The purpose of this committee is to grasp the research and development trends in fields where new applications are expected in the future, in addition to the high functionality and systematization of the basic technology of magnetic sensors. Since 2017 we held 10 committees and co-sponsored 8 magnetics study groups. Active exchanges were promoted, such as jointly holding with the C, D, and E departments at each of the three study groups (six times in three years). We also co-sponsored the International Workshop on Magnetic Bio-sensing (November 2018, Yokohama National University) and actively disseminated and collected information. The committee actively discussed and investigated the following considerable items.

In this study, we carried out computer simulations to apply the SSS method to flat multi-channel OPMs with auxiliary sensors and examined the suppression effect of environmental magnetic noise. We assumed that auxiliary sensors are added so that the environmental magnetic noise can be effectively suppressed, and assessed the appropriate position of the sensors. When the auxiliary sensors were circularly aligned with a radius of 50 cm in the plane 40 cm or 30 cm above from the flat multi-channel OPMs with the origin of the SSS method at 10 cm above from the OPMs, the target signal was extracted as an internal component. In addition, in the case of these sensor arrangements, the S/N of 4.3 could be improved to 259.

Ni base alloy, Inconel 600, has high strength and high corrosion resistance, and is therefore widely used for steam generators tubing in power generation plant. During long term plant operation at higher temperature, sensitization occurs along grain boundary, which will induce stress corrosion cracking. The alloy is paramagnetic basically, however it transforms into ferromagnetic along grain boundaries when Cr depletion occurs. Since Cr depletion is attributed to sensitization of the material, nondestructive testing for sensitization using changes in magnetic properties will be possible. Here, Inconel 600 alloy was heat treated at 600℃ from 0 to 400 hours to occur sensitization. Then magnetic field sensor with relatively higher sensitivity scanned over the sensitized specimen. The change in the magnetic field near the surface of specimen is related to the degree of chromium carbides progressing sensitization. The obtained results suggest that scanning with magnetic field sensor is effective to assess sensitization due to heat treatment for Ni base alloy.

In recent years, natural disasters such as earthquakes, torrential rains, heavy snowfalls, and lightning strikes have become a major problem. These disasters are known to cause not only direct damage to infrastructure, but also psychological damage, especially to young people. The reasons for the psychological damage caused by natural disasters are the lack of understanding of the cause of the disaster, and they are difficult to predict. On the other hand, it has been suggested that it is possible to predict the occurrence of earthquakes by using a simple space potential measurement device. In this study, we will measure electromagnetic phenomena using a simple space potential measurement device installed at the KOSEN. As a result, it was found that potential changes occur before a natural disaster. We also applied the results to create an educational device on natural disasters and conducted a questionnaire survey on its effectiveness. As a result, meaningful answers were obtained.

Tailoring is a keyword in the recent development of polymer composite insulation materials. It enables the composites to have desired material properties based on demands in electric power sectors. Computer simulation is an effective approach to tailor new composites and to clarify their characteristics. This paper estimates the material properties of epoxy-based composites containing silica fillers by simulating the composites using a homogenization technique by the finite element method. The rule of mixture can estimate the material properties based on the volume fraction of epoxy resin and fillers. However, it cannot estimate the material properties attributed to composite structures which consist of the epoxy resin and fillers. Therefore, the simulation focuses on a filler diameter distribution in the composites. Moreover, a comparison of material properties calculated in the simulation and measured in the actual composite demonstrates the availability of the simulation.