*Article* **Research on Characteristics of Copper Foil Three-Electrode Planar Spark Gap High Voltage Switch Integrated with EFI**

**Kehua Han 1,2, Wanjun Zhao 1,\*, Peng Deng 1, Enyi Chu <sup>2</sup> and Qingjie Jiao <sup>1</sup>**


**\*** Correspondence: wanjunzhaowj@bit.edu.cn

**Abstract:** In view of the low-energy explosion foil detonation system's requirements for the integration technology of high-voltage switches and technical overload resistance technology, a magnetron sputtering coater is used to sputter copper film on the surface of the substrate. The thickness is 4.0 μm, the radius of the main electrode is 4 mm, the trigger electrode is 0.6 mm and 0.8 mm, and the main gaps are 0.8 mm, 1.0 mm, 1.2 mm mm, 1.8 mm, 2.0 mm, 2.2 mm, and 2.6 mm. Copper foil three-electrode planar spark gap high voltage switches are designed and manufactured; and the static self-breakdown characteristics, dynamic operating characteristics, and discharge life characteristics of the three-electrode planar spark gap high voltage switch based on copper foil are studied in this paper. The test results show that with the increase of the main electrode gap from 0.8 mm to 2.6 mm, the self-breakdown voltage of the planar spark gap switch increases, and the working voltage also increases. When the main electrode gap is a maximum of 2.6 mm, the self-breakdown voltage of the switch can reach 3480 V, which indicates that the maximum operating voltage of the switch is 3480 V. When the charging voltage is 2.0 kV, with the increase of the main electrode gap from 0.8 mm to 2.6 mm, the minimum trigger voltage value of the planar spark gap switch increases from 677 V to 1783 V (*a* = 0.6 mm), and from 685 V to 1766 V (*a* = 0.8 mm), the switch on time is 16 ns, 22 ns, 28 ns, 48 ns, 64 ns, 77 ns, 93 ns (*a* = 0.6 mm), and 26 ns, 34 ns, 51 ns, 67 ns, 81 ns, 102 ns (*a* = 0.6 mm). With the increase of the gap between the two main electrodes of the switch, the maximum static working voltage of the three-electrode plane spark gap high-voltage switch increases, the minimum trigger voltage value also increases, and the on-time of the switch gradually becomes longer. The peak current of the discharge circuit decreases and the dynamic impedance and inductive reactance of the switch also increase; as the width of the trigger electrode increases, the minimum trigger voltage decreases, the dynamic impedance and inductance decrease, and the switch operating voltage with the same parameters is higher. The easier the switch is to turn on, the lower the minimum trigger voltage. The electrode thickness of the three-electrode plane spark gap switch has a certain influence on the field strength and the service life of the switch. The results of this study provide useful references for promoting the research and development of LEEFIs.

**Keywords:** three-electrode planar spark gap high voltage switch; static characteristics; dynamic characteristics; impedance characteristics; electric field strength
