Chapter 1
Introduction
1.1 Superconductor
Superconductors, the materials that can carry a current without electric resistance,
may be unfamiliar to people. This is because the superconducting state can be realized
only at very low temperatures. It is necessary to cool down a superconductor with
liquid nitrogen at 196 °C to realize the superconducting state, even for the “hightemperature superconductors” discovered in 1986. There is no material that achieves
superconductivity at room temperature. Thus, superconductors are usually placed
within special metallic containers to keep their temperatures low, and hence, people
seldom see them. Superconducting wires are fabricated to carry current, and some
of them are shown in Fig. 1.1.
The role that superconductors play is now gradually increasing around the world.
For example, electromagnets in the Magnetic Resonance Imaging (MRI) systems that
physicians sometimes use in medical examinations are made of superconducting
wires (see Fig. 1.2). The Central Japan Railway Company is planning to connect
Shinagawa in Tokyo and Nagoya, which are separated by 285.6 km, with a 40 min
journey on a Superconducting Magnetic Levitated (SCMAGLEV) Train by the
latter half of the 2020s (see Fig. 1.3). Superconducting magnets are used to levitate and drive the train at very high speed. The prediction of the Higgs boson was
awarded the Nobel Prize in Physics in 2013. The highly developed Japanese technology of superconducting magnets that compose particle accelerators supported
the successful observation of the Higgs boson. Large-scale integrated circuits (LSI)
are now installed in various devices such as computers and home electrical appliances. Large single crystals of high-purity silicon for LSI cannot be made without
strong magnetic fields produced by superconducting magnets. Such a wide variety of
applications for superconducting magnets are owing to their property of no electrical
resistance. For example, the very strong magnetic field produced by superconducting
magnets is useful to levitate heavy trains or to prevent hot melted silicon from moving
by convection and introducing impurities. For MRI, a very stable magnetic field is a
key point.
© The Author(s), under exclusive license to Springer Nature Switzerland AG 2021
T. Matsushita, Superconductivity and Electromagnetism, Springer Series
in Solid-State Sciences 195, https://doi.org/10.1007/978-3-030-67568-4_1
1
Introduction
1.1 Superconductor
Superconductors, the materials that can carry a current without electric resistance,
may be unfamiliar to people. This is because the superconducting state can be realized
only at very low temperatures. It is necessary to cool down a superconductor with
liquid nitrogen at 196 °C to realize the superconducting state, even for the “hightemperature superconductors” discovered in 1986. There is no material that achieves
superconductivity at room temperature. Thus, superconductors are usually placed
within special metallic containers to keep their temperatures low, and hence, people
seldom see them. Superconducting wires are fabricated to carry current, and some
of them are shown in Fig. 1.1.
The role that superconductors play is now gradually increasing around the world.
For example, electromagnets in the Magnetic Resonance Imaging (MRI) systems that
physicians sometimes use in medical examinations are made of superconducting
wires (see Fig. 1.2). The Central Japan Railway Company is planning to connect
Shinagawa in Tokyo and Nagoya, which are separated by 285.6 km, with a 40 min
journey on a Superconducting Magnetic Levitated (SCMAGLEV) Train by the
latter half of the 2020s (see Fig. 1.3). Superconducting magnets are used to levitate and drive the train at very high speed. The prediction of the Higgs boson was
awarded the Nobel Prize in Physics in 2013. The highly developed Japanese technology of superconducting magnets that compose particle accelerators supported
the successful observation of the Higgs boson. Large-scale integrated circuits (LSI)
are now installed in various devices such as computers and home electrical appliances. Large single crystals of high-purity silicon for LSI cannot be made without
strong magnetic fields produced by superconducting magnets. Such a wide variety of
applications for superconducting magnets are owing to their property of no electrical
resistance. For example, the very strong magnetic field produced by superconducting
magnets is useful to levitate heavy trains or to prevent hot melted silicon from moving
by convection and introducing impurities. For MRI, a very stable magnetic field is a
key point.
© The Author(s), under exclusive license to Springer Nature Switzerland AG 2021
T. Matsushita, Superconductivity and Electromagnetism, Springer Series
in Solid-State Sciences 195, https://doi.org/10.1007/978-3-030-67568-4_1
1