What is a Superconducting Magnet?
A superconducting magnet is an electromagnet where the coils are made of a type II superconductor. It can easily create steady magnetic fields of 100,000 Oersted (8,000,000 amperes per meter). They produce stronger magnetic fields than standard iron-core electromagnets and cost less to operate. In order to understand what a superconducting magnet is, it is important to know a bit about superconductivity. When certain metals and ceramics are cooled from a range of degrees near absolute zero, they lose their electrical resistance. This temperature is called critical temperature (Tc) and is different for each material. When there is no electrical resistance, electrons can roam freely throughout the material. The element can hold large amounts of current for long periods of time without losing energy as heat. This ability to hold an extreme electrical charge is called superconductivity. Most metals have a woven sort of atomic structure. Their electrons are loosely held, so that they can mo
How is it different from ordinary magnets? A. The main difference between superconducting magnets and conventional room temperature electromagnets, is that they use low temperature, zero electrical resistance conductor wire in the magnet winding, instead of room temperature, non-zero electrical resistance conductor. Conventional electromagnets use aluminum or copper conductor, while superconductor magnets use niobium-titanium-copper wire (or other superconductor, depending on application). Also, conventional electromagnets often use iron cores to reduce the current and I2R losses in the conductor winding. Because superconductors have no electrical resistance, very high currents and current densities are practical, resulting in much more powerful electromagnets than are possible with room temperature conductors. While room temperature permanent magnets have no current windings or I2R losses, their inherent physical characteristics limit their magnetic field capabilities to much less tha
Electric currents are magnetic. That’s the basis for electromagnets—if you run an electric current around a coil of wire, that coil of wire will develop a north magnetic pole at one end and a south magnetic pole at the other end. But an electromagnet made with normal copper wires consumes electric power all the time. The current passing through those wires wastes energy because of friction-like effects in the copper and the wires become hot. The electromagnet also needs a power source to keep its current flowing. However, a superconducting electromagnet is one in which the wires are superconducting—the current passing through them doesn’t waste any power. Once a current has been started in a coil of superconducting wire, it flows forever. Since it doesn’t waste any power, that current needs no source of power and produces no thermal energy. In fact, you can buy superconducting magnets with the current already started at the factory. As long as the wires are kept cold (as they must be t
