Numerical simulation of low-current vacuumarc jet considering anode evaporation in different axial magnetic fields |
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Affiliation: | State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, Xi'an 710049, People's Republic of China; |
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Abstract: | As the main source of the vacuum arc plasma, cathode spots (CSs) play an important role on the
behaviors of the vacuum arc. Their characteristics are affected by many factors, especially by the
magnetic field. In this paper, the characteristics of the plasma jet from a single CS in vacuum arc
under external axial magnetic field (AMF) are studied. A multi-species magneto-hydro-dynamic
(MHD) model is established to describe the vacuum arc. The anode temperature is calculated by
the anode activity model based on the energy flux obtained from the MHD model. The
simulation results indicate that the external AMF has a significant effect on the characteristic of
the plasma jet. When the external AMF is high enough, a bright spot appears on the anode
surface. This is because with a higher AMF, the contraction of the diffused arc becomes more
obvious, leading to a higher energy flux to the anode and thus a higher anode temperature. Then
more secondary plasma can be generated near the anode, and the brightness of the ‘anode spot’
increases. During this process, the arc appearance gradually changes from a cone to a dumbbell
shape. In this condition, the arc is in the diffuse mode. The appearance of the plasma jet
calculated in the model is consistent with the experimental results. |
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Keywords: | vacuum arc plasma jet axial magnetic fields |
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