Operating Parameters of a Quadrupole in a Grounded Cylindrical Housing

摘要: Quadrupole theory and design are based on the solution of Mathieu’s equations, which assume that zero potential, except for symmetry axes between electrodes, is infinitely far away. In practice, quadrupole rods mounted within a grounded housing not much larger than electrode structure itself. This study determines operating parameters optimum size with electrodes circular cross section located zero-potential cylindrical surface. It found rod only weakly dependent location external, surface r=1.1468r0 cylinder radius 3.54r0. Although 1.15% smaller commonly used value r=1.16r0, it 43% higher sensitivity at resolution 400 (ΔM measured half-height) results from using electrodes.