BS EN IEC 61788 discusses superconductivity. BS EN IEC 61788‑17 is the seventeenth part of multi-series BS EN IEC 61788 and discusses local critical current density and its distribution in large-area superconducting films.
BS EN IEC 61788‑17 specifies the measurements of the local critical current density (Jc) 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 Jc at liquid nitrogen temperatures by an electric-field criterion and obtain current-voltage characteristics from its frequency dependence. This technique intrinsically measures the critical sheet current that is the product of Jc and the film thickness d. The range and measurement resolution for Jcd of HTS films are as follows
BS EN IEC 61788‑17 on Superconductivity (Part 17: Electronic characteristic measurements — Local critical current density and its distribution in large-area superconducting films) is applicable to:
Over thirty years after their discovery in 1986, high-temperature superconductors are now finding their way into products and technologies that will revolutionize information transmission, transportation, and energy. Large-area superconducting thin films have been developed for use in microwave devices [2]. They are also considered for use in emerging superconducting power devices, such as resistive type superconducting fault-current limiters (SFCLs) [3] [4] [5], superconducting fault detectors used for superconductor-triggered fault current limiters [6] [7] and persistent-current switches used for persistent-current HTS magnets [8] [9]. The critical current density Jc is one of the key parameters that describe the quality of large-area HTS films.
The conventional methods are not accurate because they have not considered the electric-field E criterion of the Jc measurement [14] [15] and sometimes use an inappropriate criterion to determine the threshold current Ith from which Jc is calculated.
BS EN IEC 61788‑17 provides you an inductive method using third-harmonic voltages. A standard method to precisely measure Jc with an electric-field criterion by detecting U3 and obtaining the n-value(index of the power-law E-J characteristics) by measuring Ith precisely at various frequencies[14] [15] [18] [19]. This method not only obtains precise Jc values but also facilitates the detection of degraded parts in inhomogeneous specimens because the decline of n-value is
more noticeable than the decrease of Jc in such parts. It is noted that BS EN IEC 61788‑17 method is excellent for assessing homogeneity in large-area HTS films, although the relevant parameter for designing microwave devices is not Jc, but the surface resistance.
BS EN IEC 61788‑17:2021 supersedes BS EN 61788‑17:2013, which is withdrawn. BS EN IEC 61788‑17:2021 includes some technical changes with respect to BS EN 61788‑17:2013. These include:
A simple method to calculate theoretical coil coefficient k is described in 6.2.1.IEC 61788-17 Ed.2.0