Cooling-induced cathode-focusing effect in tungsten-based arc: Rim suppression phenomenon and mechanism

• Published in: International journal of heat and mass transfer 2025-04, Vol.239, p.126628, Article 126628
• Main Authors: Liu, ZuMing, Jia, Bohan, Chen, ShaoYong, Jiao, ZiXian, Zhao, XingChuan
• Format: Article
• Language: English
• Subjects: Arc heat source; Cathode; Heat transfer; Numerical simulation; Tungsten electrode
• ISSN: 0017-9310
• DOI: 10.1016/j.ijheatmasstransfer.2024.126628

•Rim suppression phenomenon is first discovered in water-cooled GTA tungsten.•Enhancing cooling degree reduces the tungsten temperature from 5003.02 K to 3911.04 K at 500 A.•Rim suppression runs with slower tungsten oxidation rate and oxides vaporization rate in water-cooled tungsten. Protection of the cathode tip is key for the cathode lifespan in an arc source system. Cooling the tungsten electrode significantly influences the cathode tip temperature field and subsequently affects cathode-arc behavior due to the cooling-induced cathode-focusing (CICF) effect in a tungsten-based arc system. In the research, the cathode phenomenon and tungsten erosion in the CICF arcing system are experimentally observed. Then an arc-electrode model is established to explain the mechanism of tungsten electrode cooling degree on the cathode temperature. The rim formation restriction mechanism is discussed. Results show that enhancing the cooling degree of the tungsten electrode can: (1) greatly lower the tungsten electrode temperature; (2) suppress rim formation near the tungsten tip. The decrease in tungsten electrode temperature and suppression of rim formation is thought to decrease the grind work and prolong the tungsten electrode's service life. This research can provide guidance for increasing the arc energy concentration and improving the tungsten electrode's working environment in an arcing system.