Superconducting magnet

Construction

Composition

Coil windings

The coil windings of superconducting magnet are made of wires of a type 2 superconductor(e.g.niobium-titanium).

Coil

The coil itself is made of tiny filaments( about 20 micrometers thick)of a type 2 superconductor, coated with copper. The copper coating is needed for adding mechanical strength to the fiber and in case the termperature rises above T_c or I_c when superconductivity is lost. These filaments need to be this small because in this type of superconductor, the current only flows skindeep.

Cooling

liquid helium is used as cool-liquid since this is the only material wich is liquid at the extreme temperatures of superconductors.

Materials

rtunately it is far more difficult in making the requiered filaments. This isMostly the superconducting part is made in titanium-niobium. This material has critical temperature of 10 kelvin and remains in this state till about 15 tesla. More expensive magnets can be made of niobium-tin (Ni₃Sn). These have a T_c of 18 kelvin. When operating at 10 kelvin they are able for withstanding a much higher magnetic field intensity. Unfortunately it is far more difficult in making the requiered filaments.This is why sometimes a combination of Ni₃Sn in the high energy parts and Ni₃Ti for the lower energy part is used.

Use

Superconducting magnets can reach a much magnetic field intensity than normal magnetsand they can hold this field for a long time. This is particullary needed in Particle accelerators and Nuclear magnetic resonance. For economical reasons it is also adviced using this type of magnets when more than 1 tesla is needed for a long time.