 An Introduction to Magnetic Levitation And it’s Applications



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An Introduction to Magnetic Levitation

And it’s Applications


Kevin J. Van Dyke, Student Member, IEEE


Abstract—Magnetic Levitation is a technology that has been experimented with intensely over the past couple decades. It wasn’t until the last ten years when scientists began to develop systems that would use magnetic levitation as a means of transport. This paper outlines the methods behind magnetic levitation, as well as the technologies implemented using the levitation. The implementation of a large-scale transportation system using magnetic levitation has huge social as well as economical effects. These aspects are looked at in a number of situations to see if the effort in producing a system using magnets is worth the time and effort in researching.

  1. INTRODUCTION


Some forces in this world are almost invisible to the naked eye and most people throughout the world do not even know they exist. On one side you could say that some of these forces are abstract feelings inside of a human being that have been given names from man. These forces could be things like emotion, guilt, and even ecstasy. On the other side you have solid concrete principles of how the world works. These too have been given names by man, but these principles are not abstract and have solid ground in science. These different principles are things like gravity, electricity, and magnetism. Magnetism has been a part of the earth since the beginning whether people realize it or not. It is due to the magnetism of the earth that the world spins and thus creates things like gravity. The magnetism is created by the processes within the core of the earth. The earth’s iron-ore core has a natural spinning motion to it inside which creates a natural magnetic force that is held constant over the earth. This creates magnetic forces that turn the earth into a large bar magnet. The creation of North and South poles on the earth are due to this field.

From this magnetic field, we see things such as the aurora borealis. This is a small electromagnetic storm in the atmosphere which creates a display for all to see. Not only does magnetism provide us with amazing natural displays, but it also provides for us amazing applications to society. One of these applications is magnetic levitation. Magnetic levitation uses the concept of a magnets natural repulsion to poles of the same kind. This repulsion has been harnessed and controlled in an environment to help create a system of transportation that is both economically sound and faster then most methods of transportation at this point.

In 1965 the Department of Commerce established the High Speed Ground Transportation Act. Most early work on developing Maglev technology was developed during this time. The earliest work was carried out by the Brookhaven National Laboratory, Massachusetts Institute of Technology, Ford, Stanford Research Institute, Rohr Industries, Boeing Aerospace Co., and the Garrett Corporation. In the United States, though, the work ended in 1975 with the termination of Federal Funding for high-speed ground transportation and research. It was at that time when the Japanese and German developers continued their research and therefore came out with the first test tracks.

In 1990, legislative action directed the U.S. Army Corps of Engineers to implement and prepare a plan for a National Maglev program. The Department of Transportation (DOT), Department of Energy (DOE), and the Army Corp developed what is know as the National Maglev Initiative which was a two year 25 million dollar program to assess the engineering, economic, environmental and safety aspects of Maglev.


  1. Basics of Magnetic levitation

    1. Magnetic Fields


The creation of magnetic forces is the basis of all magnetic levitation. The creation of a magnetic field can be caused by a number of things. The first thing that it can be caused by is a permanent magnet. These magnets are a solid material in which there is an induced North and South pole. These will be described further a little later. The second way that an magnetic field can be created is through an electric field changing linearly with time. The third and final way to create a magnetic field is through the use of direct current.

There are two basic principles in dealing with the concept of magnetic levitation. The first law that is applied was created by Michael Faraday. This is commonly known as Faraday’s Law.


Figure 1. Michael Faraday


This law states that if there is a change in the magnetic field on a coil of wire, there is seen a change in voltage. Taking that a bit further, it could be said that if there was a change in voltage, then there would be a change in magnetic field. This occurs in the coil when there is a current induced as a result of that change in voltage. From Figure 2 below it is illustrated that the change in the magnetic field produces a current.

Figure 2. Induced Current from Change in Magnetic Field


For the purposes of magnetic levitation the ability to change the strength of a magnetic field by just changing the current is powerful. If there is a need for more of a force, then sending more current through a coil of wires will produce more of a greater magnetic force.

The direction of the forces created by Faraday’s Law was discovered by a man named Heinrich Lenz. His theory states that “the emf induced in an electric circuit always acts in such a direction that the current it drives around the circuit opposes the change in the magnetic flux which produces the emf.”1 In other words, this is stating that if there was a current that was created in a coil of wires, then the magnetic field that is being produced will be perpendicular the current direction.


Figure 3. Heinrich Lenz


The application that this has on magnetic levitation is that this will allow the direction of the magnetic field to be predictable and thus a set up can be created for a specific purpose to maximize the force that is created. This has direct application to the rail gun which will be described later.

Figure 4. Perpendicular Force from Induce Current


From Figure 4 above, it is illustrated that there is a coiled wire around the cylinder. Inside that coiled wire is a current that is traveling from left to right. The resulting magnetic force from that current is shown to be perpendicular to the current and is traveling from bottom to top.



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