Maglev: the history
However, if the train strays away from the centre, a difference in EMF is formed between the left and right coils, resulting in a net current flow. A net horizontal component of the force will then be formed from the coils, forcing the train back to the centre, where the force disappears (see figure 12). The superconductor within the train only needs to be charged once to produce a circulating DC current with no energy loss of around 700 kA, nearly 10 thousand times the current in conventional household wires. Liquid helium is used to cool the
Figure 12: Force analysis when the superconductor strays from the centre (Lesics, YouTube)
superconductor below its critical temperature of 9.2 Kelvin, along with a radiation shield that prevents it from absorbing outside heat. A vacuum is required inside the entire radiation shield to prevent heating via convection, while liquid nitrogen is also used to cool the interior. Four superconductors are arranged as units, with multiple of these units arranged throughout the body of the train.
Significance
Up until this point, there are still a lot of unanswered questions: what is the significance of all this? Does the performance of these prototypes justify the vast amount of funds poured into these projects? The short answer on the surface is unsurprisingly ‘ no ’ , but as our technology improves and new construction methods are employed, construction costs are expected to drop. 16
Comparison with other similar conventional transport (High-speed trains and airplanes)
Speed and acceleration: Maglevs can achieve higher top speeds than conventional rail while also accelerating and decelerating faster due to their frictionless nature. Compared to conventional airlines, maglevs do not require complicated procedures for take-off and landing or extended security checks. This significantly reduces travel time.
Noise: Due to their contactless nature, Maglevs do not produce nearly as much noise as a wheeled train at the same speed, as there is no contact or friction between the train and the track.
Efficiency and maintenance: While a wheeled train is arguably more efficient at lower speeds, maglevs don’t experience rolling resistance due to the absence of wheels, so efficiency is improved at higher speeds, which includes most of the time due to the maglev’s rapid acceleration. Maglev systems are also demonstrated to require minimal overall maintenance, while a conventional mechanical system will periodically require regular maintenance due to the wear and tear on its components caused by friction. Conventional railway tracks are also subjected to this, while maglev rails aren’t. However, as the scenarios are very different, maglev rails need to be designed and optimised individually.
16 ‘Cost data – HSM vs. Existing Modes’, North American Maglev Transport Institute (Jan 2011), https://web.archive.org/web/20110919090834/http://namti.org/?page_id=275; consulted: 30/7/2023.
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