Study On One-dimension Pulse Current Injection Technology

The interference of pulse current will occur on the one dimension structural electronic components such as data transmission line, command control line, power supply line, and cable etc, which exist in the high-altitude nuclear electromagnetic pulse (HEMP) environment, and that could damage the electronic equipment linked with these lines. The pulsed current injection (PCI) is one of simple and reliable method for the electromagnetic susceptivity test of electronic equipment. In this paper, the pulse current injection technology and related electromagnetic susceptivity test method on electronic components were studied by theory analysis and experiments.The current responses on line in HEMP environment were analyzed using the transmission line theory. The current responses on lines laying near ground were calculated according to the following different situations: two terminals in short-circuit state, two terminals connected with high resistances, one terminal in short-circuit state and one terminal linked with resistance, two terminals connected with different resistances respectively. The calculated results were taken as the fundaments of pulse current inject equipment design.A set of pulse current inject equipment was researched and developed. This equipment works in non-contact mode. The main component parts include capacitance, which was used as energy storage, gas spark discharge switch, magnetic field coupling component etc. 150-A pulse current can be injected into transmission line with the length of 4 meters, and the output current amplitude can be adjusted.The experiment method of PCI for line and electronic circuit with certain function and the test method of electromagnetic susceptivity are developed. The experiment system for communication line of computer, which can detect the state of communication, is developed. The inject current is detected by developed caliper-mode pulse current detector.The electromagnetic susceptivity upset threshold value and damage threshold value are defined. RS-232 and RS-422 communication interface circuits are selected for EMP upset threshold and damage threshold test. The threshold values of these two kind circuits are obtained, the primary analyses are given at last. The results indicate that the damage mode is current damage, too high inject current makes the interface circuit breakdown inside, whereas the voltage on the port just changes the input resistance characteristic of the port. The upset threshold and damage threshold are described in the form of energy. There is high possibility to make RS-232 and RS-422 breakdown when the inject current is higher than 10 A, inject energy is above 10-3 J.The induced current on line is researched theoretically and experimentally according to two situations: one terminal in short-circuit state and one terminal linked with resistance, two terminals connected with different resistances respectively. The results indicate that the induced current on line and the voltage on the end resistance had nonlinear relationships. The dissipative energy by the resistance would reach the maximum value when special resistance values are selected. The experiment results are identical to those one obtained from theory calculation.