Key points are not available for this paper at this time.
This study investigates the insulation breakdown characteristics of superconducting magnets under high vacuum conditions, focusing on the effects of localized vacuum degradation and the material properties of the stabilizer layer used in superconducting wires. To understand the influence of vacuum pressure variations and electrode material on insulation strength, experiments were conducted using spherical electrodes composed of five different materials. These experiments demonstrated how changes in vacuum pressure affect insulation breakdown characteristics, following the pattern of Paschen's curve. A notable decrease in breakdown voltage was observed in mid-vacuum regions, while an increase was seen in high vacuum conditions, underscoring the significant impact of vacuum pressure on insulation breakdown mechanisms. The results also highlighted the role of electrode material's work function in high vacuum conditions, where materials with higher work functions exhibited higher breakdown voltages. This was particularly evident in the comparison of alloys like Brass, which, despite having a high work function, showed lower breakdown voltages due to surface impurities promoting discharge. In contrast, high-strength metals like Stainless Steel demonstrated higher breakdown voltages, attributed to their chemical stability and resistance to oxidation and corrosion.
Shin et al. (Thu,) studied this question.