Dendritic flux avalanches in a superconducting MgB<sub>2</sub>tape

Qureishy, Thomas; Laliena, Carlos; Martínez, Elena; Qviller, Atle Jorstad; Vestgården, Jørn Inge; Johansen, T. H.; Navarro, Rafael; Mikheenko, P.

doi:10.1088/1361-6668/aa9244

Cited by 9 publications

(6 citation statements)

References 32 publications

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“…The lower (orange) dots indicate the transition to finger-like avalanches and the upper (blue) dots the transition to dendritic avalanches. The observed small variation of the threshold field at low temperatures is a general characteristic also reported in MgB 2 films 39 and tapes 40 . Closed-form expressions for the threshold magnetic field were recently derived for different regimes where the onset of avalanches is delayed either by heat diffusion through the superconducting sample, by the specific heat of superconductor or by heat evacuation through the substrate 10 .…”

Section: Threshold Magnetic Field Of Thermomagnetic Breakdownsupporting

confidence: 80%

Statistics of thermomagnetic breakdown in Nb superconducting films

Alvarez¹,

Brisbois²,

Melinte³

et al. 2019

Sci Rep

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Superconductors are well known for their ability to screen out magnetic fields. In type-II superconductors, as the magnetic field pressure is progressively increased, magnetic flux accumulates at the periphery of the sample, very much like charges accumulate in a capacitor when voltage is increased. As for capacitors, exceeding certain threshold field causes the blocked magnetic flux to abruptly penetrate into the sample. This phenomenon, triggered by a thermomagnetic instability, is somewhat analogous to the dielectric breakdown of the capacitor and leaves behind a similar Lichtenberg imprinting. Even though electrical breakdown threshold has been extensively studied in dielectrics, little information is known about the statistical distribution of the thermomagnetic breakdown in superconductors. In this work, we address this problem by performing magneto-optical imaging experiments on a Nb film where nanometric heating elements are used to rapidly erase the magnetic history of the sample. We demonstrate that the size and shape distributions of avalanches permits to unambiguously identify the transition between two regimes where either thermal diffusivity or magnetic diffusivity dominates. Clear criteria for discriminating athermal dynamic avalanches from thermally driven avalanches are introduced. This allows us to provide the first precise determination of the threshold field of the thermomagnetic breakdown and unveil the details of the transition from finger-like magnetic burst to dendritic branching morphology. These findings open a new avenue in the interdisciplinary exploration of catastrophic avalanches through non destructive repeatable experiments.

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Section: Threshold Magnetic Field Of Thermomagnetic Breakdownsupporting

confidence: 80%

Statistics of thermomagnetic breakdown in Nb superconducting films

Alvarez¹,

Brisbois²,

Melinte³

et al. 2019

Sci Rep

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“…Remarkably, when increasing the temperature, this sensitivity becomes more pronounced at higher temperature, leading to a qualitative change in the thermomagnetic state at T 0 = 15 K. The temperature dependence of the threshold magnetic field of the flux avalanche in the superconducting film for the two excitation modes mentioned above is shown in figure 3. At low temperature (T 0 ⩽ 10 K), the threshold field varies very slightly, which is also previously reported as a general characteristic of superconducting MgB 2 films [60] and tapes [3]. As the temperature increases beyond 11 K, one can find that the artificially superposed magnetic perturbation can significantly reduce the threshold field for the onset of the dendritic avalanche.…”

Section: Resultssupporting

confidence: 77%

“…in which κ and c are the thermal conductivity and the specific heat of the superconductor, T 0 is the substrate temperature, which is fixed with a constant, and h is the heat transfer coefficient between the superconducting film and the substrate. The thermal parameters depend on the temperature, and are assumed as κ = κ 0 (T/T c ) 3 , c = c 0 (T/T c ) 3 , and h = h 0 (T/T c ) 3 [22]. In this thermomagnetic model, the flux avalanches are modeled by coupling the equations describing nonlocal and nonlinear electrodynamics (equations ( 1) and ( 2)) with an equation (equation ( 3)) for the increase and propagation of the heat.…”

