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Induction core performance

Description: Large masses of magnetic core material are required for many of the induction accelerator-based projects currently under study; the quantities required exceed 10<sup>7</sup> kg for a linear heavy-ion fusion driver, so core performance and cost are critical issues. We have evaluated cores of amorphous alloys from AlliedSignal and MRTI (Moscow Radio Technical Institute) and nanocrystalline alloys from Hitachi and Vacuumschmelze. The cores were of moderate size, between 1 and 11 kg. We characterized the materials in terms of the flux swing {Delta}B from -B<sub>remanent</sub> to +B<sub>saturation</sub>, and the energy loss versus dB/dt. We found sources for each material that could coat, wind, and then anneal the cores. This required the development of thin coatings that withstand 350-550° C anneal temperatures. The result is core performance near the ultimate small sample performance of each material, with higher {Delta}B and lower losses than the earlier approaches of using as-cast material or rewinding after anneal, in both, cases usually cowinding with thin mylar (-4µm thick). We are beginning system code studies of tradeoffs between {Delta}B and losses.
Date: August 14, 1998
Creator: Faltens, A; Meier, W R; Molvik, A W; Reginato, L & Smith, C
Partner: UNT Libraries Government Documents Department

Direct drive and eddy-current septum magnets.

Description: Two types of thin septum magnets, direct drive and eddy current, were compared mainly in 2-D magnetic aspects. For the direct-drive type, the leakage field depended on the finite permeability of the magnet core and not on the thickness of the septum conductor. It was suggested that the leakage field be controlled by reducing the current in the septum conductor or by using a correction coil. There were no significant differences between the two types regarding thermal problems caused by high current densities in the thin septa. The leakage fields with 2-mm septum thicknesses were calculated using OPERA-2d to compare the two types. For the eddy-current type, the leakage fields calculated using OPERA-2d were compared with the calculations from Halbach's model. The leakage fields for the eddy-current type decayed with long time constants.
Date: September 13, 2001
Creator: Kim, S. H.
Partner: UNT Libraries Government Documents Department

A model for the magnetic cores of linear induction accelerator cells

Description: Linear induction cells are used in the electron beam accelerator for the proposed Dual Axis Radiographic Hydrotest (DARHT) facility that would be built at Los Alamos National Laboratory. Ferrite cores are used in each cell to produce 250 kV, flat to within {plus_minus}1% for 70 ns. In the course of operating a prototype test stand for the full accelerator, circuit models have been developed for the pulsed power system and the induction cells that have been useful in achieving the {plus_minus}1% flatness requirement. The circuit models use the MicroCap IV{trademark} electronic circuit analysis program, which includes a Jiles-Atherton model for magnetic materials. In addition, the coaxial, ferrite-filled geometry of the cell is modelled by a multiple-section lumped-element transmission line. Propagation of a voltage pulse through the ferrite cores, including saturation effects, can be reproduced. The model has been compared to actual waveforms obtained from prototype operations, and good results have been obtained for a wide range of operating conditions. Interest in possible future applications have led the authors to use the model to predict the behavior of accelerator cells driven by multiple voltage pulses without an intervening magnetic reset of the ferrite cores. Results show that multiple pulses can be applied to the accelerator cells without a magnetic reset, but with some degradation of later pulses. The degradation appears as a droop on the flat portion of the second (and subsequent) pulses. The droop can be corrected by shaping the waveform of the incident pulses.
Date: August 1, 1995
Creator: Melton, J.G. & Rose, E.A.
Partner: UNT Libraries Government Documents Department

Implications of a new induction core materials and coatings for high power induction accelerators

Description: Two recent developments enable induction accelerators to achieve better and more consistent performance with higher efficiency. First, better and more consistent performance is achieved with insulating coatings that allow magnetic cores to be annealed after winding. Second, losses are reduced by a factor of 2-3 with nanocrystalline alloys, while the flux swing is only slightly reduced to 2.0 T compared with 2.3 T with economical amorphous alloys. One metric for selecting between the alloys is the cost-of-electricity, COE. A systems code optimizes an accelerator and compares the COE for higher flux-swing amorphous and higher-efficiency nanocrystalline materials and for several variations in assumptions.
Date: April 9, 1999
Creator: Molvic, A W; Meier, W R; Moir, R W & Faltens, A
Partner: UNT Libraries Government Documents Department

Iron dominated resistive magnets

Description: This paper starts with a review of Amperes Law and Potential Theory (Perfect Iron). It then proceeds to a discussion of Magnet Ends and on to Curved Magnets, Coil Construction, and Core Construction. It concludes with a discussion of Quality Control Methods and Examples of Recent Magnets Built.
Date: June 3, 1999
Creator: Mills, Fred E.
Partner: UNT Libraries Government Documents Department

Fabrication techniques for septum magnets at the APS.

