Analysis of the Arcing Processes of DC Arc in Liquid Nitrogen

With the increasingly urgent demand for high-power density transmission of electrical energy, the combination of multiple types of high-temperature superconducting devices has emerged as a highly promising next-generation advanced power supply technology for superconducting DC power systems. Resistive superconducting fault current limiters (SFCLs) exhibit rapid fault response and strong current-limiting capabilities, serving as key equipment for fault suppression and clearance in superconducting DC power systems. As the refrigerant and insulating medium for resistive SFCLs, liquid nitrogen demonstrates considerable potential for DC arc extinction, offering the possibility of realizing “superconducting fault current limiter-liquid nitrogen interruption integration,” thereby providing support for combined applications of superconducting power equipment at the system level. However, a comprehensive understanding of the physical processes of DC arc development and extinction in liquid nitrogen is still lacking, and the evolutionary laws of arc characteristics under the coexistence state of gas, liquid, and plasma phases remain unclear. The research objective of this paper is to elucidate the physical processes of DC arc combustion in liquid nitrogen and to identify the key factors influencing arc characteristics. Initially, a measurement platform for basic electrics, fluid pressure, and arc imaging in liquid nitrogen arcs was constructed, and experimental investigations were conducted into the variations of basic parameters such as fluid pressure and arc voltage during arc combustion in liquid nitrogen. The research results indicate that the arc voltage in liquid nitrogen exhibits a linear increase, characterized by three developmental stages of oscillation, rapid decline, and fluid pressure increase, which is identified as the primary cause of sustained arc voltage development. The peak value and oscillation amplitude of arc voltage increase with the arc current. Combined with arc impact analysis, the phase change cooling of liquid nitrogen and the development of nitrogen gas clusters are believed as key factors influencing the characteristics of liquid nitrogen arcs. The findings of this study can provide a research foundation for the design of DC switches using liquid nitrogen as an arc extinguishing medium.