STUDY OF A 5-ELECTRODE QUADRUPOLE LEVITATION-SYSTEM .1. THEORETICAL ASPECTS

A novel quadrupole levitation system with a five electrode structure is designed and constructed to achieve stable levitation of liquid particles in a 1 g environment. The theoretical aspects relating to the design and operation of the system are given, which include derivation of the three-dimensional potential function in a paraxial form and the stability analysis. Based on the three-dimensional potential expression, the stability of the levitated liquid particle is obtained by solving the equations of motion of the charged particles within the quadrupole for the situations with and without the consideration of a viscous damping force. Numerical calculations are made for different electrode geometries to verify the theoretical analysis and to locate the stability domains. Charge-to-mass ratio of levitated particles can be decided either from numerical results or from the analytical expression. The difference in the charge-to-mass ratios obtained from each method is only about 3%.