Periodicity of crossover currents in a Rutherford-type cable subjected to a time-dependent magnetic field

Akhmetov, A.A.; Devred, A.; Ogitsu, T.

doi:10.1063/1.356172

Cited by 42 publications

(20 citation statements)

References 6 publications

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“…non-uniform cable cross-contact resistance Rc along the length of the cable [6] The first two mechanisms result in a current redistribution process along the cable analog to a current diffusion process with very long time constants up to steady-state [10]. Both are critical with respect to parameters that are very difficult to control in the magnet.…”

Section: Discussionmentioning

confidence: 99%

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Experimental evidence of boundary induced coupling currents in LHC prototypes

Bottura

Walckiers

Ang

1997

IEEE Trans. Appl. Supercond.

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The field quality of 10 m long LHC dipole models has been measured with short rotating coils to explore its dependence on time and position. Multipoles exhibit a longitudinal periodic variation, with period equal to the twist pitch length. This periodicity is shown here to have at least two components with very different time constants. The amplitude of the component with the shorter time constant, in the range of 100 to 300 s, depends on position and time. Larger amplitudes are measured at early times after a ramp and close to regions with incomplete cable transposition with respect to the non-uniform external field change. As the multipoles periodicity is due to current imbalance in the cables, we attribute the short time scale variations to the presence of space and time decaying boundary induced coupling currents (BICC's) in the cable. An estimate of their value is given.

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Section: Discussionmentioning

confidence: 99%

“…The origin of this periodic variation, with a period identical to the inner layer cable twist pitch, is attributed to current distribution imbalance within the cable [5][6][7][8][9][10]. Such periodicity has already been measured on long models of the Large Hadron Collider (LHC) dipoles [4].…”

Section: Introductionmentioning

confidence: 99%

Experimental evidence of boundary induced coupling currents in LHC prototypes

Bottura

Walckiers

Ang

1997

IEEE Trans. Appl. Supercond.

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“…Akhmetov, Devred and Ogitsu [54] have extended the above analysis to the case that the inter-strand resistances and the branch currents are allowed to vary along the magnet axis. They subdivide the cable into columns along the axis which are labelled by an index k. This is sketched in Fig.…”

Section: Two Dimensional Modelmentioning

confidence: 99%

Superconductivity in high energy particle accelerators

Schmüser

2002

Progress in Particle and Nuclear Physics

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“…Only if the cable is infinitely long, there is one degenerated solution for which the crossover currents are not periodic but uniform along the cable. The same method was also used to calculate the coupling currents in finite and infinite Rutherford-type cables subject to, especially, sinusoidally varying magnetic fields along the cable axis 13,14 . Only the steady-state current pattern could be modelled.…”

Section: Calculating Biccsmentioning

confidence: 99%

Review on Boundary-Induced Coupling Currents

Verweij

1998

Advances in Cryogenic Engineering Materials

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* LHC DivisionPresented at CEC/ICMC '97, Portland Boundary-Induced Coupling Currents (BICCs) are generated in multistrand superconducting cables during a field sweep if a) the field sweep and/or b) the electrical contacts between the strands of the cable vary along the cable. Typical parts in a coil which cause large BICCs are the connections between two cables in or outside a coil and the coil ends of racetrack magnets.In the first part of the paper several approaches for describing and calculating BICCs are reviewed. Attention is paid on the steady-state as well as the time dependent solutions.In the second part of the paper the consequences of BICCs on the behaviour of magnets are discussed. These are additional field variations along the magnet length, additional coupling losses and a non-uniform distribution of coupling losses and current among the strands, resulting in a reduced stability. Several effects are illustrated by means of measurements on model dipole magnets. It is shown how the additive effect of all the BICCs in a coil is rather unpredictable so that similar coils can have rather different BICC related behaviour.2

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Periodicity of crossover currents in a Rutherford-type cable subjected to a time-dependent magnetic field

Abstract: Articles you may be interested inCalculation of optical rotation with time-periodic magnetic-field-dependent basis functions in approximate time-dependent density-functional theory

Cited by 42 publications

References 6 publications

Experimental evidence of boundary induced coupling currents in LHC prototypes

Experimental evidence of boundary induced coupling currents in LHC prototypes

Superconductivity in high energy particle accelerators

Review on Boundary-Induced Coupling Currents

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