Regarding Superconducting Linear Cooling
Maglev trains are driven using superconducting magnets. By utilizing the superconducting phenomenon where electrical resistance becomes zero at a low temperature of 4K (-269 degrees Celsius), a strong magnetic field can be generated without any loss of electrical energy.
To maintain the superconducting state continuously, a cooling structure must be installed. Previously, liquid helium was used for cooling. However, liquid helium is expensive, and the equipment needed to ensure safety has the drawback of being large in size.
In recent years, by changing the material of the coils that make up superconducting magnets, direct cooling without liquid helium has become possible. The material used is bismuth-based copper oxide, which can maintain a superconducting state at a higher temperature than before. Cooling to 20K (-253 degrees Celsius) is achievable, and such magnets are called high-temperature superconducting magnets.
The devices used to cool high-temperature superconducting magnets employ a method of directly cooling the material through adiabatic expansion. Thanks to technological improvements in the coolers themselves, efforts to make them lighter and more compact have been advancing.
As the practical application of high-temperature superconducting magnets, including their cooling devices, further progresses, they will make significant contributions to energy conservation, cost reduction, and improved stability.
