Conceptual design of high transverse field magnets at the NHMFL

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The National High Magnetic Field Laboratory (NHMFL) in Tallahassee, Florida, USA, continues research and development of transverse field magnets (with the field perpendicular to the access tube). Presently, the emphasis is on a novel approach with concentric nested coils tilted at an angle to the central axis; current flows in opposite directions within the coils at opposite tilt angle, generating a transverse dipole field. Superconducting tilted coils using wire-wound technology and resistive tilted coils using advanced technology are being examined. Some very preliminary, conceptual designs and magnetic field calculations are presented. Related problems, including behavior under the Lorentz forces are discussed briefly.Index Terms-Dipole magnet, nondestructive repetitively pulsed magnet, superconducting winding, transverse field.

Section: Transverse Field Pulse Magnetmentioning

confidence: 95%

Section: Superconducting Tilted Coils Manufacturing Problemsmentioning

confidence: 99%

New concepts in transverse field magnet design

Gavrilin

Bird

Кейлин³

et al. 2003

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“…An elliptic bore magnet is the first choice to examine, because there is an analytical solution for a Bitter disk whose outer and inner boundaries are homothetic ellipses [2][3][4]; there also exists an analytical solution for a Bitter disk with confocal elliptical outer and inner boundaries as well (see [4]). In [2][3][4], these solutions were used to calculate the magnetic field generated by a so-called tilted (canted) coil assembled from elliptic Bitter disks at an angle to the coil axis to form the circular bore [5,6]; the very first conceptual design of a Bitter magnet consisted of such coils was suggested by M.D. Bird [6].…”

Section: Introductionmentioning

confidence: 99%

“…In [2][3][4], these solutions were used to calculate the magnetic field generated by a so-called tilted (canted) coil assembled from elliptic Bitter disks at an angle to the coil axis to form the circular bore [5,6]; the very first conceptual design of a Bitter magnet consisted of such coils was suggested by M.D. Bird [6]. However, the same mathematical apparatus can be also employed to calculate the magnetic field of an elliptic bore Bitter coil assembled from elliptic disks at a 90-degree angle w.r.t.…”

Section: Introductionmentioning

confidence: 99%

Energy and Material Efficient Noncircular Bore Bitter Magnets

Akhmeteli¹,

Gavrilin

Dixon

2018

 There exist a number of experiments/applications where the second dimension of the bore of Bitter magnets is not fully utilized. Using an analytical solution for elliptical bore coils, we show that reducing one of the dimensions of the bore can lead to considerable decrease in consumed power and/or coil material. The results of additional numerical computation show that a 20% higher magnetic field can be achieved for an elliptical bore and racetrack bore coils with 1:10 ratio of the transverse dimensions of the bore than for a circular bore coil with the same larger transverse dimension of the bore, consumed power, and disk area.

“…The idea reappeared in a series of publications [2]- [5] that, by not crediting the 1970's publication, may have been unaware of it. With renewed interest in high field Nb 3 Sn magnets at LBNL and CERN [6], [7] the idea gained interest leading to the construction a small dipole magnet.…”

mentioning

confidence: 99%

Design, Fabrication, and Test of a Superconducting Dipole Magnet Based on Tilted Solenoids

Caspi

Dietderich

Ferracin

et al. 2007

Abstract-It can be shown that, by superposing two solenoid-like thin windings that are oppositely skewed (tilted) with respect to the bore axis, the combined current density on the surface is "costheta" like and the resulting magnetic field in the bore is a pure dipole. As a proof of principle, such a magnet was designed, built and tested as part of a summer undergraduate intern project. The measured field in the 25mm bore, 4 single strand layers using NbTi superconductor, exceeded 1 T. The simplicity of this high field quality design, void of typical wedges end-spacers and coil assembly, is especially suitable for insert-coils using High Temperature Superconducting wire as well as for low cost superconducting accelerator magnets for High Energy Physics. Details of the design, construction and test are reported.Index Terms-Superconducting magnet, pure dipole, insert magnet, tilted solenoid. I. INTRODUCTIONn a published paper by D.I. Meyer and R. Flasck in 1970 [1] the authors discussed the magnetic field resulting from the superposition of two oppositely skewed (tilted) solenoids with respect to the bore axis (Fig. 1) presently building a similar quadrupole magnet. Advantages of this concept are as follows: 1) high field quality in an extended dynamic range, 2) no field optimization required, 3) small number of components -wedges and spacers not needed, 4) coil assembly not needed (all poles are wound together around a single bore), 5) small bore sizes not limiting "cos-theta" windings, 6) continuous windings and ease of magnet "grading". There are also other open issues such as magnet protection and pre-stress that will need to be addressed in the future. The concept can work well for "stand alone" accelerator magnet as well as insert coils to existing magnets. The technology is particularly suitable for Nb 3 Sn conductor as well as high temperature superconducting wires. In section II we give a short mathematical proof addressing the perfect dipole quality followed, in section III, with details on the magnet design and construction. In section IV we report test results and draw final conclusions. A. Mathematical ModelA simplified mathematical proof is used to show that skewed windings on the surface of a cylindrical correspond to an axial current-density distribution that is ϑ cos like, and therefore produce a "pure" dipole field. The current density flow lines that are distributed on the surface of the cylinder are elliptical (inclination angle α with respect to the cylinder axis) with flow lines coordinates expressed as (see Fig. 1-2 Since the current density is divergence free,