Temporal resistance variation of the second generation HTS tape during superconducting-to-normal state transition
© Malginov et al.; licensee Springer. 2013
Received: 16 May 2013
Accepted: 1 November 2013
Published: 9 November 2013
The quench process in high-temperature superconducting (HTS) wires plays an important role in superconducting power devices, such as fault current limiters, magnets, cables, etc. The superconducting device should survive after the overheating due to quench.
We studied the evolution of the resistance of the YBCO tape wire during the quench process with 1 ms time resolution for various excitation voltages.
The resistive normal zone was found to be located in a domain of about 1-4 cm long. The normal state nucleation begins in 40-60 ms after voltage is applied across the HTS tape. In subsequent 200-300 ms other normal state regions appear. The normal domain heating continues in the following 5-10s that results in a factor of 2–3 increase of its resistance.
Formation of the normal domain during the quench process follows the same stages for different excitation voltages. Characteristic domain sizes, lifetimes and temperatures are determined for all stages.
The quench process in high-temperature superconducting (HTS) wires plays an important role in superconducting fault current limiter operation. It occurs when current in a wire exceeds the critical value and as a result, the wire resistance becomes nonzero. The problem of quench stability is related to the heat transfer and is especially crucial for the Second Generation HTS wires on highly resistive substrates. We present here the results of studies of the normal zone generation.
Methods and results
We studied the process of quench in HTS tapes using the experimental procedure described in (Fleishman et al., 2010). The sample was 12 mm wide and 100 mm long SuperPower YBCO tape SF12100 (Super-power). Both nominal and measured critical currents at 77 K are about 300A. It consists of 100 mu of Hastelloy substrate, 1 mu YBCO (critical temperature Tc = 91 K) and 1.5mu Ag layers. Measurements were performed with the tape immersed in liquid nitrogen. The AC (50 Hz) voltage step with the amplitude V0 was applied to the sample at the time t0. After that, during the subsequent 40s, we registered the current I and sample AC resistance Z with 1 ms time resolution.
here L (mm) is the length of the zone where T > Tc for t > t1, V0 (mV) is the applied voltage magnitude.
From the above results we conclude that during the superconducting-to-normal state transition in HTS tape the normal phase is limited to a single domain. The domain nucleates in 40-60 ms after the voltage is applied. In the subsequent 5-10s the domain heats up; it results in 2–3 times increase of the resistance. Central part of the domain is about 20-30 mm long. Inside the both of the 3-5 mm long edges of the domain the temperature falls from the maximal temperature TM to 90 K.
This work was supported by Russian Foundation for Basic Research (Grant 14-08-00418-a and Grant 12-08-31415-mol-a), Programs of Russian Academy of Sciences, Russian Ministry of Education and Sciences (Grant 8203), Russian science support foundation and using facilities of the Shared Research Equipment Center at LPI.
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- Mal’ginov AV, Yu Kuntsevich A, Mal’ginov VA, Fleishman LS: Normal domain temperature profile in second generation HTS tape wire. SpringerPlus 2013, 2: 535. 10.1186/2193-1801-2-535View ArticleGoogle Scholar
- Super-power http://www.superpower-inc.com/
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