This part of IEC 61 788 specifies the measurements of the local critical current density (J c ) and its distribution in large-area high-temperature superconducting (HTS) films by an inductive method using third-harmonic voltages. The most important consideration for precise measurements is to determine J c at liquid nitrogen temperatures by an electric-field criterion and obtain current-voltage characteristics from its frequency dependence. Although it is possible to measure J c in applied DC magnetic fields [20] [21 ], the scope of this document is limited to the measurement without DC magnetic fields.
This technique intrinsically measures the critical sheet current that is the product of J c and the film thickness d. The range and measurement resolution for J c d of HTS films are as follows.
– J c d: from 200 A/m to 32 kA/m (based on results, not limitation).
– Measurement resolution: 1 00 A/m (based on results, not limitation).