Description: The design, construction, and installation of pulsed septum magnets for particle accelerators presents many challenges for the magnet engineer. Issues associated with magnet core structure design, component alignment, weldment design, and electrical insulation choices are among those requiring careful attention. The designs of the six septum magnets required for the APS facility have evolved since operation began in 1996. Improvements in the designs have provided better injection/extraction performance parameters and extended the machine reliability to meet the requirements of a world-class, third-generation synchrotron radiation facility. Details of the techniques used to address issues involved in producing septum magnets at the APS are described here to aid magnet engineers in the fabrication of future septum magnets.
Date: September 16, 2002
Creator: Jaski, M.; Thompson, K.; Kim, S.; Friedsam, H.; Toter, W. & Humbert, J.
Partner: UNT Libraries Government Documents Department

Fast and reliable kicker magnets for the SLC damping rings

Description: The design, construction, and operation of a kicker magnet with superior electromagnetic performance and greatly improved radiation tolerance is described. A short flux return of high mu ferrite improves the field strength and linearity with current, and novel metallic field-confining structures minimize the inductance. An 8-cell structure with capacitance integrated into each cell makes the magnet a nearly perfect transmission line. The capacitor dielectric is 1 cm thick alumina-loaded epoxy, processed to eliminate air voids, and cast in a multiple step procedure developed to circumvent epoxy shrinkage. The magnet operates with pulses of up to 40 kV and 3.2 kA at 120 Hz, with magnet transit times of less than 35 nsec and field rise and fall times of less than 60 nsec.
Date: June 1, 1995
Creator: Mattison, T.S.; Cassel, R.L.; Donaldson, A.R. & Gross, G.
Partner: UNT Libraries Government Documents Department

A kicker design for the rapid transfer of the electron beam between radiator beamlines in LUX

Description: I present in this paper preliminary design concepts for a fast kicker magnet and driver for the rapid transfer of the electron beam between radiator beam lines in LUX. This paper presents a feasibility study to find a roughly optimized subset of engineering parameters that would satisfy the initial design specifications of: Pulse width &lt; 30 mu s, rise / fall time &lt; 10 mu s, time jitter &lt; 1ns, magnetic length &lt; 0.5meter, gap height = 15mm, gap width = 25mm, peak field = 0.6Tesla, bend angle = 1.7 deg. for beam energy of 3.1 Gev, repetition rate = 10KHz. An H magnet core configuration was chosen. Through an iterative mathematical process employing Mathcad 11 [1] a realizable design was chosen. Peak current, Peak voltage across the coils, conductor losses due to proximity and skin effects, and basic circuit topology were investigated. Types and losses of core material were only briefly discussed. The final topology consists of two magnets in series running at 10KHz, .3Tesla, 630 amp peak current, 10 mu s pulse width, 693 Watts per coil section, driven by fast solid state switch with an energy recovery inductor.
Date: June 30, 2004
Creator: Stover, Gregory D.
Partner: UNT Libraries Government Documents Department

Cold iron cos THETA magnet option for the SSC

Description: We review first the evolution over the past several years of a cold iron, high field cos THETA magnet design option for the SSC. We note the collaborative approach pursued by BNL and LBL on the 2-in-1 option, and the culmination of this effort in the tests of the BNL 4.5 m model magnets. Next, we discuss the subsequent 1-in-1 option being pursued jointly by BNL, Fermilab and LBL.
Date: January 1, 1985
Creator: Reardon, P.
Partner: UNT Libraries Government Documents Department

Single layer quadrupole design for SSC (Superconducting Super Collidar)

