What technology does the fast maglev train at 600 km/h use?

Chinese media reported that the country officially launched a maglev train with a maximum speed of up to 600 km / h, one of the fastest land vehicles in the world. The maglev train from Beijing to Shanghai takes only 2.5 hours.

Normal-temperature superconductors will allow electrical energy to be transferred without loss or waste, maglev trains are more efficient, and the use of MRI technology is cheaper and more widespread. more in the future.

What is a superconductor?

A superconductor is a material that achieves superconductivity, a state of matter that has no resistance and does not allow a magnetic field to pass through. The current in a superconductor can last indefinitely.

Superconductivity can usually only be achieved at very cold temperatures. Superconductors have a wide range of everyday applications, from MRI machines to super-fast trains that use magnets to push trains off the tracks to reduce friction. Researchers are now trying to find and develop superconductors that operate at higher temperatures, which will revolutionize energy transport and storage.

Who discovered superconductivity?

Dutch physicist Heike Kamerlingh Onnes is credited with discovering superconductivity. In 1911, Onnes was studying the electrical properties of mercury in his laboratory at Leiden University in the Netherlands when he discovered that the electrical resistance in mercury completely disappeared when he lowered the temperature below 4 ,2 Kelvin - that's just 4.2 degrees Celsius (7.56 degrees Fahrenheit) above absolute zero.

To confirm this result, Onnes applied an electric current to a sample of supercooled mercury, then disconnected the battery. He found that current persisted in mercury without decreasing, confirming the lack of resistance and opening the door to future applications of superconductivity.

Physicists have spent decades trying to understand the nature of superconductivity and what causes it. They found that many elements and materials, but not all, become superconductors when cooled below a certain critical temperature.

In 1933, physicists Walther Meissner and Robert Ochsenfeld discovered that superconductors "expel" any nearby magnetic fields, meaning that weak magnetic fields cannot penetrate deep into the superconductor. This phenomenon is known as the Meissner effect.

It wasn't until 1950 that theoretical physicists Lev Landau and Vitaly Ginzburg published their theories on how superconductors work, according to Ginzburg's biography on the Nobel Prize website. Despite their success in predicting the properties of superconductors, their theory is "macro", meaning it focuses on the large-scale behavior of superconductors while remaining oblivious to the superconductor's behavior. what's going on at the micro level.

Finally, in 1957, physicists John Bardeen, Leon N. Cooper and Robert Schrieffer developed a complete microscopic theory of superconductivity. To create resistance, the electrons in the metal need to bounce freely around. But when the electrons inside the metal become extremely cold, they can pair up, preventing them from bouncing around. These electron pairs, known as Cooper pairs, are very stable at low temperatures, and without any "free" electrons bouncing around, the resistance will disappear.

What are superconductors used for?

Chances are you've encountered a superconductor without realizing it. To generate the strong magnetic fields used in magnetic resonance imaging (MRI) and nuclear magnetic resonance imaging (NMRI), the machines use strong electromagnets, as described by the Mayo Clinic. These powerful electromagnets will melt ordinary metals from even a little bit of resistive heat. However, since a superconductor has no electrical resistance, no heat is generated, and the electromagnet can generate the required magnetic field.

Similar superconducting electromagnets are also used in maglev trains, experimental nuclear fusion reactors, and high-energy particle accelerator laboratories.

The first challenge for researchers today is "to develop superconducting materials at ambient conditions, because currently superconductivity exists only at very low temperatures or at very high pressures". , said Mehmet Dogan, a postdoctoral researcher at the University of California, Berkeley.

Superconductors are divided into two main categories: low-temperature superconductors (LTS), also known as conventional superconductors, and high-temperature superconductors (HTS), or non-conventional superconductors.

Most historical research on superconductivity is in the direction of LTS, because such superconductors are much easier to discover and study, and almost all applications of superconductivity are involved. to LTS.

The secret to superconductor research is finding a material that can act as a superconductor at room temperature. To date, the highest superconducting temperatures have been achieved with extremely high pressure sulfuric carbon hydride, reaching superconductivity at 59 F (15 C, or about 288 K), but requiring 267 gigapascals of pressure to do so. that. That pressure is comparable to the interior of giant planets like Jupiter, which makes it impractical for everyday applications.

Room-temperature superconductors will allow for the transfer of electrical energy without loss or waste, more efficient maglev trains, and cheaper and more widespread use of MRI technology. The practical applications of room-temperature superconductors are limitless - physicists just need to figure out how superconductors behave at room temperature and what the "Goldilocks" materials to enable superconducting might be. .

Developing a maglev train, which is seen as one of China's main goals, aims to upgrade its transportation infrastructure. Specifically, Beijing plans to launch 9 maglev trains that can cover an area of ​​more than 1,000 km .

Responsible agency: Union of Science and High-Tech Production and Telecommunications (HTI) - Vietnam Academy of Science and Technology
Editor in chief: Vo Tran
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