IEC 61788-7-2020 SUPERCONDUCTIVITY – Part 7: Electronic characteristic measurements – Surface resistance of high-temperature superconductors at microwave frequencies.
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050-81 5 apply.
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4 Requirements
The R s of a superconductor film shall be measured by applying a microwave signal to a dielectric resonator with the superconductor film specimen and then measuring the attenuation of the resonator at each frequency. The frequency shall be swept around the resonant frequency as the centre, and the attenuation–frequency characteristics shall be recorded to obtain the Q- value, which corresponds to the loss.
The target relative combined standard uncertainty of this method is less than 20 % for the measurement temperature range from 20 K to 80 K.
It is the responsibility of the user of this document to establish appropriate safety and health practices and to determine the applicability of regulatory limitations prior to use. Hazards exist in this type of measurement. The use of a cryogenic system is essential to cool the superconductors to allow transition into the superconducting state. Direct contact of skin with cold apparatus components can cause immediate freezing, as can direct contact with a spilled cryogen. The use of an RF generator is also essential to measure high-frequency properties of materials. If its power is too high, direct contact to human bodies can cause an immediate burn.
5 Apparatus
5.1 Measurement system Figure 1 shows a schematic diagram of the system required for the microwave measurement. The system consists of a network analyzer system for transmission measurement, a measurement apparatus, and a thermometer for monitoring the measuring temperature. An incident power generated from a suitable microwave source such as a synthesized sweeper is applied to the dielectric resonator fixed in the measurement apparatus. The transmission characteristics are shown on the display of the network analyzer. The measurement apparatus is fixed in a temperature-controlled cryocooler.IEC 61788-7 pdf download.