tokamak operation. The injected power was typically 500-700 kW and the pulse length was typically 2s. Plasma shots were performed at intervals of about 17 min from 9 a.m. to 5 p.m. The temperatures of a movable mirror, a fixed mirror and a launcher reached an equilibrium after about six hours of repetitive pulsing. The saturation temperature depends to some extent on the plasma stored energy. However, even in high {beta} plasma, the temperatures plateaued at acceptable values.
Date: October 1, 2003
Creator: KAJIWARA,K; LOHR,J; GORELOV,I.A; GREEN,M.T; PONCE,D; CALLIS,R.W et al.
Partner: UNT Libraries Government Documents Department

Recent Progress on the National Spherical Torus Experiment (NSTX)

Description: Recent upgrades to the NSTX facility have led to improved plasma performance. Using 5MW of neutral beam injection, plasmas with toroidal {beta}{sub T} (= 2{micro}{sub 0}<p>/B{sub T}{sup 2} where B{sub T} is the vacuum toroidal field at the plasma geometric center) > 30% have been achieved with normalized {beta}{sub N} (= {beta}{sub T}aB{sub I}/I{sub p}) {approx} 6% {center_dot} m {center_dot} T/MA.. The highest {beta} discharge exceeded the calculated no-wall {beta} limit for several wall times. The stored energy has reached 390kJ at higher toroidal field (0.55T) corresponding to {beta}{sub T} {approx} 20% and {beta}{sub N} = 5.4. Long pulse ({approx}1s) high {beta}{sub p} ({approx}1.5) discharges have also been obtained at higher {beta}{sub {phi}} (0.5T) with up to 6MW NBI power. The highest energy confinement times, up to 120ms, were observed during H-mode operation which is now routine. Confinement times of {approx}1.5 times ITER98pby2 for several {tau}{sub E} are observed during both H-Mode and non-H-Mode discharges. Calculations indicate that many NSTX discharges have very good ion confinement, approaching neoclassical levels. High Harmonic Fast Wave current drive has been demonstrated by comparing discharges with waves launched parallel and anti-parallel to the plasma current.
Date: July 2, 2002
Creator: Gates, D. A.; Bell, M. G.; Bell, R. E.; Bialek, J.; Bigelow, T.; Bitter, M. et al.
Partner: UNT Libraries Government Documents Department

CONCEPTUAL DESIGN STUDY OF HORN POWER SUPPLY.

Description: A 250 kA pulsed power supply is required for the focusing horn of the proposed Brookhaven AGS Super Neutrino Beam Facility for long baseline neutrino oscillation experiment. It is expected to pulse at 2.5 Hz repetition rate. A preliminary study is being conducted to explore the key issues associated with the power supply system design. Advanced technologies used in similar systems as well as new ideas are being examined, simulated and evaluated. This power supply will be a very high stored energy, high average power, and high peak power system.
Date: June 16, 2003
Creator: ZHANG,W.; SANDBERG,J. & WENG,W.T.
Partner: UNT Libraries Government Documents Department

The Mechanical and Thermal Design for the MICE Coupling SolenoidMagnet

Description: The MICE coupling solenoids surround the RF cavities that are used to increase the longitudinal momentum of the muon beam that is being cooled within MICE. The coupling solenoids will have a warm-bore diameter of 1394 mm. This is the warm bore that is around the 200 MHz RF cavities. The coupling solenoid is a single superconducting coil fabricated from a copper matrix Nb-Ti conductor originally designed for MRI magnets. A single coupling magnet is designed so that it can be cooled with a single 1.5 W (at 4.2 K) cooler. The MICE cooling channel has two of these solenoids, which will be hooked together in series, for a magnet circuit with a total stored-energy of the order of 12.8 MJ. Quench protection for the coupling coils is discussed. This report also presents the mechanical and thermal design parameters for this magnet, including the results of finite element calculations of mechanical forces and heat flow in the magnet cold mass.
Date: September 20, 2004
Creator: Green, M.A.; Yang, S.Q.; Bravar, U.; Lau, W.; Li, D.; Strauss,B.P. et al.
Partner: UNT Libraries Government Documents Department

Design and Construction of Test Coils for the MICE Coupling Solenoid Magnet

Description: The superconducting coupling solenoid to be applied in the Muon Ionization Cooling Experiment (MICE) is made from copper matrix Nb-Ti conductors with inner radius of 750 mm, length of 285 mm and thickness of 102.5 mm at room temperature. The magnetic field up to 2.6 T at the magnet centerline is to keep the muons within the MICE RF cavities. Its self inductance is around 592 H and its magnet stored energy is about 13 MJ at a full current of 210 A for the worst operation case of the MICE channel. The stress induced inside the coil during cool down and charging is relatively high. Two test coils are to build and test in order to validate the design method and develop the fabrication technique required for the coupling coil winding, one is 350 mm inner diameter and full length same as the coupling coil, and the other is one-quarter length and 1.5 m diameter. The 1.5 m diameter coil will be charged to strain conditions that are greater than would be encountered in the coupling coil. This paper presents detailed design of the test coils as well as developed winding skills. The analyses on stress in coil assemblies, AC loss, and quench process are carried out.
Date: August 8, 2008
Creator: Wang, Li; Pan, Heng; Xu, F.Y.; Liu, XioaKun; Chen, AnBin; Li, LanKai et al.
Partner: UNT Libraries Government Documents Department

Lessons from Iowa : development of a 270 megawatt compressed air energy storage project in midwest Independent System Operator : a study for the DOE Energy Storage Systems Program.

