Elimination of electrostatic forces in precision Casimir force measurements using UV and Argon ion radiation

Abstract

Contaminants on the boundary surfaces lead to electric potential inhomogeneities. The resulting poorly defined electric force leads to ambiguities in precision Casimir force measurements. We experimentally demonstrate that with UV light followed by Ar ion beam radiation the electrostatic effects from these patch potentials can be eliminated. The cleaning procedure discussed reduces the sphere-plate potential difference to near zero. In addition, the UV radiation results in vacuum chamber pressures being reduced by a factor of 10 from the removal of volatile molecular species. This leads to very stable and near zero sphere-plate potential differences. The reported combination UV and Ar ion in situ cleaning procedure will find wide application.