Superconducting double-helix accelerator magnets

Meinke, R.; Ball, M.J.; Goddzeit, C.L.

doi:10.1109/pac.2003.1288752

Cited by 17 publications

(7 citation statements)

References 2 publications

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“…The field inside of this coil is highly uniform, and a large gap toward the secondary winding does not lower the flux, which is designed for a value of about . The derivative of flux gives the voltage in the secondary winding according to (1) (1)…”

Section: B Flux Pump Conceptual Design and Operationmentioning

confidence: 99%

“…The novelty of the FPT lies in a HTS flux pump made of which enables the secondary flux pump coils to be connected in a persistent current loop with the rotor of the machine. Both the secondary FPT coils and rotor are double-helix, multi-layer dipole coils whose geometry is described in [1] and shown in Fig. 4 …”

Section: B Flux Pump Conceptual Design and Operationmentioning

confidence: 99%

“…T HE objective of this paper is to discuss the benefits of a HTS machine design based on the double-helix (DH) winding configuration [1] and a novel low loss HTS flux pump transformer (FPT). The FPT permits high current, persistent mode operation of the rotor, significantly simplifying quench protection, which is of particular importance for superconducting windings based on HTS conductor.…”

Section: Introductionmentioning

confidence: 99%

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Flux Pump Excited Double-Helix Rotor for Use in Synchronous Machines

Ishmael

Goodzeit

Masson

et al. 2008

IEEE Trans. Appl. Supercond.

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High temperature superconducting (HTS) machines have been demonstrated to benefit applications requiring high power density and torque. However, power density of existing superconducting machinery is limited by achievable flux density in the air gap and could be significantly increased with larger rotor currents. We propose a rotor based on MgB 2 conductor running in persistent current mode. A novel MgB 2 HTS flux pump transformer enables currents of several thousand amps in the rotor in a persistent mode. Large cryogenic heat loads associated with current leads are diminished by using a flux pump transformer for rotor excitation. All coils in the rotor and flux pump transformer are based on the double-helix winding configuration, which offers unmatched rotor robustness and reliability. This winding configuration also facilitates large bending radii, leading to an outstanding stress management and thus improved current carrying capacity of stress sensitive HTS conductors. The research presented in this paper analyses the performance of such a system through the design of a synchronous rotor for motors, generators and synchronous condensers.Index Terms-Double helix flux pump transformer (DH-FPT), double-helix winding configuration, generator and condenser, HTS, superconducting machinery, synchronous motor.

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Section: B Flux Pump Conceptual Design and Operationmentioning

confidence: 99%

Section: B Flux Pump Conceptual Design and Operationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Flux Pump Excited Double-Helix Rotor for Use in Synchronous Machines

Ishmael

Goodzeit

Masson

et al. 2008

IEEE Trans. Appl. Supercond.

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“…Hence, this principle is applied to the rotor of the SC machine, and found in the Double-Helix coils due to the intrinsic robustness of the winding. The Double-Helix's design offers the strength needed to sustain the large Lorentz forces associated with high currents [6]. Heavy containment structures used for compensating these forces can be significantly lightened if not totally removed depending on the machine design.…”

mentioning

confidence: 99%

EXPERIMENTAL INVESTIGATION OF MGB[sub 2] SWITCHING WITH MAGNETIC PULSES

Ishmael

Lévêque

Netter

et al. 2010

AIP Conference Proceedings

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Superconducting machines require DC current excitation in the rotor usually achieved using brushless exciters relying on solid state components for current rectification. The use of solid state components limits the amount of current allowable and imposes a large inductance in the rotor. MgB 2 allows for "close to" superconducting splicing enabling development of large current rotors where solid state devices could be advantageously replaced by superconducting switches and used with a flux pump excitation system. For certain applications, such as a synchronous condenser, the dynamics of the excitation system is important as well as imposing fast switching and fast recovery. Switches driven by magnetic pulses are expected to exhibit a very limited temperature increase leading to fast recovery and also to contribute to very good system dynamics. This paper covers the experimental investigation of the response of MgB 2 conductors subjected to magnetic pulses. The dependence of the resistance vs. J/Jc and operating temperature are discussed.

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“…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. As part of LBNL summer student program in 2005, we have designed, built and tested a superconducting dipole that is based on the concept of tilted solenoid windings.…”

mentioning

confidence: 99%

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

Caspi

Dietderich

Ferracin

et al. 2007

IEEE Trans. Appl. Supercond.

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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,

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Superconducting double-helix accelerator magnets

Cited by 17 publications

References 2 publications

Flux Pump Excited Double-Helix Rotor for Use in Synchronous Machines

Flux Pump Excited Double-Helix Rotor for Use in Synchronous Machines

EXPERIMENTAL INVESTIGATION OF MGB[sub 2] SWITCHING WITH MAGNETIC PULSES

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

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