Description: The proposed Superconducting Super Collider (SSC) will require 1360 regular arc quadrupoles. This paper describes a single layer design for these magnets. This design is economically competitive with the more conventional two layer design and appears to be well suited to mass production because of its simplicity. The design uses 9 turns of Cu(NbTi) superconducting cable to produce an 155 Tesla/meter gradient at the 20 TeV peak energy. The systematic field harmonics are all better than the requirements. Detailed results of both magnetic and mechanical analyses are presented.
Date: January 1, 1987
Creator: Thompson, P.A.; Cottingham, J.; Dahl, P.; Garber, M.; Ghosh, A.; Goodzeit, C. et al.
Partner: UNT Libraries Government Documents Department

D0 Silicon Upgrade: Muon Shield Conceptual Design Report

Description: The nominal overall dimensions are 71-inch high x 71-inch wide x 144-inch long and has a 25-inch square hole throughout. The shield consists of three different materials, steel (inner most section), polycarbonate (central section) and lead (outer most section). The material thicknesses are, steel=15-inch, poly=6-inch and lead=2-inch. The estimated weight is {approx}69 tons. The shield is centered about the Tev beam line and the 25-inch square hole provides clearance to the low Beta quad, which is nominally 20-inch square. During beamline operation, the shield is in contact with Samus magnet core at the detector end and with the Main Ring shield wall on the MR side (with some small clearance {approx}2-inch-3-inch). The need for the clearance will be discussed later. The shield support structure consists steel structural members appropriately sized for loads encountered in the design. The structure must not only support the shield but, must be designed for rolling the entire assembly into position in the collision hall. It must provide for cylinders to lift the assembly, Hilman rollers and also connections for moving the entire assembly. The movement is considered to be similar to that with which the calorimeters were moved from the clean room to the sidewalk staging area, i.e. hydraulic cylinder and chain (see dwg. 3740.000-ME294017,3 sheets). This method will be used for the East to West motion and a hydraulic scheme will be used for any North-South motion. Since the shield is 144-inch long and the sidewalk structural support is {approx}96-inch, there is a section of the shield that is cantilevered (48-inch). Further, the EF toroid must open {approx}40+ inch for access to the detector during operations and this requires that the shield or some part of it must also move. This conceptual design suggests that the shield be designed in two pieces axially. These ...
Date: May 14, 1996
Creator: Stredde, Herman J.
Partner: UNT Libraries Government Documents Department

Pulsed ferrite core tests for 50-ns linear induction accelerator

Description: The Lawrence Livermore Laboratory undertook an investigation of the properties of ferrite materials to be used in a 5-MeV, 50-ns linear induction accelerator. The investigation, on a part-time basis, lasted about one year and had the cooperation and helpful suggestions of several manufacturers: TDK of Japan, Phillips of Holland, and Stackpole of the U.S.A. Ferrites have been widely used as tuning cavities for proton synchrotron accelerators at radio frequencies. In such an application, the ..mu..Qf factor is used in describing the figure of merit for ferrites where a high duty factor requires low loss ferrites. In a linear induction accelerator with an average reprate of 5-Hz, the ferrite losses are negligible and the concept of complex permeability in describing the losses will not be introduced, but a large signal ..delta..B/..delta..H will be used to describe their properties. The properties of interest in designing the accelerating cavity were (1) flux swing ..delta..B = B/sub r/ + B/sub m/ greater than 0.5T; (2) a residual flux density B/sub r/ greater than or = to 0.15T with a reset no greater than 2 Oer; (3) a relatively high incremental ..mu.. greater than 400 to keep the excitation current small in relation to the load current; and (4) a high resistivity for the 250-kV voltage hold-off.
Date: February 28, 1978
Creator: Reginato, L.; Cook, E.; Dexter, W. & Schmidt, J.
Partner: UNT Libraries Government Documents Department

Magnetic properties of the iron laminations for CBA magnets

Description: The required magnetic properties of the iron for CBA dipoles are for the most part the same as those for conventional accelerators, namely: low coercive force, high permeability at both low and high inductions, and high saturation induction. There are two main differences in the CBA application, (1) the iron is at 3.8/sup 0/K, and (2) the magnetic field in the iron can go as high as 6 Tesla, which is well above saturation. Measurements of the magnetization curves for CBA iron laminations at 300/sup 0/K and 4.2/sup 0/K are presented. The data are analyzed in terms of a simple model in which the variation in saturation induction can be separated from the low field permeability variation. Tolerances on coercive force, permeability, and saturation induction are discussed.
Date: January 1, 1983
Creator: Tannenbaum, M.J.; Ghosh, A.K.; Robins, K.E. & Sampson, W.B.
Partner: UNT Libraries Government Documents Department

