Air gap*

An air gap is a non-magnetic region intentionally introduced into the magnetic flux path in order to control magnetic flux distribution, inductance, energy storage capability, and force generation in electromagnetic devices.

Air gaps are used in transformers, inductors, electric machines, magnetic actuators, relays, and electromagnetic sensors. Gap length strongly affects magnetic reluctance, flux level, force, and inductance, and it also reduces sensitivity to nonlinear magnetic material properties such as saturation.

Air gap analysis is commonly required when evaluating magnetic force, stored magnetic energy, and inductance stability. In QuickField, such problems are usually analysed using DC Magnetics or AC Magnetics packages depending on excitation conditions.

References
Wikipedia: Air gap (magnetic)
E-Magnetica: Air gap

QuickField examples
Equivalent airgap (Carter coefficient),
Magnetic core air gap energy,
Magnetic field simulation in DC motor air gap

^*We do not guarantee that articles in the section "Glossary" are full and exact or that they may be used as a reference of any kind. In fact - they are not! These are just informal hints, letting the students and amateurs better understand what the specific term is about. Experts should not read it at all! However, we will appreciate all expert recommendations about improving and extending our glossary.