Kerr Cell Measuring System for High Voltage Pulses

Abstract

This paper describes a system to measure, with very high resolution, high voltage pulses. The system is based on a unique application of the electro-optic Kerr effect and measures voltage pulses with magnitudes from 3×104 to 1×105 V. This technique also could be used to measure higher voltages by changing the separation of the Kerr cell plates. The system has a linear frequency response to approximately 100 MHz. Unlike the resolution of other voltage-measuring systems, the resolution of this system increases as the voltage pulse increases towards its peak value. The peak pulse magnitude can be measured with a resolution of better than 0.1%. The system can be calibrated so that the measured value of the peak voltage should be accurate to within ±1% of the true value. This high resolution is obtained by modulation of a constant intensity light source by action of a Kerr cell. The electric field intensity resulting from the high voltage pulse causes phase differences as great as 25π radians between light components in the Kerr cell. Consequently, many light cycles are obtained during the voltage rise of the pulse. This produces extreme resolution near the peak of the pulse. Near the peak, a 2% change in voltage results in a 100% change in light intensity.