174
Afterword
This group was the first group worldwide to complete the theoretical framework
of electromagnetic phenomena based on the critical state model and investigate the
flux pinning mechanism in 1967. In addition, they designed the superconducting
magnetic energy storage (SMES) system and classified such systems based on their
stored energy and power in the early 1970s. In such a situation, his research was
naturally directed to the electromagnetic properties and flux pinning phenomena
relevant to applied superconductivity. Thus, the author received a doctoral degree for
his research on the flux pinning mechanism.
In the course of the research in this group, the longitudinal magnetic field effect
was investigated by other scientists, and the author was attracted to this peculiar
phenomenon. The first analysis by the author on this effect was on the flux invasion
into a superconducting cylinder, as shown in Appendix A.10. The author recognized the fundamental points on this effect, and then, he read many associated
papers. Finally, he found that the misunderstanding of this effect in the 1970s was
essentially based on a wrong interpretation of the theory by Josephson on general
electromagnetic features. Then, each problem was solved step by step.
High temperature superconductivity was discovered in 1986. Soon after, almost
all of the research on superconductivity was concentrated on the new materials. The
author moved from Kyushu University to Kyushu Institute of Technology in 1990.
Although the research on flux pinning phenomena and the longitudinal magnetic field
effect in metallic superconductors was still interesting, the author also mainly investigated the electromagnetic phenomena, especially the flux creep, of high temperature
superconductors and established the theory of collective flux creep and flow. In this
theory the flux bundle size is assumed to be determined by the principle of minimum
energy dissipation. This was based on his experience in studying the longitudinal
magnetic field effect.
In the meantime, the author was asked to publish “Flux Pinning and Electromagnetic Phenomena in Superconductors” by Sangyo Tosho Co. in Japan. Then,
the coherent potential approximation theory on the flux pinning mechanism was
completed, since it was the main point in this book. Thus, the threshold problem in
the summation theory that had been argued for a long time was solved. The complicated theory of the longitudinal magnetic field effect was also arranged in order for
easy understanding.
The author was occasionally occupied by the administrative work of Kyushu
Institute of Technology from the end of the 20th century to the beginning of the 21st
century, so it was quite difficult to continue research in this period. There was a time
to think over the difficult problem, however, of spreading the acquired knowledge
on the longitudinal magnetic field effect to scientists around the world. Unfortunately, the electromagnetic phenomena in superconductors are familiar to only a
small fraction of scientists, and almost no scientists in other fields will know about
the longitudinal magnetic field effect. In addition, whereas this is a fundamental effect
of electromagnetism, the section on electromagnetism has disappeared from the main
journals on physics. Thus, there is no way to directly send a message to scientists
around the world. The author then felt the necessity to familiarize young people
with superconductivity. Fortunately, the author had taught the fundamental magnetic
Afterword
This group was the first group worldwide to complete the theoretical framework
of electromagnetic phenomena based on the critical state model and investigate the
flux pinning mechanism in 1967. In addition, they designed the superconducting
magnetic energy storage (SMES) system and classified such systems based on their
stored energy and power in the early 1970s. In such a situation, his research was
naturally directed to the electromagnetic properties and flux pinning phenomena
relevant to applied superconductivity. Thus, the author received a doctoral degree for
his research on the flux pinning mechanism.
In the course of the research in this group, the longitudinal magnetic field effect
was investigated by other scientists, and the author was attracted to this peculiar
phenomenon. The first analysis by the author on this effect was on the flux invasion
into a superconducting cylinder, as shown in Appendix A.10. The author recognized the fundamental points on this effect, and then, he read many associated
papers. Finally, he found that the misunderstanding of this effect in the 1970s was
essentially based on a wrong interpretation of the theory by Josephson on general
electromagnetic features. Then, each problem was solved step by step.
High temperature superconductivity was discovered in 1986. Soon after, almost
all of the research on superconductivity was concentrated on the new materials. The
author moved from Kyushu University to Kyushu Institute of Technology in 1990.
Although the research on flux pinning phenomena and the longitudinal magnetic field
effect in metallic superconductors was still interesting, the author also mainly investigated the electromagnetic phenomena, especially the flux creep, of high temperature
superconductors and established the theory of collective flux creep and flow. In this
theory the flux bundle size is assumed to be determined by the principle of minimum
energy dissipation. This was based on his experience in studying the longitudinal
magnetic field effect.
In the meantime, the author was asked to publish “Flux Pinning and Electromagnetic Phenomena in Superconductors” by Sangyo Tosho Co. in Japan. Then,
the coherent potential approximation theory on the flux pinning mechanism was
completed, since it was the main point in this book. Thus, the threshold problem in
the summation theory that had been argued for a long time was solved. The complicated theory of the longitudinal magnetic field effect was also arranged in order for
easy understanding.
The author was occasionally occupied by the administrative work of Kyushu
Institute of Technology from the end of the 20th century to the beginning of the 21st
century, so it was quite difficult to continue research in this period. There was a time
to think over the difficult problem, however, of spreading the acquired knowledge
on the longitudinal magnetic field effect to scientists around the world. Unfortunately, the electromagnetic phenomena in superconductors are familiar to only a
small fraction of scientists, and almost no scientists in other fields will know about
the longitudinal magnetic field effect. In addition, whereas this is a fundamental effect
of electromagnetism, the section on electromagnetism has disappeared from the main
journals on physics. Thus, there is no way to directly send a message to scientists
around the world. The author then felt the necessity to familiarize young people
with superconductivity. Fortunately, the author had taught the fundamental magnetic