The splitting and threshold currents of vacuum arc cathode spots in axial magnetic fields (AMFs) up to 220 mT are investigated experimentally. Measurements are made on electrodes of Cu and CuCr25 with electrode separations of 2 and 6 mm. The electrode diameter is 30 mm. All the experiments are conducted in a demountable vacuum chamber evacuated continuously by a turbo-molecular pump to a pressure of the order of 10-3 Pa. The spots are photographed using a high-speed digital camera with an exposure time of 2 μs. The AMF is applied by means of two permanent magnets placed symmetrically inside the chamber. The experimental results indicate that the splitting and threshold current decrease in the presence of AMF and tend to certain constant values when the field gets stronger. The splitting and threshold currents are considerably larger than Cu electrodes than those with CuCr25 electrodes. With increasing electrode separation, the splitting current decreases while the threshold current increases. Possible explanations are proposed to account for the experimental observations.

中文翻译：

---

轴向磁场中真空电弧阴极点所载电流的实验研究


通过实验研究了高达 220 mT 的轴向磁场 (AMF) 中真空电弧阴极点的分裂电流和阈值电流。测量是在电极间距为 2 毫米和 6 毫米的 Cu 和 CuCr25 电极上进行的。电极直径为30毫米。所有实验均在可拆卸真空室中进行，真空室由涡轮分子泵连续抽真空至10-3 Pa量级。使用高速数码相机拍摄斑点，曝光时间为2 μs。 AMF 通过对称放置在室内的两个永磁体来施加。实验结果表明，在 AMF 存在的情况下，分裂电流和阈值电流减小，并且当磁场变强时，分裂电流和阈值电流趋于某个恒定值。与 CuCr25 电极相比，Cu 电极的分裂电流和阈值电流要大得多。随着电极间距的增加，分裂电流减小，而阈值电流增加。提出了可能的解释来解释实验观察结果。