In order to accurately diagnose the characteristics of vacuum arcs and to further investigate their key regulatory mechanisms

thereby improving the performance and reliability of vacuum switching devices

this study established an optical diagnostic system for Cu II (Cu+) excitation temperature in vacuum arcs based on emission spectroscopy

and analyzed the 2D spatiotemporal distribution of Cu+ excitation temperature and its dependence on current amplitude

contact gap

and contact material. Experimental results show the near-anode temperature synchronizes with the sinusoidal current waveform

while the near-cathode temperature remains stable at (12 500±1 000) K for 0~6 ms before decreasing with current density. The arc column temperature exhibits distinct current-dependent characteristics with trapezoidal variation at 8 kA and U-shaped variation at 14/20 kA. Spatially

the axial temperature distribution displays a linear monotonic increase from anode to cathode at 8 kA

evolving into a pattern with higher temperatures at both ends at 14/20 kA

while the radial distribution transforms from a central high-temperature zone to an edge annular high-temperature zone with increasing current. Current amplitude affects temperature differently across regions: near-anode temperature increases linearly with current

and arc column shows opposite trend

while near-cathode temperature rises below 16 kA then stabilizes

demonstrating saturation. Reducing contact gap forms distinct jet structures with 25%~30% higher core temperatures. Increasing Cr content significantly lowers Cu+ excitation temperature. These findings provide an experimental basis for understanding and controlling vacuum arc plasma characteristics.