Abstract: During AC-side fault ride-through of the Baihetan-Jiangsu ±800 kV hybrid DC transmission project, a controlled self-recovery dissipation device was added in order to limit the overvoltage absorption of redundant energy on the flexible bus. In order to achieve a rapid 1ms input of the controlled self-recovery dissipation device, a DC 80 kV SF₆/N₂ plasma jet trigger gap needs to be developed. According to the engineering requirements, the engineering application conditions were analyzed and the key technical requirements for the trigger gap were clarified. To meet the requirements of high performance triggering, a high voltage pulse type plasma. double-stage succession triggering method is proposed, a coaxial laminated type productized triggering chamber was designed, a test platform for triggering characteristics was set up, a test study of triggering performance was carried out, and a method for online monitoring of triggering performance by monitoring the voltage change of the energy storage capacitor during the triggering process was proposed. The research results show that the minimum triggerable voltage is 50 kV, the trigger time delay is 0.3 ms, and the no-load trigger life is 1800 times. In order to meet the requirements of large direct-current flow and fast insulation recovery, the design of the main electrode of the spin-arc was completed based on the principle of transverse magnetic electrode spin-arc, and the electric field and spin-arc simulation was carried out. The results show that the arc is capable of rotating at high speed along the edge of the main electrode, recovering to withstand 1.5 times the rated voltage in 0.1 s after 30 kA/50 ms through-current, and withstanding 50 through-current cycles. Based on the solution of the above key issues, the structural design of the dual redundant plasma jet trigger gap body and the high potential measurement and control package was completed. The prototype has been developed and verified by the third party performance tests. The key technical indicators of insulation, triggering and through-current fully can meet the requirements of the Baijiang project and will be applied in the project.