Effect of Electrode Material to Current-Voltage Characteristics of a Gerdien Condenser

Effects due to kind of materials used for the collector electrode of a Gerdien condenser upon the current-voltage (I-V) characteristics were investigated. Aluminum, copper and nickel electrodes were initially polished and cleaned and the I-V characteristics were recorded with 15-minutes interval under exposure to ambient air. Results showed that the zero-crossing voltage in the I-V curve shifted toward negative electrical potential, while the saturation current decreased in accordance with the passage of time. The electrode surfaces showed clear change in the color after operation. Ion mobilities and ion species concentrations were determined from the measured I-V characteristics and they indicate sizable difference by the electrode aging effect. The aluminum electrode showed stable positive and negative saturation currents within 180 minutes, while the saturation current decreased down to 50% of the initial value. (C) 2016 The Japan Society of Plasma Science and Nuclear Fusion Research