LIMITATIONS OF INSITU CURRENT-DENSITY MAPPING FOR VIBRATING ELECTRODES CLOSE TO METAL-SURFACES

The operation of a vibrating electrode measuring the current densities or field in solution is described based on the use of a lock-in amplifier. The analysis was developed to quantify the effects of a non-uniform field. This was achieved by considering the changes in lock-in amplifier output on increasing the ratio of the vibration amplitude to the distance of the vibrating electrode from a point current source. Significant deviations from the true field occur when the ratio is greater than 0.3 and become 4 times too large at a ratio of about 0.95.