Microparticle‐initiated electron emission and subsequent gas breakdown

Abstract

AbstractMicroparticle‐initiated breakdown phenomena in gas gap have obtained extensive research interest and micro‐gap discharge is convinced to play a key role. To illustrate this, this paper focused on microparticle‐initiated electron emission and subsequent gas breakdown process in a nitrogen gap. Analytic results of the electric field distribution between the charged microparticle and electrode surface are obtained by using the image method first. Results indicate that for the typical microparticles (R < 20 μm) from electrode erosion, when the micro‐gap distance h is lower than 2 μm, the maximum enhanced field strength could exceed 3 × 107 V/m. Based on this, a two‐dimensional axis‐symmetry numerical model is calculated by using the particle‐in‐cell coupling with Monte Carlo method and the charged microparticle is positioned near anode and cathode separately. In both cases, the local enhanced electron emission between microparticle and electrode surface is the key to initiate the final gas breakdown. The breakdown near cathode is electron‐dominated, which could accomplish in several nanoseconds. The breakdown near anode is ion‐dominated, which needs stronger field enhancement factor or longer breakdown time and would be harder to occur in reality.