Section: Thermomagnetic Modelmentioning

confidence: 99%

“…Thermomagnetic instability is one of the crucial factors that limits the safe and stable operation of superconducting devices, which has been observed by magnetic-optical imaging (MOI) in the form of flux avalanches in superconducting films of different materials (e.g. MgB 2 [1][2][3], YBa 2 Cu 3 O 7−δ [4][5][6][7], Pb [8,9], Nb [10][11][12], Nb 3 Sn [13], NbN [14][15][16], a-MoSi [17], and V 3 Si [18]). Numerous efforts have been devoted to understanding and controlling flux avalanches.…”

Section: Introductionmentioning

confidence: 99%

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Sensitivity of the thermomagnetic instability in superconducting film to magnetic perturbation for electromagnetic interference detection

Jiang¹,

Xue²,

Zhou³

2022

Supercond. Sci. Technol.

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The time-varying magnetic field with electromagnetic perturbation is regarded as an important parameter to the thermomagnetic stability of superconducting film devices. In this work, using the thermomagnetic model, we investigate the sensitivity of thermomagnetic instability in the superconducting film exposed to a linear ramp magnetic field, superposed by additional AC magnetic perturbation with tunable amplitude and oscillation frequency. Surprisingly, we find that the thermomagnetic instability is a non-monotonic function with the increasing oscillation frequency of magnetic perturbation, depending on the working temperature and oscillation amplitude. The unexpected non-monotonic sensitivity of thermomagnetic instability is revealed by the characteristic oscillation of electric field which can not be aggravated by the AC magnetic perturbation with very high frequency. The findings of this paper demonstrate that the magnetic perturbation of very low or high frequency is not the main factor that triggers the thermomagnetic instability of superconducting films. Furthermore, using the magnetic moment measurement, we propose a possible electromagnetic interference detection by the superconducting film based on such non-monotonic sensitivity of the thermomagnetic instability, which can be used to detect the tunable target electromagnetic interference with characteristic frequency in a complex electromagnetic environment.

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“…The instability occurs when vortices escape from pinning centers, locally heating the material, thus promoting additional flux motion and generating a positive feedback that results in largescale flux avalanches. This phenomenon appears as flux jumps in wires and bulk superconductors [7][8][9], and as dendritic flux formations in thin films. The latter has been observed in a large number of superconductors important for practical applications, such as MgB 2 [10,11], Nb [12,13], YBCO [14], and NbN [15].…”

Section: Introductionmentioning

confidence: 99%

Magnetic flux instability in NbN films exposed to fast field sweep rates

Baruch-El

Baziljevich

Johansen

et al. 2018

Supercond. Sci. Technol.

Self Cite

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Magneto-optical imaging of dendritic flux instability is reported for NbN films exposed to magnetic fields ramped at a fast rate (0.1-3.2 kT s −1). The results show that as the magnetic ramp rate increases, the temperature and field range of the instability extends significantly. In particular, the lower and upper threshold fields (H th 1 and H , th 2 respectively) that bound the field range for dendritic instability are affected. The upper field is found to increase linearly with the applied field sweep rate, a behavior which is discussed in terms of a recent theoretical work (Vestgarden et al 2016 Phys. Rev. B 73 174511). The extended instability range should be taken into account in applications in which the superconducting films are exposed to rapid changes in the magnetic field.

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Dendritic flux avalanches in a superconducting MgB₂tape

Cited by 9 publications

References 32 publications

Statistics of thermomagnetic breakdown in Nb superconducting films

Statistics of thermomagnetic breakdown in Nb superconducting films

Sensitivity of the thermomagnetic instability in superconducting film to magnetic perturbation for electromagnetic interference detection

Magnetic flux instability in NbN films exposed to fast field sweep rates

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Dendritic flux avalanches in a superconducting MgB2tape

Cited by 9 publications

References 32 publications

Statistics of thermomagnetic breakdown in Nb superconducting films

Statistics of thermomagnetic breakdown in Nb superconducting films

Sensitivity of the thermomagnetic instability in superconducting film to magnetic perturbation for electromagnetic interference detection

Magnetic flux instability in NbN films exposed to fast field sweep rates

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Product

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Dendritic flux avalanches in a superconducting MgB₂tape