A multiple-approximation method to calibrate switch capacitive voltage dividers without standard probe in Tesla-type generators

When a capacitive voltage divider (CVD) in a component is calibrated, the introduction of a standard high-voltage (HV) probe usually affects the original field distribution of this component. Therefore, the voltage ratio of the CVD is affected, especially when the distance between the HV probe and the CVD is close. A multiple-approximation method to calibrate the CVD of gas switches in Tesla-type generator without a standard HV probe is being put forward. The basic idea is to calculate the theoretical switch voltage uth based on the equivalent circuit of this type of generators and to use uth to substitute the real voltage ur acquired by the standard HV probe to calculate the voltage ratio β for the CVD of a gas switch. Since the gas-gap resistance Rs of the switch is not zero, uth is not equal to ur, and β therefore deviates from the real value β0. To solve this question, two steps are implemented: first, β(d) at different gas-gap distances d is obtained; second, the true voltage ratio β(0) when d = 0 is extrapolated. The theoretical basis of this method was analyzed first. Then, it is verified by experiments. In the end, the uncertainty of this method is evaluated.