Conceptual magnet design for an iron-free colliding beam accelerator

Description: Superconducting accelerator magnets usually have magnetic iron yokes to obtain maximum magnetic field and to limit stray field. However, the iron is expensive and heavy. The smaller size and weight of an iron-free magnet can result in lower magnet and refrigeration costs. However in a colliding beam accelerator the stray field from one ring produces aberrations in the field in the other. A way to eliminate this mutual interference is to surround each magnet with a coil that exactly cancels the field from the other ring magnet. That is expensive in terms of superconductor requirements. However, the cancellation of the external dipole field component is unnecessary. Only a small amount of superconductor is required for cancellation of the higher-order field-aberration components. Parameters for the iron-free magnet concept are investigated, and a preliminary conceptual design for an accelerator is presented.
Date: March 1, 1983
Creator: Taylor, C. & Meuser, R.B.
Partner: UNT Libraries Government Documents Department

Tevatron I: Large Bore Quad lamination analysis

Description: Stacking, compression, and welding of the laminations for the TeV I Large Bore Quad results in a deformation due to springback which is unacceptable due to magnetic field requirements. ANSYS has been used to analyze a solution to this problem.
Date: October 26, 1982
Creator: Leininger, M.
Partner: UNT Libraries Government Documents Department

Construction of a Fermilab superferric test magnet

Description: This technical memo documents the construction of a cold iron superconducting test magnet. The superferric magnet design was based on a concept sketch provided by Bob Wilson. Construction and dunk testing of the magnet in a liquid helium dewar took place in a time period of less than one week. The magnet operated successfully to its design field of 2 Tesla with no training.
Date: July 1, 1982
Creator: Heim, J.; Hinterberger, H. & Jagger, J.
Partner: UNT Libraries Government Documents Department

Performance testing of super Fe magnet

Description: A summary is given of the data obtained during the testing of a proof of principle iron-dominated low field and cost, high efficiency dipole. The magnet was tested for performance with the design field of 2.0T.
Date: June 30, 1982
Creator: McInturff, A.D.
Partner: UNT Libraries Government Documents Department

Pulser development for MBE-4

Description: The Multiple Beam Experiment MBE4 is designed to accelerate four cesium ion beams from 200 kV to about 1 MV using an induction linac and to demonstrate the process of current amplification simultaneously with acceleration. The injected beam is obtained from a source using a Marx generator providing typically 10 mA/beam with a length of 1.6 meters. This is equivalent to a beam duration time of about 3 ..mu..sec. Twenty four acceleration gaps in groups of four are distributed along the length of the machine which will be some 16 meters long when completed. Each group of four acceleration gaps with appropriate quadrupoles form one section of the machine, identified as A through F. Careful tailoring of the acceleration voltage waveforms at each gap is required to accelerate the beam, amplify the current and provide longitudinal focusing. Ideal voltage waveforms for each gap were generated for a gap voltage limit initially set at 30 kV. These waveforms are shown in Fig. 1. The waveforms for the first 4 gaps are triangular with an approximate width of 3 ..mu..sec, becoming flatter and shorter at subsequent gaps as the beam bunch velocity increases. Ninety two nickel-iron tape wound cores capable of 6.8 mVsec/core and twenty six silicon steel tape wound cores capable of 24 mVsec/core were available. Groups of cores at the first eight gaps have been used in conjunction with an appropriate number of pulsers to provide the necessary accelerating voltage waveforms together with the pulser waveforms at every fourth acceleration gap which provides the longitudinal focusing of the beam. This paper will deal with the performance of the pulsers for the first eight gaps of acceleration and expectations for the next four, currently under construction.
Date: June 1, 1986
Creator: Gough, D.E. & Brodzik, D.A.
Partner: UNT Libraries Government Documents Department

