Abstract:A model of ionization processes in a low-temperature plasma within the cathode region of a vacuum arc is presented. This mathematical model is represented by a system of nonlinear differential equations of drift-diffusion for the electron density and the average energy of second-order electrons. The system of equations was solved by the finite element method in two coordinates in numerical form using the COMSOL Multiphysics software program. It was shown that due to nonequilibrium processes, Langmuir waves app… Show more
“…The contact erosion is determined by the behaviours of the cathode spots, including the development of an individual cathode spot, and the cathode spot dynamics such as the formation of a new cathode spot from the previous one. Therefore, the characteristics of cathode spots have been of great interest in recent years, such as the motion of cathode spots [6,7] and the plasma expansion based on the cathode spot [8].…”
Contact erosion on the cathode of a vacuum arc is determined by the behaviours of the cathode spots, where the plasma-surface interactions take place. A self-consistent model of a single cathode spot is developed in this work based on the Molecular Dynamics method, where an atomic copper substrate in the size of nanometres is built and the contributions to the development of cathode spot from leftover plasma ions, surface electron emission, surface atom emission, back ions, Nottingham heating and Joule heating are integrated. Defined based on the surface temperature distribution, a cathode spot is observed in the simulation results. The surface atom emission, which is the origin of mass loss, can be directly detected by the atoms being isolated from the surface. Two routes of surface atom emission are observed as the sources of mass loss, including evaporation, and atom sputtering or splashing. It is found that in the high-temperature region, atom sputtering or splashing dominates the surface atom emission, which leads to considerable mass losses. The simulation results are consistent with previous experimental and other simulation findings, providing fundamental insights into the cathode spot formation mechanism from a microscopic perspective.
“…The contact erosion is determined by the behaviours of the cathode spots, including the development of an individual cathode spot, and the cathode spot dynamics such as the formation of a new cathode spot from the previous one. Therefore, the characteristics of cathode spots have been of great interest in recent years, such as the motion of cathode spots [6,7] and the plasma expansion based on the cathode spot [8].…”
Contact erosion on the cathode of a vacuum arc is determined by the behaviours of the cathode spots, where the plasma-surface interactions take place. A self-consistent model of a single cathode spot is developed in this work based on the Molecular Dynamics method, where an atomic copper substrate in the size of nanometres is built and the contributions to the development of cathode spot from leftover plasma ions, surface electron emission, surface atom emission, back ions, Nottingham heating and Joule heating are integrated. Defined based on the surface temperature distribution, a cathode spot is observed in the simulation results. The surface atom emission, which is the origin of mass loss, can be directly detected by the atoms being isolated from the surface. Two routes of surface atom emission are observed as the sources of mass loss, including evaporation, and atom sputtering or splashing. It is found that in the high-temperature region, atom sputtering or splashing dominates the surface atom emission, which leads to considerable mass losses. The simulation results are consistent with previous experimental and other simulation findings, providing fundamental insights into the cathode spot formation mechanism from a microscopic perspective.
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