Heat Diffusion in High-Cp Nb3Sn Composite Superconducting Wires
Abstract
:1. Introduction
2. Wire Sample Description
3. Experimental Setups and Methods
3.1. Sample Heat Treatment and Critical Current Measurement
3.2. Minimum Quench Energy (MQE) Measurement and Reproducibility
4. Finite Element Model
4.1. Quench Origin Mechanisms
4.2. Materials’ Properties
4.3. Wire Geometries
4.3.1. Hypertech Wires
- Wire diameter = 0.7 mm
- Cu-Sn rods radius = Gd2O3 corner subelement radius = 15 µm
- Maximum superconducting subelement width = 2 × 29/√3 µm
- Thickness between two sub-elements = 10 µm
- Stycast total width Wsty and height Hsty are 1.3 mm and 1.0 mm, respectively. Stycast center was displaced along y by (Hsty−Rwire)/8
- Gd2O3 central subelement radius = 23 µm
4.3.2. Bruker-OST Wires
- six high-Cp sub-elements in the innermost row
- six high-Cp sub-elements at the six outermost corners
- 24 high-Cp sub-elements in the outermost row
- 24 high-Cp sub-elements in the first two innermost rows and six outermost corners
- 18 high-Cp sub-elements in the first two innermost rows
- 20 high-Cp sub-elements randomly positioned
4.4. Thermal Analysis
4.5. Sensitivity Analysis
5. Results and Discussion
5.1. Model
5.2. Experiment
6. Conclusions
Author Contributions
Funding
Acknowledgments
Conflicts of Interest
References
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Nb3Sn d = 8400 kg m−3 | Cu d = 8960 kg m−3 | Cu-Sn (Sn wt% = 5.46) d = 8850 kg m−3 | Stycast d = 2400 kg m−3 | Gd2O3 d = 7410 kg m−3 | ||||||
---|---|---|---|---|---|---|---|---|---|---|
T | κ | Cp | κ | Cp | κ | Cp | κ | Cp | κ | Cp |
4 K | 174 | 0.41 | 158 | 0.091 | 1.9 | 0.129 | 0.07 | 0.44 | 6.2 | 22 |
6 K | 237 | 0.94 | 237 | 0.226 | 2.9 | 0.194 | 0.11 | 1.70 | 6.2 | 27 |
8 K | 308 | 1.85 | 315 | 0.470 | 3.9 | 0.387 | 0.15 | 3.70 | 6.2 | 29 |
10K | 320 | 3.27 | 394 | 0.856 | 4.9 | 0.968 | 0.19 | 6.20 | 6.2 | 29 |
T | Thermal Diffusivity a [cm2/s] | |||||||||
4 K | 0.505·103 | 1.940·103 | 16.6 | 0.663 | 0.380 | |||||
6 K | 0.300·103 | 1.170·103 | 16.9 | 0.270 | 0.310 | |||||
8 K | 0.198·103 | 0.748·103 | 11.4 | 0.169 | 0.289 | |||||
10 K | 0.116·103 | 0.513·103 | 5.7 | 0.128 | 0.289 |
Nb3Sn | Cu | Cu-Sn | Stycast | |||||
---|---|---|---|---|---|---|---|---|
Thermal Conductivity Variation | −20% | +20% | −20% | +20% | −20% | +20% | −20% | +20% |
Tc dev. at 320 μJ MQE (%) | −0.1 | 0.1 | −0.2 | 0.1 | <0.1 | <0.1 | −1.4 | 1.2 |
Tc dev. at 2300 mJ MQE (%) | −0.3 | 0.2 | −0.6 | 0.5 | <0.1 | <0.1 | −3.5 | 3.3 |
Nb3Sn | Cu | Cu-Sn | Stycast | |||||
Specific Heat Variation | −20% | +20% | −20% | +20% | −20% | +20% | −20% | +20% |
Tc dev. at 320 μJ MQE (%) | −3.7 | 3.3 | −1.7 | 1.6 | −0.3 | 0.3 | −1.1 | 1.0 |
Tc dev. at 2300 mJ MQE (%) | −9.7 | 9.3 | −4.9 | 4.8 | −0.8 | 0.8 | −3.0 | 2.8 |
Nb3Sn | Cu | Cu-Sn | Stycast | Gd2O3 | ||||||
---|---|---|---|---|---|---|---|---|---|---|
Thermal Conductivity Variation | −20% | +20% | −20% | +20% | −20% | +20% | −20% | +20% | −20% | +20% |
Tc dev. at 860 μJ MQE (%) | −0.2 | 0.1 | −0.4 | 0.3 | <0.1 | <0.1 | −0.5 | 0.5 | <0.1 | <0.1 |
Tc dev. at 5200 mJ MQE (%) | −0.6 | 0.5 | −1.5 | 1.1 | <0.1 | <0.1 | −2.0 | 1.9 | <0.1 | <0.1 |
Nb3Sn | Cu | Cu-Sn | Stycast | Gd2O3 | ||||||
Specific Heat Variation | −20% | +20% | −20% | +20% | −20% | +20% | −20% | +20% | −20% | +20% |
Tc dev. at 860 μJ MQE (%) | −1.4 | 1.3 | −0.7 | 0.7 | −0.1 | 0.1 | −0.5 | 0.4 | −5.6 | 4.8 |
Tc dev. at 5200 mJ MQE (%) | −5.5 | 5.3 | −3.1 | 3.1 | −0.4 | 0.4 | −1.8 | 1.7 | −13 | 14 |
Load Angle Variation | ∆θ = −20° | ∆θ = −10° | ∆θ = +10° | ∆θ = +20° |
---|---|---|---|---|
Standard Wire | ||||
Tc dev. at 320 μJ MQE (%) | −0.5 | −0.1 | 0.1 | 0.3 |
Tc dev. at 2300 mJ MQE (%) | −2.0 | −0.6 | 0.6 | 1.1 |
High-Cp Wire | ||||
Tc dev. at 860 μJ MQE (%) | −1.3 | −0.5 | 0.4 | 0.7 |
Tc dev. at 5200 mJ MQE (%) | −4.6 | −1.8 | 1.4 | 2.5 |
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Barzi, E.; Berritta, F.; Turrioni, D.; Zlobin, A.V. Heat Diffusion in High-Cp Nb3Sn Composite Superconducting Wires. Instruments 2020, 4, 28. https://doi.org/10.3390/instruments4040028
Barzi E, Berritta F, Turrioni D, Zlobin AV. Heat Diffusion in High-Cp Nb3Sn Composite Superconducting Wires. Instruments. 2020; 4(4):28. https://doi.org/10.3390/instruments4040028
Chicago/Turabian StyleBarzi, Emanuela, Fabrizio Berritta, Daniele Turrioni, and Alexander V. Zlobin. 2020. "Heat Diffusion in High-Cp Nb3Sn Composite Superconducting Wires" Instruments 4, no. 4: 28. https://doi.org/10.3390/instruments4040028