Theoretical analysis on ac susceptibility measurements of superconductor tapes

Chen, Du-Xing; Sun, Yu; Li, Shuo; Fang, Jin

doi:10.1088/1361-6501/28/2/025003

Cited by 10 publications

(6 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, the µ 0 H m value which gives maximum value of the Q m0 /(µ 0 H m ) 2 curve increases with decreasing temperature. We attribute it to the temperature-dependent effective penetration field [12,26,43], which is proportional to the critical current density of the superconductor [12,44]. With decreasing temperature, the measured Q m0 /(µ 0 H m ) 2 values become larger at high magnetic fields, which is due to the increase of critical current of the coated conductor at lower temperature.…”

Section: Frequency-dependence Of Dynamic Resistancementioning

confidence: 91%

Total loss measurement and simulation in a REBCO coated conductor carrying DC current in perpendicular AC magnetic field at various temperatures

Sun

Sidorov

et al. 2021

Supercond. Sci. Technol.

Self Cite

View full text Add to dashboard Cite

In many high-temperature superconducting (HTS) applications, HTS coated conductors carry DC currents under external AC magnetic fields. There are two AC loss mechanisms in this situation: magnetization loss due to the external magnetic field and dynamic loss due to the interaction between the DC current and the external magnetic field. The sum of these two loss components is referred to as total loss. In this work, the total loss in a 4 mm wide REBCO coated conductor is measured under perpendicular AC magnetic fields up to 105 mT at 77 K, 70 K, and 65 K, with reduced DC current level, i (I dc/I c0), from 0.025 to 0.98, where I dc is the transport DC current value and I c0 is the self-field critical current of the coated conductor at each temperature. The experimental results show a good quantitative agreement with an analytical equation for each loss component, as well as 2D finite element modelling (FEM) results from H -formulation. For any given temperature, we observe that the total loss is mostly dominated by magnetization loss at i< 0.2, while dynamic loss makes a comparable, even greater contribution to total loss at i > 0.5. Electromagnetic analysis from the FEM modelling shows the evolution process of total loss, where the dynamic loss region and magnetization loss region vary across the conductor width at high magnetic fields or high DC current level. The simulation results also reveal the superposition of (positive) DC current and the anti-parallel (negative) shielding current, which occurs at high DC current level. The superposition drives the current density of one conductor edge to subcritical stage, and it leads to one-sided loss generation in each half-cycle. Our results provide a valuable reference for total loss behaviours in REBCO coated conductors.

show abstract

Section: Frequency-dependence Of Dynamic Resistancementioning

confidence: 91%

Total loss measurement and simulation in a REBCO coated conductor carrying DC current in perpendicular AC magnetic field at various temperatures

Sun

Sidorov

et al. 2021

Supercond. Sci. Technol.

Self Cite

View full text Add to dashboard Cite

show abstract

“…( 10)] using the geometry dimensions of the Fujikura wire. Earlier research pointed out that the maximum value of χ /χ 0 occurs at B p [16], [34].…”

Section: Reduction Of Eddy Current Loss In Copper Strips Next To Supe...mentioning

confidence: 98%

Shielding Effect of (RE)Ba₂Cu₃O_7-d-Coated Conductors on Eddy Current Loss of Adjacent Metal Layers Under AC Magnetic Fields With Various Orientations

Sun

Long

Sidorov

et al. 2021

IEEE Trans. Appl. Supercond.

Self Cite

View full text Add to dashboard Cite

Ba 2 Cu 3 O 7-d (REBCO) coated conductors are becoming a preferred wire choice for many potential high temperature superconducting (HTS) applications, where additional metal layers are usually attached to the REBCO conductors to improve reliability and stability. In such cases, the eddy current loss in the metal layers is affected by the magnetic field shielding by adjacent REBCO coated conductors. Here we present the ac loss measurement and simulation results in three copper-superconductor stacks comprising a 10-mm-wide Fujikura-coated conductor with one, two, and four 0.1-mm-thick, 10-mm-wide copper strips, under various applied magnetic field angles (defined by the angle between the applied magnetic field and the wide face of the superconductor) from 15°to 90°at 77 K. The amplitude of the magnetic field is up to 100 mT. The shielding effect, which reduces the eddy current loss in the metal layers stacked with a superconductor layer, increases with decreasing field angles, due to the change of the effective penetration field at the different field angles. The eddy current loss in the copper strips in the copper-superconductor stacks under the magnetic fields with various orientations is dominated by the perpendicular magnetic field component.

