(27) It Floats: Electrodynamic Ion Trapping

     Earnshaw’s theorem predicts that a charged particle cannot be contained using only static electric and magnetic fields. Electrodynamic (Paul) traps use non-uniform oscillating electric fields to exert a highly... [ view full abstract ]

     Earnshaw’s theorem predicts that a charged particle cannot be contained using only static electric and magnetic fields. Electrodynamic (Paul) traps use non-uniform oscillating electric fields to exert a highly position-dependent force on the trapped particle. Over time, this pushes the particles into the trap, resulting in stable confinement. Such traps provide a platform for several experiments appropriate for advanced undergraduate students, and analyzing the behavior of trapped particles is a powerful tool for teaching the use of Maxwell’s equations. However, design and construction of the trapping apparatus is non-trivial and beyond the scope of a laboratory class. This project provides proof-of-functionality for a custom-built Paul trap, so that the apparatus may be used by future laboratory classes. Experiments in particle characterization are considered, as well as computer simulation of particle dynamics. Analysis of the forces acting on trapped particles is also discussed, especially with regards to the Lorentz force and its uses in particle trapping.