achieving this dream: from primitive dugout canoes to the sailboats of the Medieval
Era, the steam ships of the modern era, and today’s high-speed passenger ships,
boats have been improved in shape and function over time to suit the purposes of
long-term travel. Early boats moved purely by human-generated force; after that
came boats that harnessed the power of the wind. Today, most boats are driven by
motors and propellers. Recently, however, a historic form of boat has been under
development—one with propeller-free, electronic propulsion (Crow et al. 1991).
The electronic propulsion system on this propeller-free boat is based on the
Fleming Left Hand Rule, one of the basic principles of electromagnetics. It became
the subject of much research in the U.S. after first being proposed by Rice in the
1960s, but numerous technological difficulties arise, and no satisfactory results were
achieved. In 1976, the first real development of a propeller-free boat came when a
Kobe University team led by Sachi devised a model that used a superconductor for
an electrical propulsion device. In 1991, Japan’s Shipbuilding Industry Foundation
and Mitsubishi Heavy Industries held a launch ceremony for the world’s first
superconductor-powered electrical ship, the Yamato-1. The ship was just a test
vessel measuring 30 m and 280 tons, with a design speed of 8 knots (around
15 km) and a capacity of 10 people. Once a superconducting coil and superconductor magnetic shielding technology are developed and issues are resolved with
alternative refrigerants for superconducting materials, the future may bring development of a superconducting ship capable of traveling at over 100 knots (about
180 km) without a propeller. (Konishi 1989).
A. What Is Superconductivity?
What is the superconductivity that has made these things possible? Typically, the
term “conductor” is used to refer to materials through which an electric current
travels easily, and “insulator” to those in which it does not. As ordinary metals like
copper increase in temperature, they lose resistance as their atoms experience lattice
vibration. When a current flows, resistance arises as a result of this lattice vibration,
and electricity is lost. (In other words, less than 100% of electricity is received.)
When the metal’s temperature is lowered, its electrical resistance decreases. As it
reaches a certain point close to an absolute temperature of 0 K (−273 °C), some
inherent electrical resistance remains in the metal despite any further cooling. In
some materials, however, electrical resistance suddenly falls to zero at a certain
temperature. This phenomenon is known as superconductivity (Wu et al. 1987).
Superconductivity was first discovered in 1911 by the Dutch physicist Kamerlingh Onnes. In 1908, he succeeded in compressing helium gas to produce liquid
helium at an absolute temperature of 4 K (−269 °C). He then used this to cool
substances to an absolute temperature close to 0 K (−273 °C). As he was studying
the relationship between temperature and resistance, he found that when he cooled
mercury to low temperatures, its resistance suddenly disappeared near 4.2 K, the
evaporating temperature for liquid helium. It was the first discovery of a
superconductor.
254
8 Developing Functional Materials with Marine Organisms
Era, the steam ships of the modern era, and today’s high-speed passenger ships,
boats have been improved in shape and function over time to suit the purposes of
long-term travel. Early boats moved purely by human-generated force; after that
came boats that harnessed the power of the wind. Today, most boats are driven by
motors and propellers. Recently, however, a historic form of boat has been under
development—one with propeller-free, electronic propulsion (Crow et al. 1991).
The electronic propulsion system on this propeller-free boat is based on the
Fleming Left Hand Rule, one of the basic principles of electromagnetics. It became
the subject of much research in the U.S. after first being proposed by Rice in the
1960s, but numerous technological difficulties arise, and no satisfactory results were
achieved. In 1976, the first real development of a propeller-free boat came when a
Kobe University team led by Sachi devised a model that used a superconductor for
an electrical propulsion device. In 1991, Japan’s Shipbuilding Industry Foundation
and Mitsubishi Heavy Industries held a launch ceremony for the world’s first
superconductor-powered electrical ship, the Yamato-1. The ship was just a test
vessel measuring 30 m and 280 tons, with a design speed of 8 knots (around
15 km) and a capacity of 10 people. Once a superconducting coil and superconductor magnetic shielding technology are developed and issues are resolved with
alternative refrigerants for superconducting materials, the future may bring development of a superconducting ship capable of traveling at over 100 knots (about
180 km) without a propeller. (Konishi 1989).
A. What Is Superconductivity?
What is the superconductivity that has made these things possible? Typically, the
term “conductor” is used to refer to materials through which an electric current
travels easily, and “insulator” to those in which it does not. As ordinary metals like
copper increase in temperature, they lose resistance as their atoms experience lattice
vibration. When a current flows, resistance arises as a result of this lattice vibration,
and electricity is lost. (In other words, less than 100% of electricity is received.)
When the metal’s temperature is lowered, its electrical resistance decreases. As it
reaches a certain point close to an absolute temperature of 0 K (−273 °C), some
inherent electrical resistance remains in the metal despite any further cooling. In
some materials, however, electrical resistance suddenly falls to zero at a certain
temperature. This phenomenon is known as superconductivity (Wu et al. 1987).
Superconductivity was first discovered in 1911 by the Dutch physicist Kamerlingh Onnes. In 1908, he succeeded in compressing helium gas to produce liquid
helium at an absolute temperature of 4 K (−269 °C). He then used this to cool
substances to an absolute temperature close to 0 K (−273 °C). As he was studying
the relationship between temperature and resistance, he found that when he cooled
mercury to low temperatures, its resistance suddenly disappeared near 4.2 K, the
evaporating temperature for liquid helium. It was the first discovery of a
superconductor.
254
8 Developing Functional Materials with Marine Organisms