This method is intended for use with superconductor specimens that have critical current less than 300 A and n-values larger than 5 under standard test conditions: the test specimen is immersed in liquid nitrogen bath at ambient pressure without external magnetic field during the testing. Deviations from this test method that are allowed for routine tests and other specific restrictions are given in this document. ]]>

This method is intended for use with superconductor specimens that have critical current less than 300 A and n-values larger than 5 under standard test conditions: the test specimen is immersed in liquid nitrogen bath at ambient pressure without external magnetic field during the testing. Deviations from this test method that are allowed for routine tests and other specific restrictions are given in this document.]]>

IEC 61788-7:2020 describes measurement of the surface resistance (Rs) of superconductors at microwave frequencies by the standard two-resonator method. The object of measurement is the temperature dependence of Rs at the resonant frequency. The applicable measurement range of Rs for this method is as follows:

- Frequency: 8 GHz < f < 30 GHz

- Measurement resolution: 0,01 m Ω at 10 GHz

The Rs data at the measured frequency, and that scaled to 10 GHz, assuming the f 2 rule for comparison, is reported. This third edition cancels and replaces the second edition, published in 2006. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:

a) informative Annex B, relative combined standard uncertainty for surface resistance measurement has been added;

b) precision and accuracy statements have been converted to uncertainty;

c) reproducibility in surface resistant measurement has been added.

IEC 61788-7:2020 describes measurement of the surface resistance (Rs) of superconductors at microwave frequencies by the standard two-resonator method. The object of measurement is the temperature dependence of Rs at the resonant frequency. The applicable measurement range of Rs for this method is as follows:

- Frequency: 8 GHz < f < 30 GHz

- Measurement resolution: 0,01 m Ω at 10 GHz

The Rs data at the measured frequency, and that scaled to 10 GHz, assuming the f 2 rule for comparison, is reported. This third edition cancels and replaces the second edition, published in 2006. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:

a) informative Annex B, relative combined standard uncertainty for surface resistance measurement has been added;

b) precision and accuracy statements have been converted to uncertainty;

c) reproducibility in surface resistant measurement has been added.

IEC 61788-4:2020 specifies a test method for the determination of the residual resistance ratio (RRR) of Nb-Ti and Nb3Sn composite superconductors with Cu, Cu-Ni, Cu/Cu-Ni and Al matrix in a strain-free condition and zero external magnetic field. This method is intended for use with superconductor specimens that have a monolithic structure with rectangular or round cross-section, RRR value less than 350, and cross-sectional area less than 3 mm^{2}. In the case of Nb3Sn, the specimens have received a reaction heat-treatment. This fifth edition cancels and replaces the fourth edition published in 2016. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:

a) change in the suitable distance of voltage taps on the specimen for reliable measurement,

b) new report on the result of the round robin test of the residual resistance ratio of Nb3Sn superconductors that proves the validity of the measurement method in this standard,

c) revision of the confusing definitions of the copper ratio and copper fraction.

IEC 61788-4:2020 specifies a test method for the determination of the residual resistance ratio (RRR) of Nb-Ti and Nb3Sn composite superconductors with Cu, Cu-Ni, Cu/Cu-Ni and Al matrix in a strain-free condition and zero external magnetic field. This method is intended for use with superconductor specimens that have a monolithic structure with rectangular or round cross-section, RRR value less than 350, and cross-sectional area less than 3 mm^{2}. In the case of Nb3Sn, the specimens have received a reaction heat-treatment. This fifth edition cancels and replaces the fourth edition published in 2016. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:

a) change in the suitable distance of voltage taps on the specimen for reliable measurement,

b) new report on the result of the round robin test of the residual resistance ratio of Nb3Sn superconductors that proves the validity of the measurement method in this standard,

c) revision of the confusing definitions of the copper ratio and copper fraction.

a) change in the suitable distance of voltage taps on the specimen for reliable measurement,

b) new report on the result of the round robin test of the residual resistance ratio of Nb3Sn superconductors that proves the validity of the measurement method in this standard,

c) revision of the confusing definitions of the copper ratio and copper fraction. ]]>

IEC 61788-4:2020 specifies a test method for the determination of the residual resistance ratio (RRR) of Nb-Ti and Nb3Sn composite superconductors with Cu, Cu-Ni, Cu/Cu-Ni and Al matrix in a strain-free condition and zero external magnetic field. This method is intended for use with superconductor specimens that have a monolithic structure with rectangular or round cross-section, RRR value less than 350, and cross-sectional area less than 3 mm^{2}. In the case of Nb3Sn, the specimens have received a reaction heat-treatment. This fifth edition cancels and replaces the fourth edition published in 2016. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:

a) change in the suitable distance of voltage taps on the specimen for reliable measurement,

b) new report on the result of the round robin test of the residual resistance ratio of Nb3Sn superconductors that proves the validity of the measurement method in this standard,

c) revision of the confusing definitions of the copper ratio and copper fraction.

- Frequency: 8 GHz < f < 30 GHz

- Measurement resolution: 0,01 m Ω at 10 GHz

The Rs data at the measured frequency, and that scaled to 10 GHz, assuming the f 2 rule for comparison, is reported. This third edition cancels and replaces the second edition, published in 2006. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:

a) informative Annex B, relative combined standard uncertainty for surface resistance measurement has been added;

b) precision and accuracy statements have been converted to uncertainty;

c) reproducibility in surface resistant measurement has been added. ]]>

IEC 61788-7:2020 describes measurement of the surface resistance (Rs) of superconductors at microwave frequencies by the standard two-resonator method. The object of measurement is the temperature dependence of Rs at the resonant frequency. The applicable measurement range of Rs for this method is as follows:

- Frequency: 8 GHz < f < 30 GHz

- Measurement resolution: 0,01 m Ω at 10 GHz

The Rs data at the measured frequency, and that scaled to 10 GHz, assuming the f 2 rule for comparison, is reported. This third edition cancels and replaces the second edition, published in 2006. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:

a) informative Annex B, relative combined standard uncertainty for surface resistance measurement has been added;

b) precision and accuracy statements have been converted to uncertainty;

c) reproducibility in surface resistant measurement has been added.

The test method is intended for use with superconductors that have a critical current less than 300 A and an n-value larger than 5.]]>

- using the word "uncertainty" for all quantitative (associated with a number) statistical expressions and eliminating the quantitative use of "precision" and "accuracy". Key words: superconductivity, TC90 ]]>

- extending the applications of the pickup coil method to the a.c. loss measurements in metallic and oxide superconducting wires with a round cross section at liquid helium temperature,

- using the word "uncertainty" for all quantitative (associated with a number) statistical expressions and eliminating the quantitative use of "precision" and "accuracy". Key words: superconductivity, TC90 ]]>