Analysis of Heat Load, Current Margin and Current Nonuniformity in ITER PF Coil Joints

Rolando, G.; Lanen, E. van; Nugteren, J. van; Offringa, Wietse; Kate, Herman H.J. ten; Ilin, Y.; Lim, Byung Su; Simon, Fabrice; Nijhuis, A.

doi:10.1109/tasc.2012.2236131

Cited by 6 publications

(6 citation statements)

References 10 publications

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“…Heat exchange between adjacent petals and between petals and the central channel is conveyed through the helium [24]. The general assumption that the helium mass flow in the bundle region of the conductor is 1/3 of the total mass flow is adopted in the model [25].…”

Section: Thermal Modelmentioning

confidence: 99%

Temperature and current margin of ITER central solenoid conductor designs during a 15 MA plasma scenario

Rolando

Devred

Nijhuis

2013

Supercond. Sci. Technol.

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The plasma current of the international thermonuclear experimental reactor (ITER) will be induced by current pulses in the central solenoid (CS). The foreseen lifetime and operating conditions, with currents up to 45 kA at 13 T, pose significant mechanical challenges for the brittle Nb 3 Sn strands. On top of this, inter-strand coupling loss should remain restricted during pulsed operation to ensure an achievable repetition rate of plasma cycles. In order to address the degradation of Nb 3 Sn cable-in-conduit conductors (CICCs) with electromagnetic and thermal load cycling, four alternative cable designs have recently been tested in both DC and AC modes.However, the actual operating conditions experienced by the CS conductor within the ITER magnet system in terms of time-varying magnetic field and current cannot be fully reproduced in existing experimental facilities. In this paper, we present the results of the numerical assessment of the electromagnetic performance of the four ITER CS conductor designs during a 15 MA plasma scenario. The analysis was carried out with the code JackPot-ACDC including the voltage-current characteristic of all superconducting strands.

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Section: Thermal Modelmentioning

confidence: 99%

Temperature and current margin of ITER central solenoid conductor designs during a 15 MA plasma scenario

Rolando

Devred

Nijhuis

2013

Supercond. Sci. Technol.

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“…Since a quench is not directly detected in the JackPot model, the impact of the patches on the current redistribution and stability is evaluated by means of examining the current margin of the strands. The current margin is defined as I margin = Min(I c −|I s |) [18], a negative current margin means the strand current exceeds the critical current. In addition, the number of strands with negative current margin is also detected.…”

Section: Non-homogeneous Contact Resistance Between Strand and Copper...mentioning

confidence: 99%

Modeling and validation of nonlinear voltage-current characteristics of ITER PF joint sample tested in the SULTAN facility

Huang

Bagni

Ilyin

et al. 2022

Supercond. Sci. Technol.

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The ITER Poloidal Field (PF) coils are wound into double pancakes with NbTi cable-in-conduit conductors, which are connected by joints in shaking hands lap-type configuration. The coils are operating in pulsed mode with a maximum operating current of 55 kA and peak magnetic field of 6.4 T, utilizing electromagnetic load on the conductors and joints. A series of PF qualification joint samples modified in praying hands configuration is measured in the SULTAN facility. For some samples, a nonlinear voltage-current (VI) characteristic is observed during the assessment of joint resistance. The growth of joint resistance versus the B×I product is larger than what is expected from the magneto-resistant copper contribution. Two non-homogeneous contact resistance models are developed and combined to quantitatively evaluate the reason for the nonlinear VI behavior in combination with the relevant power dissipation and current redistribution in the joint. The simulations reveal that, for the particular pre-qualification PFJEU2 sample with resistance variation up to 3.5 nΩ, the most probable reason for the nonlinear VI characteristic is a widely spread defective connection between copper sole and shim. The electromagnetic force involves a separation effect on the mechanically and electrically weakly connected parts, resulting into a varying resistance depending on transport current and background field. The hypothesis and models are validated by an experiment on a similar sample PFJEU3 and a post-mortem examination of the PFJEU2 sample.

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“…When a part of a coil is modelled, in our case a single turn, a Neumann condition, that is a uniform current distribution, has been frequently assumed among the strands at the model boundaries [15]. In our case a parametric model has been adopted, in which the cable elements are connected at their ends to two suitable stars of resistors, that must also be representative of the magnet terminations.…”

Section: B Choice Of the Boundary Conditionsmentioning

confidence: 99%

Coupled Thermal and Electromagnetic Analysis of the NAFASSY Magnet

Manfreda

Bellina

Corato

et al. 2015

IEEE Trans. Appl. Supercond.

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The paper presents an analysis of the current distribution and electromagnetic losses in the NAFASSY magnet carried out with the THELMA code, thanks to a brand-new thermal module coupled with the pre-existing electromagnetic module. The non-linear thermal and electrical properties of both superconducting and copper strands, depending on the local temperature, current density and magnetic field, are taken into account. The model analyses a single turn of the magnet, located in the highest field zone, focusing on the current distribution in the cable, the coupling AC and DC losses during ramped waveforms. The results are then extrapolated to estimate the behaviour of the overall magnet. A description of the models is given, together with a parametric analysis of different boundary conditions and cable discretizations. The analysis shows that, in nominal working conditions, no thermal instability should take place. However, local current redistribution among the strands may occur, mainly driven by the interstrand contact pattern, the local magnetic field and the strand current density.

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Analysis of Heat Load, Current Margin and Current Nonuniformity in ITER PF Coil Joints

Cited by 6 publications

References 10 publications

Temperature and current margin of ITER central solenoid conductor designs during a 15 MA plasma scenario

Temperature and current margin of ITER central solenoid conductor designs during a 15 MA plasma scenario

Modeling and validation of nonlinear voltage-current characteristics of ITER PF joint sample tested in the SULTAN facility

Coupled Thermal and Electromagnetic Analysis of the NAFASSY Magnet

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