Description: The Iowa Stored Energy Park was an innovative, 270 Megawatt, $400 million compressed air energy storage (CAES) project proposed for in-service near Des Moines, Iowa, in 2015. After eight years in development the project was terminated because of site geological limitations. However, much was learned in the development process regarding what it takes to do a utility-scale, bulk energy storage facility and coordinate it with regional renewable wind energy resources in an Independent System Operator (ISO) marketplace. Lessons include the costs and long-term economics of a CAES facility compared to conventional natural gas-fired generation alternatives; market, legislative, and contract issues related to enabling energy storage in an ISO market; the importance of due diligence in project management; and community relations and marketing for siting of large energy projects. Although many of the lessons relate to CAES applications in particular, most of the lessons learned are independent of site location or geology, or even the particular energy storage technology involved.
Date: January 1, 2012
Creator: Holst, Kent (Iowa Stored Energy Plant Agency, Traer, IA); Huff, Georgianne; Schulte, Robert H. (Schulte Associates LLC, Northfield, MN) & Critelli, Nicholas (Critelli Law Office PC, Des Moines, IA)
Partner: UNT Libraries Government Documents Department

STATUS OF THE NIF POWER CONDITIONING SYSTEM

Description: The NIF Power Conditioning System provides the pulsed excitation required to drive flashlamps in the laser's optical amplifiers. Modular in design, each of the 192 Main Energy Storage Modules (MESMs) storage up to 2.2 MJ of electrical energy in its capacitor bank before delivering the energy to 20 pairs of flashlamps in a 400 {micro}s pulse (10% power points). The peak current of each MESM discharge is 0.5 MA. Production, installation, commissioning and operation of the NIF Power Conditioning continue to progress rapidly, with the goals of completing accelerated production in late 2007 and finishing commissioning by early 2008, all the while maintaining an aggressive operations schedule. To date, more than 80% of the required modules have been assembled, shipped and installed in the facility, representing more that 240 MJ of stored energy available for driving NIF flashlamps. The MESMs have displayed outstanding reliability during daily, multiple-shift operations.
Date: July 26, 2007
Creator: Arnold, P; Hulsey, S; Ullery, G; Petersen, D; Pendleton, D; Ollis, C et al.
Partner: UNT Libraries Government Documents Department

Recent progress on the National Spherical Torus Experiment (NSTX)

Description: Recent upgrades to the NSTX facility have led to improved plasma performance. Using 5MW of neutral beam injection, plasmas with toroidal {beta}{sub T} (= 2{mu}{sub 0}<p>/B{sub T}{sup 2} where B{sub T} is the vacuum toroidal field at the plasma geometric center) > 30% have been achieved with normalized {beta}{sub N} (={beta}{sub T}aB{sub I}/I{sub p}) {approx} 6% {center_dot} m {center_dot} T/MA. The highest {beta} discharge exceeded the calculated no-wall {beta} limit for several wall times. The stored energy has reached 390kJ at higher toroidal field (0.55T) corresponding to {beta}{sub T} {approx} 20% and {beta}{sub N} = 5.4. Long pulse ({approx}1s) high {beta}{sub p} ({approx}1.5) discharges have also been obtained at higher B{sub {phi}} (0.5T) with up to 6MW NBI power. The highest energy confinement times, up to 120ms, were observed during H-mode operation which is now routine. Confinement times of {approx} 1.5 times ITER98pby2 for several {tau}{sub E} are observed during both H-Mode and non-H-Mode discharges. Calculations indicate that many NSTX discharges have very good ion confinement, approaching neoclassical levels. High Harmonic Fast Wave current drive has been demonstrated by comparing discharges with waves launched parallel and anti-parallel to the plasma current.
Date: January 1, 2002
Creator: Maqueda, R. J. (Ricardo J.); Wurden, G. A. (Glen A.); Gates, D. A.; Bell, M. G.; Bialek, J.; Bigelow, T. et al.
Partner: UNT Libraries Government Documents Department

Instrumentation and Quench Protection for LARP Nb3Sn Magnets

Description: The US LHC Accelerator Research Program (LARP) is developing Nb{sub 3}Sn prototype quadrupoles for the LHC interaction region upgrades. Several magnets have been tested within this program and understanding of their behavior and performance is a primary goal. The instrumentation is consequently a key consideration, as is protection of the magnet during quenches. In all LARP magnets, the flexible circuits traces combine the instrumentation and the protection heaters. Their fabrication relies on printed circuit technology based on a laminate made of a 45-micron thick kapton sheet and a 25-micron thick foil of stainless steel. This paper reviews the protection heaters designs used in the TQ (Technology Quadrupole) and LR (Long Racetrack) series as well as the one used in LBNL HD2a high field dipole and presents the design of the traces for the Long Quadrupole (LQ), addressing challenges associated with the stored energy and the length of the magnet.
Date: August 17, 2008
Creator: Felice, H.; Ambrosio, G.; Chlachidize, G.; Ferracin, P.; Hafalia, R.; Hannaford, R. C. et al.
Partner: UNT Libraries Government Documents Department