THE NONLINEAR ION-TRAP .3. MULTIPOLE COMPONENTS IN 3 TYPES OF PRACTICAL ION-TRAP

A general analytical method is introduced to study quantitatively the multipole components of potential fields in three types of practical i on trap with finite electrode size: (a) the truncated Paul ion trap; ( b) the truncated ion trap with modified hyperbolic angle; (c) the trun cated ion trap with stretched end-cap distance. Surface charge densiti es on ring and cap electrodes and capacitances of ion traps are calcul ated. The analysis point out different properties of the three electro de structures, and presents a potential distribution which allows the study of ion motion in these practical ion traps.