A simple and reliable capacitive-RC hybrid probe, designed for voltage measurement of fast pulse discharge systems, is presented. Further, besides its power handling capacity, it can be easily adapted to suit other pulse discharge systems.
S. Lee · 2002
(Received 17 September 1990; accepted for publication 10 October 1990) A simple and reliable capacitive-RC hybrid probe, designed for voltage measurement of fast pulse discharge systems, is presented. Further, besides its power handling capacity, it can be easily adapted to suit other pulse discharge systems. Various types of voltage probes have been designed to measure voltage signals of pulse (discharge systems in place of the conventional resistive divider probe. This is because as the magnitude and the rise time of the voltage signal increases, a resistive divider becomes limited by its power handling capacity and the introduction of its self induc- tance, which affects the response of the probe. In such cases, a capacitive divider probeie3 with its high-frequency characteristic, linearity, and its small loading of the high- voltage circuit has been found to be superior. It has also been successfully utilized in the measurement of high- voltage transients in liquid filled transmission lines with response up to 10 ns and 10 MV.4*5 A capacitive voltage probe system is presented here to measure the voltage sig- nal of the UMCSZP,6 a Z-pin& system. It consists of a capacitive divider stage at the voltage source and a RC section at the measuring end. It lhas been used successfully to measure the voltage signal of I:he pinch compression. In situ calibration is possible by firing the pinch system at a lower pressure, whereby the voltage switch-over is momen- tarily held across the anode and the cathode before the gas breakdown. An added advantage is that even if the voltage switched over is held for a long time before pinching occurs there is no destruction of the p,robe due to excess power dissipation. A schematic diagram of the capacitive voltage system is shown in Fig. 1. It consists of a capacitive divider stage at the voltage source and an optional RC stage at the mea- suring end. Capacitor C, is a coaxial capacitor consisting of an insulated copper wire capacitively coupled to the anode flange of the Z-pinch machine. It sits on the cathode flange and is housed in a copper tube with a BNC connector for connection to C,. The design of C, is shown in Fig. 2. Capacitor C, is the coaxial cable used to carry the signal to the measuring end. The output voltage measured is pro- portional to the input voltage and is given by