Review on thermal-related measurement methods for superconducting devices and prospect for high-speed maglev transportation application

High-temperature superconducting (HTS) bulks can not only be self-stable when levitated above a permanent magnet (PM) but also can be used as quasi PM with higher magnetic energy product due to their magnetic flux pinning characteristics. Therefore, HTS bulks have wide application potentials in maglev trains, maglev bear-ings, flywheel energy storage, drug delivery, and high field magnets. In the external magnetic field of common application scenarios, HTS bulks have no external input current, so it is difficult to achieve the overall quench. However, local quenching in the bulk is still possible in the harsh fluctuating external field environment. Although it is difficult to reach the total quench, its critical parameters like Jc will inevitably deteriorate, which may collapse the application system. Therefore, in contrast to superconducting wires and tapes that are more concerned with quench detection, HTS bulks with a 3D volume effect are more focused on internal sensitive temperature locations, the impacts of volume and scale, and the coupling influence on application parameters such as magnetism and force. Therefore, for efficient thermal-related measurement of HTS bulk applications, this paper investigates and discusses 12 commonly-used temperature measurement or quench detection meth-ods in all superconducting application fields. These methods primarily refer to the current quench detection technologies used in HTS tapes and wires. From the standpoint of practical temperature measurement require-ments of HTS bulks and technological limitations of maglev application scenarios, working characteristics and service conditions of the 12 methods, and 4 temperature detection methods are selected through a comprehen-sive understanding and comparison of basic principles. They are expected to be used in real-time monitoring and early warning schemes for onboard superconducting levitation devices of HTS maglev transportation or other applications in the future.