Hyperloop Transportation Technologies, one of two LA-based startups working to build Elon Musk’s futuristic transportation system, announced today that it has licensed a technology called "passive magnetic levitation" to power its prototype. The system is "a cheaper, safer alternative" to regular magnetic levitation, or maglev, which is currently in operation powering high-speed trains in China and Europe.
Passive magnetic levitation, which was developed by the late physicist Richard Post in 2000, uses unpowered loops of wire in the track and permanent magnets in the train pod to create levitation. By contrast, maglev requires complex and expensive infrastructure upgrades, such as power sources placed at intervals along the track. Post, who worked for the Lawrence Livermore National Laboratory in Livermore, California, until his death in 2015, called his new system "the Inductrack."
Called the Inductrack, the new system is passive in that it uses no superconducting magnets or powered electromagnets. Instead it uses permanent room-temperature magnets, similar to the familiar bar magnet, only more powerful. On the underside of each train car is a flat, rectangular array of magnetic bars called a Halbach array. (It is named after its inventor, Klaus Halbach, a retired Lawrence Berkeley National Laboratory physicist.) The bars are arranged in a special pattern, so that the magnetic orientation of each bar is at right angles to the orientations of the adjacent bars [see top illustration on this page]. When the bars are placed in this configuration, the magnetic-field lines combine to produce a very strong field below the array. Above the array, the field lines cancel one another out.
The second critical element is the track, which is embedded with closely packed coils of insulated wire. Each coil is a closed circuit, resembling a rectangular window frame. The Inductrack, as its name suggests, produces levitating force by inducing electric currents in the track. Moving a permanent magnet near a loop of wire will cause a current to flow in the wire, as English physicist Michael Faraday discovered in 1831. When the Inductrack's train cars move forward, the magnets in the Halbach arrays induce currents in the track's coils, which in turn generate an electromagnetic field that repels the arrays. As long as the train is moving above a low critical speed of a few kilometers per hour-a bit faster than walking speed-the Halbach arrays will be levitated a few centimeters above the track's surface.
The Hyperloop, however, is supposed to travel at speeds anything other than "low." According to the design popularized by Musk in 2013, a Hyperloop pod containing either passengers or cargo could travel up to 760 mph through an elevated, airless, and frictionless tube between cities. Theoretically, travel between San Francisco and LA could take 30 minutes.
"Utilizing a passive levitation system will eliminate the need for power stations along the Hyperloop track, which makes this system the most suitable for the application and will keep construction costs low," said Bibop Gresta, chief operating officer of Hyperloop Transportation Technologies, in a statement. "From a safety aspect, the system has huge advantages, levitation occurs purely through movement, therefore if any type of power failure occurs, Hyperloop pods would continue to levitate and only after reaching minimal speeds touch the ground."
Two companies — Hyperloop Transportation Technologies (HTT) and the (similarly named) Hyperloop Technologies Inc. (HTI) — are locked in a fierce competition to be the first to demonstrate the feasibility of Musk's vision. Notably, HTT made its announcement almost 48 hours before HTI planned to hold a demonstration of its technology for reporters in North Las Vegas. Musk's company SpaceX is also building a Hyperloop track on which it will test pods created by winners of its design competition at Texas A&M University last January.
Unlike HTI, which is a traditional tech startup with investors and a board that includes former Obama strategist Jim Messina, HTT boasts that it is a solely volunteer and crowdsourced venture. The company says it has talent from NASA, Boeing, Tesla, and SpaceX working among its 480-plus volunteers.
Asked about the timing of its announcement, Hyperloop Transportation CEO Dirk Ahlborn said in an email he was "not sure about [Hyperloop Technologies, but] as for us, my travel schedule and other announcements that are coming over the next couple of weeks determine when we do our releases."
Ahlborn added, "Personally I think any progress in the technology is positive for us. We started the movement back in 2013 when everybody said it's not possible, today it's not a question anymore [of] if, just when."
Ahlborn's company recently filed permits in Kings County, California to build a 5-mile test track around Quay Valley, a proposed 75,000-resident solar-powered community halfway between San Francisco and Los Angeles. And in March, HTT announced it had reached a deal with the government of Slovakia to explore building a system in the central European country.