One hundred years have passed since the discovery of superconductivity. Over this time, the science, especially in the area of physics, relating to superconductivity has improved dramatically. However, no appreciable progress has been made in the education of superconductivity in relation to primary electromagnetism. A superconductor is a unique material in which Ohm's law is not applicable to the flow of electric current. If this physical point is carefully considered, a new perspective on electromagnetic properties emerges. In this series of lectures, electromagnetic phenomena in superconductors are examined from various aspects. The first lecture deals primarily with the magnetic phenomena occurring in the vicinity of superconductors while they are in the Meissner-Ochsenfeld state, showing perfect diamagnetism. It is shown that by introducing this magnetic phenomenon to the present E-B analogy, the style of teaching primary electromagnetism can be dramatically changed. In accordance with this analogy, it would even have been possible to predict the existence of superconductors in the 19th century after the formulation of the Maxwell theory. This kind of discussion reinforces the E-B analogy. The introduction of superconductivity makes it possible to directly derive the magnetic energy through a mechanical action working against the magnetic force. In contrast, the magnetic energy can be derived only after teaching electromagnetic induction in existing textbooks. Other merits of introducing superconductivity are also discussed.
It is observed that the measured critical currents of cable-in-conduit (CIC) conductors for ITER TF coils become lower than expected due to the unbalanced current distribution that is caused by contact resistance between the strands and the Copper (Cu) sleeves in CIC conductor joints. In order to evaluate the contact length, we identify the three-dimensional positions of all strands in the CIC conductor, and then measure the contact number and lengths of strands that appear on the surface of the cable to contact with the Cu sleeves. It is found that some strands do not appear on the surface of the cable, and the contact lengths are widely distributed with a large standard deviation. We develop a numerical code that simulates strand positions in the CIC, and then compare the analyzed contact strand number and contact length with measured ones. It is found that the results are in agreement, and hence the code can be used to evaluate the contact parameters. After varying the twist pitches of the sub-cables, we show that all strands appear on the cable surface and have contact lengths with small standard deviation. It is found that the twist pitches are a key parameter for optimization of the contact resistance.