Abstract: The invention relates to a high voltage electromagnetic pulse generator.This generator comprises a capacitor having an axis of revolution, disposed about an internal conductor and charged by means of a high voltage direct current power supply, a conical spark gap, whose axis of revolution coincides with that of the capacitor, having first and second electrodes and used for discharging the capacitor, a ballast resistor having an axis of revolution, connected in series with the spark gap in such a way that the first electrode is connected to the high voltage terminal of the power supply and the second electrode to the earth of said power supply via the ballast resistor and the internal conductor and electromagnetic control means for the spark gap, the capacitor, spark gap and ballest resistor forming with the internal conductor a coaxial line having a constant impedance along the line.