Theoretical description and modelling of low-current arcs at small gap distances

• Applicant: Dr. Margarita Baeva
• Subject Area: Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: from 2017 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 390828847

The interdisciplinary importance of arc plasmas is today unequivocally demonstrated in many industrial processes and devices. However, the understanding of the physical mechanisms in electric arcs and their complexity is still incomplete. Assumptions such as equilibrium conditions, drift-diffusion approximation, simple form of Ohm law among others are often made in order to simplify the description of the strongly coupled and non-linear physical problem. These assumptions fail in particular at low current (below 50 A) and short arc length (below 2 mm). This project is aimed at advanced non-equilibrium description and modelling of low-current electric arcs of short length and their interaction with the electrodes. A thorough analysis of the physical processes and arc plasma properties will provide knowledge about the spatial and temporal behavior of the arc when its length is reduced to only a few millimeters. In particular, the modelling will enable us to study the degree to which these arc plasmas have departed from thermal and chemical equilibrium. The main research objective of the project is the development of a self-consistent non-equilibrium model for short-length arc plasmas. This model should also be capable of covering a larger current range (down to a few amperes), it will include the electrodes, and a proper matching of the quasi-neutral plasma with the multi-species space-charge sheaths adjacent to the electrodes. No model with these capabilities has been developed so far, and it is needed in order to significantly improve the physical understanding of short-length arc plasmas encountered in various applications. A multi-scale analysis of the near- electrode regions as well as a study of the spatial behavior of the arc plasma due to shortening of the arc length are further objectives of the project. Project achievements are expected to be advantageous from a technological point of view: established processes like short and micro arc welding, new processes like generative manufacturing with arc welding devices, and the development of low-voltage contacts and switching devices might benefit from new insights and modelling capability. The wide experience of the applicant in plasma modelling and her most recent investigations dedicated to self-consistent and non-equilibrium modelling of arc plasma are advantageous for the project success.

• DFG Programme: Research Grants
• Co-Investigator: Dr. Dirk Uhrlandt