Use of Capacitive Detection to Measure Harmonic Generation and the Nonlinearity Parameter in Liquids
William T. Yost · AIP conference proceedings · 2005
Capacitive detectors have been employed for some time for absolute measurement of compressional wave particle displacement amplitudes in solids. The solid’s surface has been used as one of the capacitor’s plates, and a conductor riding within a few microns above the surface as the other plate. In the arrangement discussed here a conductive membrane is placed in contact with the liquid and the other electrode is placed a few microns above the membrane. Using this device the particle displacement amplitude in the picometer range of fundamental and harmonic waves in water were successfully measured. Measurements of fundamental and harmonic waves are presented and analyzed. Membrane effects and corrections related to liquid measurements are presented. The nonlinearity parameter for water is calculated, presented, and discussed.