show abstract

“…The principle of magnetization loss measurement is to detect the magnetization (M) of a sample which is exposed to an AC magnetic field (B). Therefore, a magnet generating uniform magnetic fields, and a measuring coil for detecting the change rate of magnetization (𝑑𝐌/𝑑𝑡) are essential components in the measurements [30,99,102,[125][126][127] . Following this, two commercially available instruments are developed for precise magnetization measurements, i.e., superconducting quantum interference devices (SQUIDs) and vibrating-sample magnetometers (VSMs) [30] .…”

Section: Ac Loss Measurementsmentioning

confidence: 99%

“…The imaginary AC susceptibility  ² 100 was derived from magnetization loss results in Figure 4-13 using Eq. (4.17) [102,167,168] . The initial susceptibility 0 was calculated from Eq.…”

Section: Ac Loss In Copper-superconducting Stack At Various Magnetic ...mentioning

confidence: 99%

“…But the threshold magnetic field expressions are different and listed as follows. Both Bth1 and Bth2 can be referred as Bth: Bth1 is derived by Z. Jiang et al [100] based on the effective penetration field of the superconducting strip [101,102] ; Bth2 is proposed by G. P. Mikitik et al using the Brandt method [32] . Then, the dynamic resistance in the superconducting strip under a perpendicular magnetic field is given by Eqs.…”

mentioning

confidence: 99%

See 1 more Smart Citation

AC Loss Research of REBCO High-Tc Superconductors Carrying a DC Current in an AC Magnetic Field