Reduction of iron saturation in cosine theta dipoles

Description: A procedure is presented for systematically perturbing the circular iron aperture of a cosine-theta dipole in such a way as to postpone saturation effects up to the point where insufficient iron is present on the midplane. The resulting configuration has little loss in field compared to the alternative procedure of putting a large annulus between the coils and the iron. The necessary saturable iron program used was MDP, but the procedure could be performed with any program. The perturbation functions used to modify the iron shape provide good separation of effects so that only one perturbation per harmonic is needed, thus minimizing the amount of computation required. A coil and aperture configuration with low-field harmonic content approaching the stringent RHIC requirements is presented which requires no b/sub 4/ or higher order correction coils up to 4.1 T, with a good field aperture at low field of 32 mm and at 4.1 T, 30 mm. The b/sub 2/ correction required is largest at an intermediate field, and has a maximum amplitude of about -3.2. The transfer function of the configuration is about 2% higher than that of the reference design.
Date: January 1, 1986
Creator: Morgan, G.
Partner: UNT Libraries Government Documents Department

Preliminary study of magnet design for an SSC

Description: The overriding design consideration for the SSC magnets is that cost of the facility be minimized; at 8 T, approximately 40 km of bending magnets is required for each ring of a 20 TeV collider. We present some results of a parametric study of two-in-one, iron-core magnets for an SSC. These results are necessarily preliminary in nature, and are intended only to show some of the trade-offs for a wide range of the variables. We show also some results for a reference design that produces 6.5 T in the aperture at 4.4 K for a coil inside diameter of 40 mm. It is not to be inferred that we have established this to be an optimum in any sense.
Date: August 1, 1983
Creator: Taylor, C.E. & Meuser, R.B.
Partner: UNT Libraries Government Documents Department

Superconducting magnet technology for accelerators

Description: A review article on superconducting magnets for accelerators should first answer the question, why superconductivity. The answer revolves around two pivotal facts: (1) fields in the range of 2 T to 10 T can be achieved; and (2) the operating cost can be less than conventional magnets. The relative importance of these two factors depends on the accelerator. In the case where an upgrade of an accelerator at an existing facility is planned, the ability to obtain fields higher than conventional magnets leads directly to an increase in machine energy for the given tunnel. In the case of a new facility, both factors must be balanced for the most economical machine. Ways to achieve this are discussed.
Date: March 1, 1984
Creator: Palmer, R. & Tollestrup, A.V.
Partner: UNT Libraries Government Documents Department

Finite-element stress and deflection analysis of CDF yoke and end plug

Description: A large detector is being designed to study anti pp collisions at center-of-mass energies of up to 2000 GeV as part of the Fermilab Collider Detector Facility (CDF). The central detector of this facility consists of a solenoid, calorimeter yoke, and a variety of particle measurement devices. The yoke will be a large steel structure that will provide the magnetic flux return path as well as support structure for calorimetry and other instrumentation. It must resist both electromagnetic and gravitational loads while exhibiting only small elastic deformations. The instrumented endplugs of the yoke are subjected to large electromagnetic loads. Moreover, due to the presence of wire chambers within these plugs, they must also be particularly stiff. The purpose of this paper is to present the results of a finite element stress and deflection analysis of these structures under various anticipated load conditions. The PATRAN-G finite element modeling program, installed on a CDF-VAX 11/780 and operating from a Ramtek 6212 colorgraphics terminal, was used to generate the analysis models. The actual finite element analysis was performed by the ANSYS general purpose finite element program, installed on the Fermilab Cyber 175's.
Date: May 24, 1982
Creator: Wands, R.; Grimson, J.; Kephart, R. & Theriot, D.
Partner: UNT Libraries Government Documents Department

Iron dominated magnets

Description: These two lectures on iron dominated magnets are meant for the student of accelerator science and contain general treatments of the subjects design and construction. The material is arranged in the categories: General Concepts and Cost Considerations, Profile Configuration and Harmonics, Magnetic Measurements, a few examples of ''special magnets'' and Materials and Practices. Extensive literature is provided.
Date: July 1, 1985
Creator: Fischer, G.E.
Partner: UNT Libraries Government Documents Department

First order study for an iron core OH system for TNS

Description: A simple comparison has been made between an air core and an iron core ohmic heating system for a particular device, and it was shown that the peak power requirements can be substantially reduced by the use of an iron core to power levels handled by industry today. It was also shown that for an ohmic heating system initiated plasma that the cost of the iron core ohmic heating power system (iron core, dual rectifier, and DC switch) is less than the cost for a subset of the power system for an air core system (dual rectifier and DC switch). There is considerable work being done on other methods of initiating the plasma none of which seem to be incompatible with the use of an iron core system.
Date: January 1, 1977
Creator: Ballou, J. K. & Schultz, J.
Partner: UNT Libraries Government Documents Department