Trapping two-particle arrays in a double-ring electrodynamic balance

A new technique has been developed to explore the characteristics and dynamics of the electrodynamic balance (EDB). IL is demonstrated that by trapping a pair of microparticles, the electric field of and EDB can be characterized and particle stability can be investigated, The electric field in the neighborhood of the null-point was examined by comparing the oscillatory motion of the two-particle system with a theoretical analysis. In addition, the relevant balance constants were evaluated by five methods: (i) determination of the stabilization strength constant, C-1, using measurements on two-particle arrays, (ii) determination of the levitation strength constant, Co, using measurements on single particles of known mass and charge, (iii) computation of C, and C, by solving the three-dimensional Laplace equation for the non axisymmetric electrode system, (iv) computation of Co using a ring charge simulation technique, and (v) determination of the ratio C-1/C-0 by measurements of the marginal stability limit. The results of the different methods are compared and shown to be consistent. (C) 1997 Elsevier Science Ltd. All rights reserved.