DIRECT DETERMINATION OF 3D FORCES APPLIED ON A PARTICLE SUSPENDED IN AN ELECTRODYNAMIC CHAMBER

The main motivation of the present work is to enable one to carry out a direct quantitative measurement of 3D force balance applied on a sus pended particle in an electrodynamic chamber (EDC). For this, the abso lute values of electric field parameters are essential. Both horizonta l and vertical electric field components were analysed theoretically a nd experimentally. From the theoretical analysis of the motion of a ch arged particle in an EDC, two relationships relating motion parameters to electric field strength were found. These relationships were valid ated experimentally from measurements of 17 polystyrene and char parti cles with various densities and sizes. Consequently, the absolute 3D f ield parameters were determined. This method was used to determine the absolute value of the photophoretic force (PPF) and the free convecti on force (FCF) applied on a suspended particle. In these experiments, the particle was irradiated horizontally by a focused laser beam. Cons equently, the PPF was developed horizontally whereas the FCF was devel oped vertically. The present measurement indicated that the PPF is muc h smaller than the FCF, in contrast to previous reports.