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Description
The two-dimensional (2D) rotary axisymmetric model is used to describe the formation and development of cathode spot on pure Cu and CuCr alloy in vacuum arc. The model includes hydrodynamic equations and heat transfer equation. Parameters used in this model come from experiments and other researchers’ work. The influence of each parameter is analyzed and the simulation results are compared with pure metal simulation results. In the simulation, the process of cathode crater, and distribution of temperature are obtained,the depth of cathode crater is from 0.5μm to 1.1μm, the radius of cathode crater is from 1.6μm to 2.6μm, the maximum velocity of droplet is from 200m/s to 600m/s and the maximum temperature is from 3500K to 5000K which is located in the area with radius 0.5~1.5μm. Cathode spot appears on chromium grain only and the ablation on CuCr alloy is the smallest.
In the simulation, On CuCr alloy, cathode spot appears only on chromium grain and compared with pure metal, whether it is pure copper or pure chromium, the cathode crater on alloy is smaller which means under the same conditions, the ablation of the alloy is less than pure metal. The simulation results are in agreement with experiments and other researcher’s simulation on the crater size and liquid metal shape.
In our future works, more factors will be considered, such as thermo-field mitted electrons, backflow ion flux, back-diffused electrons and Lorentz force and so on.