Predictive numerical modelling and analysis of the formation of arc attachment modes in high-current vacuum arcs - VArcA

• Applicants: Dr. Sergey Gortschakow; Tao Zhu, Ph.D.
• Subject Area: Electrical Energy Systems, Power Management, Power Electronics, Electrical Machines and Drives
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 548964199

To promote applications of vacuum arc based technology a deeper understanding of physical processes, which control the arc plasma and its interaction with surrounding medium (electrodes, walls) is necessary. Depending on dominant physical processes within the arc plasma and electrode activity, experimental observations have revealed a number of different attachment modes on the anode and the cathode. Despite extensive research, some important aspects of mode formation are not well understood. Furthermore, the methods for controlling of the mode appearance and transitions between them are highly desired for optimization of operation regimes in various applications. The knowledge is still lacking on (1) role of excited species, especially for the processes in the vicinity of the electrodes and in the arc fringes; (2) interplay between convection and diffusion fluxes of plasma species; (3) influence of cathode and anode activity on the mode formation; (4) effects of electrode movement, temporal variation of input power as well as the role of external magnetic field during the formation of different attachment modes; (5) the degree to which a vacuum arc model can accurately anticipate the attachment modes in the experiments. The proposed project aims to address these five aspects. To this end, the proposed work will focus on the study of the high-current vacuum arc constriction process and anode attachment mode transitions with the following key objectives: (i) to clarify the relationship between the different anode attachment modes and the different species transport processes, especially the comparative analysis of convective and diffusive fluxes for the various species; this will be performed by means of a self-consistent DC vacuum arc model; (ii) to clarify the role of excited species and chemical reaction pathways in the formation of the arc attachment modes; this will be conducted by using a collisional-radiative model; (iii) to find out the role of the energy, momentum and mass transfer processes involved in the electrode regions in the arc column constriction process; this will be fulfilled by means of a parametric study; (iv) to investigate the influence of the electrode motion and the AC power change process as well as the external magnetic field on the constriction process; this will be completed by a transient numerical model, which extends the developed DC model; (v) to detect the predictive performance of the developed vacuum arc model; this will be performed by detailed experimental study, which will provide reliable data for model validation (like e.g. particle densities, temperature of plasma components, surface temperature). The results of the investigations will advance the knowledge of the fundamental mechanisms governing the operation of the vacuum arc.

• DFG Programme: Research Grants