Design Of Accelerator Magnets Research Articles

Model-Based System Engineering Framework for Superconducting Accelerator Magnet Design

The design specification of future high-field accelerator magnets require innovation in and integration of multiple disciplines. Numerical models underpin each step of the design. In this paper, we present a methodology for collaborative modeling based on relevant concepts of model-based systems engineering. The methodology is composed of three pillars: encapsulated computing environments with service query interface, model notebooks with auto-generated model views, and model query interface with results caching. The methodology aims at a de-centralized approach to multi-model and multi-scale collaboration that maintains the cornerstones of traceability and reproducibility. It is demonstrated with a multi-model coil design optimization of a high-field superconducting magnet.

Magnetization and Flux Penetration of YBCO CORC Cable Segments at the Injection Fields of Accelerator Magnets

High-temperature-superconducting (HTS) cables are being considered for use in particle accelerator beam steering magnets. Knowledge of the magnetic properties of these HTS cables is needed for accelerator magnet design. Here, we present the results from a Hall probe magnetometer made for measuring the M-μ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> H of short sections of superconducting cables in applied magnetic fields up to 12 T. The M-μ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> H of a CORC cable was measured with field sweeps of ± 4.5 T and also a -2- to 8-T loop. Relevant to a particle accelerator with an injection field of 1 T, the magnetization M <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">inj</sub> of the CORC cable was ≅ 900 kA/m and the penetration field B <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</sub> ≅ 1 T. The magnetization and penetration field of the cables are compared to tape from which the cables were wound, and the results are compared to NbTi and Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn conductors.

Effect of Epoxy Volume Fraction on the Stiffness of Nb3Sn Rutherford Cable Stacks

For the optimization of Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn superconducting accelerator magnet design and assembly parameters the stress-strain behavior of the coils needs to be known. We have measured the stiffness of Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn Rutherford cable stacks with different epoxy volume fraction. The cable stack stiffness is strongly dependent on the load direction. The highest stiffness of about 95 GPa is measured in axial direction, as predicted by the rule of mixtures. In transverse load direction the stiffness is stress dependent, and about half of the axial stiffness. As expected the stiffness of the cable stacks increases with decreasing epoxy volume fraction. The stiffness of a conductor block extracted from an already cold tested 11 T dipole coil is comparable to that of a ten-stack sample with similar epoxy volume fraction.

Magnetic and Mechanical Design of a 16 T Common Coil Dipole for an FCC

A EuroCirCol is a conceptual design study for a post-LHC research infrastructure based on an energy-frontier 100 TeV circular hadron collider. In the frame of the high-field accelerator magnet design work package of this study, the feasibility of a 16 T dipole in a common coil configuration is being studied. This paper shows the electromagnetic design optimization performed to achieve the required field quality while minimizing the superconductor volume and taking into account the input parameters and assumptions of the EuroCirCol study. The finite element models have been used to analyze the stress distribution and deformations under the large Lorentz forces due to the very high magnetic field. Several iterations have been necessary to obtain a feasible magnet design. The 3-D electromagnetic calculations are also included in this paper.

EuroCirCol 16 T Block-Coils Dipole Option for the Future Circular Collider

EuroCirCol is a conceptual design study for a post-LHC research infrastructure based on an energy-frontier 100 TeV circular hadron collider. In the frame of the high field accelerator magnet design work package of this study, three different layouts for double-aperture dipole magnets made of Nb 3 Sn conductors and providing a field of 16 T in a 50-mm aperture are being considered: block-coils, common-coils, and cosine-theta. All options are being explored and will be compared based on the same assumptions, in particular with regards to conductor performance, operating temperature and margin. This paper details the block-option presently under development at CEA. After an exploratory phase of various block-coils possibilities (cable dimensions, number of layers, cable grading) the design converged to a four layer magnet. An internal grading-two different geometries of cables are used in the coil-driven by a conductor saving is required. An electromagnetic analysis of the magnet cross-section in a 2-in-1 configuration is performed, coupled to a protection investigation. Preliminary results of a mechanical study on a bladder-and-key single aperture magnet are also reported.

The EuroCirCol 16T Cosine–Theta Dipole Option for the FCC

EuroCirCol is a conceptual design study for a post-LHC research infrastructure based on an energy-frontier of the 100-TeV circular hadron collider “Future Circular Collider.” In the frame of the high-field accelerator magnet design work package of this study, three different options for dipole magnets providing a field of 16 T in a 50-mm aperture are being considered: block-coils, common-coils, and cosine-theta. All options are being explored and will be compared based on the same assumptions, in particular for what regards the conductor performance, operating temperature, and margin. This paper details the cosine-theta option under development at INFN, showing the electromagnetic and mechanical choices.

