Cu-Y, Cu-La and Cu-Ba alloys' microstructure and ablation behavior discharging in air and SF6

High power arc heaters and high voltage disconnectors discharge for a long time. Their cathodes ablate severely. The low work function elements Y, Ba and La were added to pure copper respectively with contents at. 0.3–3%. These alloys' microstructure and ablation behavior discharging in air and SF6 were studied. These alloys consist of the copper phase and the alloy phase. Arc tends to preferentially discharge on the alloy phase. Y, Ba and La can reduce the size of the ablation craters and the sputtered particles, and make the arc spot surface smoother. The arc spots on the cathodes tend to move quickly in SF6, while remain more fixed in air. The arc spots are smoother and the supttered particles are finer when discharging in SF6 than in air. The voltage-discharge distance curves have infection points and the voltage maintains a linear relationship with the discharge distance before and after the infection points. The appearance of the infection point is related to different elements are ionized at different discharge distances. The arc's resistivity is lower and the zero voltage drop is higher when discharging in SF6 than in air.