What is "ampere-turn"

ampere-turn \ampere-turn\, Ampere turn \Amp[`e]re turn\ (Elec.) A unit of magnetomotive force equal to the product of one complete convolution (of a coiled conductor) into one amp[`e]re of current; thus, a conductor having five convolutions and carrying a current of half an amp[`e]re is said to have 21/2 amp[`e]re turns. The magnetizing effect of a coil is proportional to the number of its amp[`e]re turns.

n. the unit of magnetomotive force

n. a unit of magnetomotive force equal to the magnetomotive force produced by the passage of 1 ampere through 1 complete turn of a coil; equal to 1.257 gilberts

The ampere-turn (AT) is the MKS (Meters, Kilograms, Seconds) unit of magnetomotive force (MMF), represented by a direct current of one ampere flowing in a single-turn loop in a vacuum. " Turns" refers to the winding number of an electrical conductor comprising an inductor.

For example, a current of 2A flowing through a coil of 10 turns produces an MMF of 20 AT.

By maintaining the same current and increasing the number of loops or turns of the coil, the strength of the magnetic field increases because each loop or turn of the coil sets up its own magnetic field. The magnetic field unites with the fields of the other loops to produce the field around the entire coil making the total magnetic field stronger.

The strength of the magnetic field is not linearly related to the ampere turns when a magnetic material is used as a part of the system. Also, the material within the magnet carrying the magnetic flux "saturates" at some point, when adding more ampere turns has little effect.

The ampere-turn is equal to 4π/10 gilberts, the equivalent CGS unit.

Alternatively, NI has been used in industry, specifically, US based coil making industries.