EuroCirCol 16 T Common-Coil Dipole Option for the FCC

EuroCirCol is a conceptual design study for a post-LHC research infrastructure based on an energy-frontier 100 TeV circular hadron collider. In the frame of the high-field accelerator magnet design work package of this study, three different options for dipole magnets providing a field of 16 T in a 50 mm aperture are being considered: block-coil, common-coil, and cosine-theta. All options are being explored and will be compared based on the same assumptions, in particular for what regards the conductor performance, operating temperature and margin. This paper details the common-coil option under development at CIEMAT, with special attention to the electromagnetic calculations and quench simulation.

Field Quality Dependence on Vacuum Chamber Materials in Quadrupole Magnets

In accelerator magnet design, important criteria are the magnetic field distribution and the magnetic field quality. Accelerator magnets are usually designed for the ideal case in which no magnetic material is present in the field region. In practice, however, the presence of a vacuum chamber inside the magnet aperture can affect the magnetic field in case its material has nonnegligible relative permeability. We quantify this effect based on numerical simulations with a conventional quadrupole magnet model. The results show that there is a measurable effect of the configuration, the material choice, and the presence of welding seam in particular.

Quantification of Uncertainty in the Field Quality of Magnets Originating from Material Measurements

A challenge in accelerator magnet design is the strong nonlinear behavior due to magnetic saturation. In practice, the underlying nonlinear saturation curve is modeled according to measurement data that typically contain uncertainties. The electromagnetic fields and in particular the multipole coefficients that heavily affect the particle beam dynamics inherit this uncertainty. In this paper, we propose a stochastic model to describe the uncertainties and we demonstrate the use of generalized polynomial chaos for the uncertainty quantification of the multipole coefficients. In contrast to previous works we propose to start the stochastic analysis from uncertain measurement data instead of uncertain material properties and we propose to determine the sensitivities by a Sobol decomposition.

The double-helix dipole-a novel approach to accelerator magnet design

We describe a new technology for superconducting dipoles that has significant advantages for use in particle accelerators. The dipole field is obtained by using concentric pairs of helically-wound coils that are tilted at opposite angles; this effectively cancels the solenoid component of the field and adds the dipole content of each layer. This coil configuration produces a dipole field with systematic errors <10/sup -8/ of the main field in 85% of the coil aperture. We show, using a design example, how many of the inherent problems with the traditional cosine theta type of coil are eliminated and the cost of development and manufacturing the magnets is substantially reduced.

Magnetic designs and field quality of Nb/sub 3/Sn accelerator magnets

This paper presents a new approach to accelerator magnet design, based on simple and robust single-layer coils with minimum number of turns arranged horizontally or vertically in a common iron yoke. Cos-theta and block type coil geometries as well as cold and warm iron yoke designs were studied. Coils and yokes were optimized for the maximum field, minimum field harmonics, and minimum sizes.

Review of accelerator magnet design in the world

It is pointed out that the construction of large particle accelerators and storage rings requires the design and fabrication of large numbers of bending, focusing, and correction magnets. Normal conducting iron yoke magnets are standard for low fields. Two designs representing efforts for manufacturing cost reduction are discussed. Emphasis is placed on superconducting magnets necessary for high fields. Many details of the well-established cos theta one or two layer coil design using NbTi superconductor are presented. Peculiarities in the use of Nb/sub 3/Sn superconducting material are mentioned. Examples of alternative superconducting magnet designs are given. Finally, the performance of HERA (Hadron-Electron Ring Accelerator) magnets produced in quantity by industry is presented.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

3D accelerator magnet calculations using MAGNUS-3D

The steady trend towards increased magnetic and geometric complexity in the design of accelerator magnets has caused a need for reliable 3D computer models and a better understanding of the behavior of magnetic system in three dimensions. The capabilities of the MAGNUS-3D family of programs are ideally suited to solve this class of problems and provide insight into 3D effects. MAGNUS-3D can solve any problem of magnetostatics involving permanent magnets, nonlinear ferromagnetic materials and electric conductors. MAGNUS-3D uses the finite element method and the two-scalar-potentials formulation of Maxwell's equations to obtain the solution, which can then be used interactively to obtain tables of field components at specified points or lines, plots of field lines, function graphs representing a field component plotted against a coordinate along any line in space (such as the beam line), and views of the conductors, the mesh and the magnetic bodies. The magnetic quantities that can be calculated include the force or torque on conductors or magnetic parts, the energy, the flux through a specified surface, line integrals of any field component along any line in space, and the average field or potential harmonic coefficients. We describe the programs with emphasis placed on their use for accelerator magnet design, and present an advanced example of actual calculations.

High Field Accelerator Magnet Design (10T, 2T/cm), Material and Model Development

Two accelerator magnets have been designed and developed to a manufacturable prototype. Most of the dipole calculations presented will be based on a four shell, five kiloampere/turn, five centimeter aperature magnet, approximately six meters long. Two designs are considered: a dipole bending magnet and the quadrupole focusing magnet. The mechanical and electrical coil parameters are listed.