**3. Research on the Characteristics of High-Voltage Switching with Three-Electrode Plane Spark Gap**

#### *3.1. Test Device and Principle*

For the performance test of the three-electrode planar spark gap high-voltage switch, the test device includes a high-voltage power supplied with the output voltage of 0~4 kV and accuracy of 1‰, a pulse trigger power supplied with the adjustable output voltage of 0~3 kV, a rising pulse time of no more than 100 ns and falling pulse time of no more than 1 μs, a digital high-voltage meter with input impedance of 1000 mΩ and measurement accuracy of 1‰, the Rogofiski Roche current measuring coil with the model specification of 5008c, a voltage divider of 1/1000, and a high voltage pulse capacitor with the model specification of C471/0.2 μF/3.0 kV. The test principle is shown in Figure 5.

**Figure 5.** Schematic diagram of test principle.

As shown in Figure 5, the high-voltage DC power supply outputs the working voltage *USB* to the positive electrode of the high-voltage capacitor and the three-electrode plane spark gap high-voltage switch, and the pulse trigger power supply provides the trigger voltage *Utrigger* to the three-electrode plane spark-gap high-voltage switch. When the electric field strength between the trigger electrode and the main electrode is greater than the breakdown strength of the air in the gap, a breakdown occurs between the gaps, the electric field in the gap is distorted, and a large number of electrons in the negative electrode of the main electrode rapidly move to the positive electrode to turn on the switch. The high-voltage capacitor discharges the load through the three-electrode plane spark gap high-voltage switch, and uses the Rogowski coil, the high-voltage probe and the voltage divider, and the oscilloscope to test the discharge current, working voltage, and trigger voltage in the loop, respectively.
