Time-domain reflectometry of high-voltage nonlinear loads with picosecond resolution

The construction and characterization of a measuring module for high voltage time-domain reflectometry with picosecond resolution is presented. The device provides registration of low-distortion reflections from the load at conditions of irregular shape and pronounced instability of an incident probing pulse with amplitude of hundreds of kilovolts and a width/front up to ~2 ns. This is achieved with registration of differential reflecting signals by using two voltage probes, whose original signals are shifted in time and have a calibrated delay. Specially designed voltage dividers based on coaxial coupled lines with equalized dielectric constant of insulation meet the requirements of voltage probes identity. Reflectometry allows one to study dynamic changes of the loads for a specific time range of ~10(-10) s and faster. An example of reflectometry-based analysis for variations in breakdown development rate of atmospheric discharge gap supplied with the pulses of ~100-kV amplitude and a front slope of ~4 × 10(14) V/s is presented.