Investigations Of Capacitive Divider To Measure The Pulse High Voltage Of Electron Beam Acelerator With Water PFL

Intense electron beam accelerators with water PFL (pulse forming line) are widely used in both civilian and military fields such as high-power microwaves (HPM), free electron laser (FEL) and environment safeguard. Currently, repetition is very important development trends for the accelerator. The conventional instrument like resistant divider and the capacitive divider with thin synthetic plastic films over a flat electrode surface are difficult to measure pulse high voltage of such accelerator. The theories of capacitive divider are comparative maturity, the applications of capacitive divider in many laboratories were reported.First, the elements of capacitive divider are analyzed theoretically。The simulations by Pspice show the electric characteristic of capacitive divider. We conclude from the simulation that the capacitive divider can get waveform in the similitude of original waveform when it works in self-integral mode to measure the voltage of hundred nano-seconds.Secondly, a coaxial capacitance divider for the measurement of pulse high voltage of this type accelerator was built. The electric characteristic of capacitive divider is analyzed theoretically, and the parameters of capacitive divider are calculated and measured by experiments. Its time response is about 5ns and division ratio is about 2400, respectively. The divider is employed to measure the pulse high voltage of intense electron beam accelerators with water PFL in our laboratory. The measuring voltage is over 500kV with 80ns during time. The capacitive divider with integrator can be used to monitor the voltage of charging PFL with several microseconds during time, and the voltage is more than 600kV. We compared the results measured by this divider with the resistance dividers. The voltage ratio of capacitive divider is invariable. It shows that this capacitive divider measures the voltage more accurately.Lastly, a capacitive divider for the measurement of pulse high voltage of vacuum diode of accelerators was built. And a vacuum sealing connector for output nano-osecond pulse voltage from vacuum region is studied and constructed. The influences of impedance and length of connector are analyzed in transmission theory. The connector is experimented by 50ns and 10ns rectangle pulse voltage. The experimental results are consistent with theoretical analysis. The distributing capacitance was measured with the calibrating ratio of capacitive divider. We get the division ratio about 4000 and its time response about 4.2 nanosecond by the simulation and experiment.