Sun¹

View full text Add to dashboard Cite

AbstractREBCO (REBa2Cu3O7-d, RE stands for rare earth) high temperature superconducting (HTS) coated conductors (CCs) have become the preferred wire choice for HTS applications due to their high current carrying capacity and advanced mechanical properties. In many HTS applications such as HTS synchronous motors, HTS flux pumps and HTS persistent current switches, REBCO CCs, stacks and coils carry DC currents in an AC magnetic field environment, generating AC loss comprising of dynamic loss component arising from dynamic resistance and the magnetization loss component due to the shielding currents. AC loss behaviours of commercial-available REBCO CCs in such operating conditions haven’t been fully explored with the most prominent research question of how the AC loss and each loss component evolve and behave in the single REBCO CC, REBCO stacks and REBCO coils at different temperatures with various operating conditions. Other interesting open questions are also put forward to underpin relevant engineering applications: how the shielding effect of REBCO CCs influences the eddy current loss in adjacent copper layers at various field orientation; what kind of inherent correlation exists between the asymmetric field-orientation-dependent critical current characteristics and the magnetization loss behaviors; and how the loss behaviours in REBCO stacks and coils differentiate from the REBCO CC; what’s the difference between the REBCO racetrack coil and the REBCO double pancake coil regarding characteristics of the critical current, magnetization loss, dynamic resistance and AC loss under the condition of the combined DC current with the AC magnetic field. This thesis aims to underpin the REBCO HTS applications and reveal the underlying AC loss mechanism through systematically experimental and numerical research on AC loss and dynamic resistance in REBCO CCs, REBCO stacks and REBCO coils that operate at various electromagnetic conditions and temperatures (65 K ~ 77 K). This research has revealed many new phenomena in the loss evolution process and reached illuminating conclusions. We uncover the shielding effect of REBCO CCs under various field orientations is dominated by the perpendicular magnetic field component, and so does the reduced eddy current loss in the adjacent copper layers of the copper-superconductor stacks. When exploring the role of asymmetric field-orientation-dependent critical current on the magnetization loss of REBCO CCs, we reveal that the asymmetry of critical current about the ab-peak within the 360 full-field-angle range causes differences in magnetization loss values at the field angles which are in mirror symmetry relative to the ab-plane. Furthermore, it is surprising and contradicting to find that magnetization loss at any given field orientation is unequal between the positive and the negative half-field cycle due to the asymmetry of critical current upon the field reversal. The asymmetric field-orientation dependence of both critical current and magnetization loss becomes more obvious with the increasing magnetic field amplitudes and the decreasing temperatures. The complicated AC loss evolution process in REBCO CCs under AC magnetic fields and DC currents is probed by demonstrating the striking behaviours: the dynamic loss region and magnetization loss region vary across the conductor width at high magnetic fields or high DC current levels; the (positive) DC current is superposed with the anti-parallel (negative) shielding current at high DC current levels that approaching to the self-critical current, which drives the local current density of one conductor edge to the subcritical stage and leads to one-sided loss generation in each half-cycle. At the liquid nitrogen temperature range, experimental and simulation results exemplify that the AC loss is mostly dominated by magnetization loss when DC current is less than 20% critical current, while dynamic loss makes a comparable, even greater contribution to AC loss when DC current is larger than 50% critical current. The dynamic resistance shows an obvious frequency dependence due to the heating accumulation at high field amplitudes, high DC current levels and high operating temperatures, which provides a useful reference for the application designs of HTS flux pumps and HTS persistent current switches. Compared with the single REBCO CC, the onset of dynamic resistance/loss in REBCO stacks and REBCO coils is much slower, and the contribution of the dynamic loss component to the AC loss is also much smaller. Dynamic loss in the stack becomes greater than the magnetization loss when the DC current is larger than 70% critical current, while always less than the magnetization loss in the coils when the AC magnetic field is less than 0.1 T. We also conclude that the critical current, magnetization loss and dynamic resistance/loss per unite length in the REBCO racetrack coil is slightly larger than those of the REBCO pancake coil. The main contribution of this work is to reveal the complex AC loss mechanism in REBOC CCs, stacks and coils carrying DC currents in the AC magnetic field and characterize the loss behaviours via solid experimental measurements and numerical simulations. Meanwhile, the magnetization loss as the dominant loss component is further explored concerning its shielding effect and the asymmetric critical current characteristics. This work exemplifies the underlying nature of AC loss behaviours, providing a valuable reference to understand the loss mechanism and to underpin relevant HTS applications.

show abstract

Theoretical analysis on ac susceptibility measurements of superconductor tapes

Cited by 10 publications

References 22 publications

Total loss measurement and simulation in a REBCO coated conductor carrying DC current in perpendicular AC magnetic field at various temperatures

Total loss measurement and simulation in a REBCO coated conductor carrying DC current in perpendicular AC magnetic field at various temperatures

Shielding Effect of (RE)Ba₂Cu₃O_7-d-Coated Conductors on Eddy Current Loss of Adjacent Metal Layers Under AC Magnetic Fields With Various Orientations

AC Loss Research of REBCO High-Tc Superconductors Carrying a DC Current in an AC Magnetic Field

Contact Info

Product

Resources

About

Theoretical analysis on ac susceptibility measurements of superconductor tapes

Cited by 10 publications

References 22 publications

Total loss measurement and simulation in a REBCO coated conductor carrying DC current in perpendicular AC magnetic field at various temperatures

Total loss measurement and simulation in a REBCO coated conductor carrying DC current in perpendicular AC magnetic field at various temperatures

Shielding Effect of (RE)Ba2Cu3O7-d-Coated Conductors on Eddy Current Loss of Adjacent Metal Layers Under AC Magnetic Fields With Various Orientations

AC Loss Research of REBCO High-Tc Superconductors Carrying a DC Current in an AC Magnetic Field

Contact Info

Product

Resources

About

Shielding Effect of (RE)Ba₂Cu₃O_7-d-Coated Conductors on Eddy Current Loss of Adjacent Metal Layers Under AC Magnetic Fields With Various Orientations