GB/T 39843-2021 in English
VALIDElectronic characteristic measurements—Local critical current density and its distribution in large-area superconducting films
- Issued on:2021-03-09
- Implemented on:2021-10-01
- File Format:PDF
- Delivery:Via email within 5 business days
$612.00
《GB/T 39843-2021电子学特性测量 大面积超导膜的局域临界电流密度及其分布》由TC265（全国超导标准化技术委员会）归口，主管部门为中国科学院。
Introduction
Interpretation of the core content of the standard
This standard is equivalent to IEC6178817:2013, which stipulates the technical specifications for measuring the critical current density (Jc) of large-area high-temperature superconducting (HTS) films by the third harmonic voltage induction method. The focus is on solving the 10%-20% error problem caused by unclear electric field criteria in traditional measurements.
Key Technical Principles
| Measurement Parameters | Traditional Method | This Standard Method |
|---|---|---|
| Criteria Basis | Voltage Threshold | Electric Field Strength E Criteria(e.g. 100μV/m) |
| Measurement Method | Single Frequency Measurement | Multi-Frequency Correlated Measurement(2-4 Frequencies) |
| Key Parameters | Jc Only | Jc+n-value(EJ Characteristic Index) |
Typical application case: A YBCO superconducting film, under the criterion of Ec=100μV/m, obtained Jc=2.4×1010A/m2 by 2kHz/8kHz dual-frequency measurement, n=26.5, relative uncertainty <5%
Requirements for measurement device
Core components:
- Sample coil: flat copper coil with outer diameter 2-5mm (such as D2=4.2mm, 400 turns)
- Cancellation system: Cancellation coil with large Jcd superconducting film (to reduce harmonic noise)
- Spacing control: Z1=200μm±20μm (0.2MPa clamping force is required to prevent liquid nitrogen penetration)
Key parameters:
- Jcd measurement range: 200A/m~32kA/m
- Resolution: ≥100A/m
Standardized measurement process
- Calibration stage:
- Transmission method to measure and calibrate the EJ characteristics of the microbridge of the wafer (n≈20-24)
- Multi-frequency U3 measurement to determine the experimental coil coefficient k' (e.g. 82.2mm-1±2.4mm-1)
- Sample testing:
- Using constant inductance criterion 2πLc=U3/fI0=2μΩ·s
- Scanning measurement to obtain Jc distribution diagram (spatial resolution ≈ coil diameter)
Note:Edge measurement requires that the outer edge of the coil be ≥0.5mm away from the edge of the film (a coil with an outer diameter of 5mm can measure a minimum film width of 6mm)
Uncertainty control
Main error sources:
- Coil spacing deviation: When ΔZ1=20μm, the impact is ≈2.6% (Class B)
- Bean model simplification: leads to E underestimated by ≈3.8% (when n=25)
- Calibration wafer non-uniformity: Contributes to the main Type A uncertainty (≈1%)
Combined uncertainty:Jc absolute value <10%, uniformity assessment <5%
Loading PDF document...
Error loading PDF. Please make sure the file is valid and try again.
We also recommend
-
GB/T 41640-2022 in English
Critical current measurement—Measurement of critical current and its uniformity along the length of 2G-HTS long tapes
2022-10-12
