Analysis of sudden quench of an ITER superconducting NbTi full-size short sample using the THELMA code

Zanino, Roberto; Bellina, F.; Ribani, P.L.; Savoldi, Laura

doi:10.1088/0953-2048/24/10/105001

Cited by 6 publications

(4 citation statements)

References 44 publications

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“…Once the cable detailed geometrical model is created, with all the strands individually modelled, it is possible to create automatically cable simplified models which make use of equivalent macrostrands, to be adopted for the electromagnetic (EM) and/or the thermal analysis [10]. The axis geometry of each macrostrand is computed as the barycentric line of all the strands represented by the macrostrand and the inter-macrostrands contact conductance G i,j is computed as G i,j = ∀k∈i,∀s∈j G k,s , where k and s are the indexes of the strands involved.…”

Section: A Geometric Modelmentioning

confidence: 99%

Numerical Investigation on Induced Current Distribution and AC Losses in a Prototype Cable for the European DEMO TF Coils

Stacchi

Bellina

Breschi

et al. 2019

IEEE Trans. Appl. Supercond.

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A new geometrical model has been implemented in the THELMA code, aiming at permitting the study of multi-stage, forced-flow cable-in-conduit conductors with rectangular crosssection, like that proposed for the TF magnets of the future fusion reactor DEMO. This model gives verisimilar strands trajectories which should enable the adoption of a more detailed interstrand electrical contact model. The paper shows the results of the first application of these code new features to a set of contact resistance and AC losses experiments carried out by Twente University on a DEMO TF prototype conductor. The results of this analysis present some unforeseen aspects that need further work to be fully understood, to improve and validate the model.

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Section: A Geometric Modelmentioning

confidence: 99%

Numerical Investigation on Induced Current Distribution and AC Losses in a Prototype Cable for the European DEMO TF Coils

Stacchi

Bellina

Breschi

et al. 2019

IEEE Trans. Appl. Supercond.

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“…17 Therefore, a coupled thermal-hydraulic/electromagnetic model is needed to account for current redistribution as well as temperature non-uniformities at sub-cable levels. 18 where n = 1.35 s is the coupling time constant,  is the permeability of the magnetic field in vacuum,…”

Section: Simulation Setupmentioning

confidence: 99%

Quench Propagation in a TF Coil of the EU DEMO

Savoldi

Bonifetto

Brighenti

et al. 2017

Fusion Science and Technology

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The design of a suitable quench protection system is fundamental for the safe operation of superconducting magnets and in turn requires the accurate simulation of the quench transient. The quench propagation in a toroidal field (TF) coil for the future European fusion reactor (EU DEMO) is analyzed here considering the latest, layer-wound winding pack (WP) design proposed by ENEA. The thermal-hydraulic model of a TF coil implemented in the 4C code is updated by including the external cryogenic circuits of the WP and of the casing cooling channels and proposing a preliminary layout of the quench lines. Three different locations are considered for the quench initiation: maximum temperature margin in the WP, and minimum and maximum temperature margin on the same turn of the innermost layer. The evolution of the main electrical and thermal-hydraulic parameters is simulated, such as voltage along each layer, quench front propagation both along and across the layers, hot spot temperature, pressurization of the coil and coolant mass flow rate at the coil boundaries, so that the 4C code provides a reliable (in view of its validation) and detailed virtual monitor of what happens inside the coil during the quench transient. In all cases considered, the ENEA design is predicted to satisfy the present (i.e., ITER) design criteria concerning the maximum allowed hot spot temperature.

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“…The production of the magnet conductor has been accomplished and an independent evaluation of the solenoid performance in terms of current margin and losses has been done in addition to the design calculations. A detailed analysis of the electromagnetic performances has been therefore carried out with the THELMA code [2], focusing on the electromagnetic (EM) losses in the cable at different ramp rates and coolant temperatures, to assess the magnet stability.…”

Section: Introductionmentioning

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 sudden quench of an ITER superconducting NbTi full-size short sample using the THELMA code

Cited by 6 publications

References 44 publications

Numerical Investigation on Induced Current Distribution and AC Losses in a Prototype Cable for the European DEMO TF Coils

Numerical Investigation on Induced Current Distribution and AC Losses in a Prototype Cable for the European DEMO TF Coils

Quench Propagation in a TF Coil of the EU DEMO

Coupled Thermal and Electromagnetic Analysis of the NAFASSY Magnet

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