Magnetic Levitation: How Maglev Works
What if you could travel from New York to Los Angeles in just under seven hours without boarding a plane? This might be possible on a Maglev train.
Maglev – short for magnetic levitation – trains can trace their roots to technology developed at Brookhaven National Laboratory. James Powell and Gordon Danby of Brookhaven received the first patent for a magnetic levitation train design in the late 1960s. The idea came to Powell while sitting in a traffic jam, thinking there must be have a better way to travel on land than traditional cars or trains. He came up with the idea of using superconducting magnets to levitate a train car. Superconducting magnets are electromagnets that are cooled to extreme temperatures during use, greatly increasing the strength of the magnetic field.
The first commercially operated high-speed superconducting Maglev train opened in Shanghai in 2004, while others are in service in Japan and South Korea. In the United States, a number of routes are under consideration to connect cities such as Baltimore and Washington, D.C.
At Maglev, superconducting magnets suspend a train car above a U-shaped concrete guideway. Like regular magnets, these magnets repel each other when their corresponding poles face each other.
“A Maglev train car is just a box with magnets on the four corners,” says Jesse Powell, the Maglev inventor’s son, who now works with his father. It’s a bit more complex than that, but the concept is simple. The magnets used are superconductive, which means that when cooled to less than 450 degrees Fahrenheit below zero, they can generate magnetic fields up to 10 times stronger than ordinary electromagnets, enough to suspend and propel a train.
These magnetic fields interact with simple metal loops inserted into the concrete walls of the Maglev guideway. The loops are made of conductive materials, such as aluminum, and when a magnetic field passes, it creates an electric current which generates another magnetic field.
Three types of loops are placed in the guideway at specific intervals to perform three important tasks: the first creates a field that causes the train to hover about 5 inches above the guideway; a second keeps the train stable horizontally. Both loops use magnetic repulsion to hold the wagon in the optimal location; the further it gets from the center of the guideway or the closer it gets to the bottom, the more the magnetic resistance pushes it back on track.
The third set of loops is an alternating current propulsion system. Here, magnetic attraction and repulsion are used to move the wagon along the guideway. Imagine the box with four magnets – one at each corner. The front corners have magnets with the north poles facing out and the back corners have magnets with the south poles facing out. The electrification of the propulsion loops generates magnetic fields which both pull the train forward from the front and push it forward from the rear.
This floating magnet design creates a smooth trip. Even though the train can travel up to 375 miles per hour, a passenger experiences less turbulence than on traditional steel wheel trains because the only source of friction is the air.
Another big plus is security. Maglev trains are “driven” by the motorized guideway. Two trains traveling the same route cannot catch up and crash because they are all powered to move at the same speed. Likewise, traditional train derailments that occur due to cornering too quickly cannot occur with Maglev. The further a Maglev train moves from its normal position between the walls of the guideway, the stronger the magnetic force pushing it back into place becomes.
This basic functionality is what is most exciting for Jesse Powell. “With Maglev, there is no driver. Vehicles must move where the network sends them. It’s basic physics. So now that we have computer algorithms to route things very efficiently, we could change the entire network schedule on the fly. This leads to a much more flexible transport system in the future,” he said.
While this exciting technology isn’t rolling out in the US today, if Powell and his team are successful, you could one day float to your next destination.