An ion trap confines charged particles (typically ions) in a region of space using electric and/or magnetic fields. Typical examples include the Penning Trap, Paul Trap, and electrostatic traps (e.g. Kingdon/orbitrap).
Ion motion in an ion trap, at least for an ideal quadrupole trap, can be described by the Mathieu Equation and Stability Diagram.
SIMION has frequently been used to simulate various types of ion traps.
- Earnshaw’s Theorem
- Time-Dependent Field
-  March, Raymond E. “An Introduction to Quadrupole Ion Trap Mass Spectrometry” Journal of Mass Spectrometry, volume 32, issue 4, year 1997, pp. 351-369, doi:10.1002/(SICI)1096-9888(199704)32:4<351::AID-JMS512>3.0.CO;2-Y link (spectroscopynow.com)
-  Wong, Philip S.H. Cooks, R. Graham. “Ion Trap Mass Spectrometry”. currentseparations. http://www.currentseparations.com/issues/16-3/cs16-3c.pdf