Probing the wetted perimeter in a He II two-phase pipe-flow experiment using a capacitive sensor

摘要

We report on the performances of a capacitive sensor designed to probe the wetting by a liquid film in a pipe-flow experiment. Two 0.2μm thick inter-digitised gold electrodes deposited on a single thin kapton foil constitute a soft capacitor that can conveniently fit onto the pipe walls without disturbing the flow. Selectivity on the minimum thickness of the film to be observed is achieved by properly choosing the distance between the two electrodes, and we discuss the case of a 100 μm gap capacitor. Some results in the specific situation of a cryogenic two-phase helium flow experiment for which a typical resolution of 0.2% in wetted perimeter is obtained are discussed.