Measurement of Transient Electric Fields in Air Gap Discharge With an Integrated Electro-Optic Sensor

The spatial electric field is a key parameter for gas discharge research. Based on the electro-optic effect, a small size (mm), wide measuring-amplitude (MV/m), mono-shield structure, integrated electro-optic sensor is designed and developed. The ns-level time domain calibration system of the sensor is established. The calibration result shows that the output electric field is linear with the input signal, and the dynamic response time of the sensor is less than 2 ns. Using the developed sensors, the spatial electric field of a 1-m rod-plane air gap discharge is tested and the sudden step of an electric field is detected. As the imposed voltage increases, the probability and amplitude of the electric field step increased as well. This step phenomenon is confirmed to be the inception and development of a streamer; the confirmation is made by means of simultaneously captured photos. The rise time and the amplitude of the electric field step are discussed. Accordingly, the integrated electro-optic sensor will be a powerful tool for studying the mechanism of air gap discharges.