Electromagnetic Simulation and Analysis of a Rotary-Arc Gap Switch

The electrode erosion is a serious problem for pulsed power switches working under high current. A rotary-arc gap switch (RAG) is the switch form that can reduce the electrode erosion through the fast rotation of the arc. A RAG with a coaxial cylindrical structure is designed in this paper, mainly composed of two electrodes and two coils. The finite-element-analysis software Ansoft is used to simulate and analyze the electromagnetic characteristics of the switch. The simulation shows that the distribution of the magnetic field generated by the coils is symmetric and is with a mirrorlike structure. The existence of the electrodes will weaken the magnetic field because of the reaction of the eddy currents. Cutting the electrodes is the way to solve the problem, and cutting the outer electrode is much more valid than cutting the inner electrode. However, the number of slots in the outer electrode does not influence much. When the RAG works, the arc will rotate fast around the inner electrode due to the action of a Lorentz force under the axial magnetic field, as is convenient to reduce the electrode erosion and prolong the life of the switch. The high-current experiments show that the RAG can withstand very high current and very high charge transfer with very slight electrode erosion.