Results and analysis of the hot-spot temperature experiment for a cable-in-conduit conductor with thick conduit

Sedlák, Kamil; Bruzzone, P.

doi:10.1016/j.cryogenics.2015.07.003

Cited by 8 publications

(2 citation statements)

References 6 publications

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“… the jacket cross section in DL5.2 is ~2.5 times larger than in DL1.1, see the different thickness in Fig. 1a; being the jacket heat capacity at relatively high temperature (~100 K) ~2 orders of magnitude larger than that of the He, the jacket thickness grading (due to structural reasons) provides, as a fringe benefit, a higher thermal capacity in DL5.2, contributing to reduce the hot spot temperature, as already noted elsewhere; 20  the higher magnetic field in DL1.1 also results in an increase of the copper wires magnetoresistance, partially contributing to the temperature increase in the hot spot region of the inner DLs.…”

Section: Resultssupporting

confidence: 62%

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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Section: Resultssupporting

confidence: 62%

Quench Propagation in a TF Coil of the EU DEMO

Savoldi

Bonifetto

Brighenti

et al. 2017

Fusion Science and Technology

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“…It also highlighted the advantages of the embedded cowound voltage taps and optical fiber detection methods over the hydraulic techniques based on the absolute pressure and mass flow rate of helium [31]. The hot-spot evolution has also been studied experimentally [32], indicating at the importance of a thermal coupling between the cable and jacket.…”

Section: Introductionmentioning

confidence: 99%

Experimental study of stability, quench propagation and detection methods on 15 kA sub-scale HTS fusion conductors in SULTAN

Bykovskiy

Bajas

Dicuonzo

et al. 2023

Supercond. Sci. Technol.

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High-temperature superconductors (HTS) enable exclusive operating conditions for fusion magnets, boosting their performance up to 20 T generated magnetic fields, in the temperature range from 4 K to 20 K. One of the main technological issues of the HTS conductors is focused on their protection in the case of a thermal runaway (quench). In spite of extremely high thermal stability of HTS materials, quench is still possible due to local defects along the conductor length or insufficient cooling. In such cases, the high stability results in slow propagation of a resistive zone. Thereby, risky hot-spot temperature (>200 K) can be reached, if applying conventional quench detection methods at the voltage threshold of 0.1 – 0.5 V, typical for fusion magnets. Aiming at experimental study of the phenomenon, a series of sub-scale 15 kA 3.6 m long conductors based on stack of tapes soldered in copper profiles are manufactured at Swiss Plasma Center, including twisted ReBCO and BiSCCO triplets, non-twisted and solder-filled ReBCO triplets, as well as indirectly cooled non-twisted ReBCO single strand. Applying either increasing helium inlet temperature, overcurrent operation or energy deposited by embedded cartridge heaters, critical values of the electric field and temperature are evaluated for a given operating current (up to 15 kA) and background magnetic field (up to 10.9 T). Once quench is actually triggered, the quench propagation is studied by distributed voltage taps and temperature sensors able to monitor the external temperature of the jacket and internal one of the conductor (helium or copper). Thanks to the recent upgrade of the SULTAN test facility, quench propagation in the conductors is measured up to the total voltage of 2 V and peak temperature of 320 K. Furthermore, novel quench detection methods based on superconducting insulated wires and fiber optics are also instrumented and studied. Summary of the test samples, their instrumentation and corresponding test results is presented in this work.

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