Introduction
Superconducting magnets are solenoids built using special electrical wires producing very powerful magnetic fields. First introduced in 1911, superconducting magnets are now used in a variety of practical applications including cutting-edge research and modern technologies.
History
Superconducting magnets were first theorized in 1911 by Dutch scientist H. Kamerlingh Onnes. Using liquid helium, Onnes cooled a wire made from mercury to nearly absolute zero, or 4 Kelvin. He then studied the wire’s electrical resistance and discovered that it dropped significantly with cooling, eventually becoming zero. This phenomenon was dubbed “superconductivity”. In 1933, his team was able to create a solenoid, or coil of wire, that maintained a steady, powerful magnetic field without the need for an electrical current.
Types
There are two main types of superconducting magnets – persistent and pulsed. Persistent magnets maintain a steady magnetic field for long periods of time, even when the power is turned off. This is accomplished by storing energy in the solenoid’s components. Pulsed magnets generate short, powerful magnetic fields, then dissipate their energy quickly after the power is turned off. While persistent magnets are used in a variety of applications, pulsed magnets are often used in medical imaging or particle accelerator research.
Construction
Superconducting magnets are made from a variety of materials, the most common of which is niobium-titanium (NbTi). The wire is formed into a “flexible bobbin” and wound into a tightly packed coil. Depending on the application, the wire can be as thin as 6 microns in diameter. This thin wire combined with the thick insulation increases the coil’s heat capacity, allowing the magnet to remain cool under heavy use.
Applications
Superconducting magnets are used in a variety of applications, both practically and in research. Their strong magnetic fields are used in magnetic resonance imaging (MRI) scanners, particle accelerators, fusion reactors and magnetic levitation (MagLev) trains. They are also used in superconducting quantum interference device (SQUID) sensors, which measure minute magnetic fields with extreme precision. Research applications are even more varied, with superconducting magnets being used to study superconductors and other materials, magnetization reversal and for testing the properties of high-temperature superconductors in various laboratory experiments.
Conclusion
Superconducting magnets have revolutionized the way industries and research facilities operate. By providing extraordinarily powerful magnetic fields, these magnets have enabled new technologies and scientific endeavors that would not have been possible before. Their ability to generate strong, stable magnetic fields with minimal energy loss has made them an indispensable tool in many fields.
