Understanding electric discharges through computer simulations

December 14, 2023

Baohong Guo defended his PhD thesis at the Department of Applied Physics and Science Education on December 7th.

Photo: iStockPhoto

Streamer discharges can develop in gases or air when they are exposed to electric fields, and they can propagate at 100 to 1000 km/s. They form the initial phase of other electric discharges, such as electric sparks and lightning. Streamers also occur in diverse technological applications, such as in plasma-chemical applications like gas processing and plasma medicine. For his PhD research, Baohong Guo used advanced numerical simulations are used to study streamer discharges.

Virtual laboratories

As part of his PhD research, Baohong Guo used numerical simulations as virtual laboratories, which enabled him and his collaborators to probe the fundamental physics behind streamers and shed light on experimental findings.

However, streamers are quite challenging to simulate due to their complex, transient, and nonlinear nature.

Energy efficiency and the environment

One aspect explored is the energy efficiency of chemical processes triggered by streamer discharges, which is important for industrial applications.

Positive streamers are found to be more energy-efficient than negative ones. Guo’s findings indicate that energy efficiency can be improved by using shorter voltage pulses and higher voltages.

Another topic addressed in Guo’s thesis is the replacement of the insulating gas SF6, which is now widely used in the high-voltage industry but which is an extremely strong greenhouse gas.

This motivated the investigation of streamer discharges in C4F7N-CO2 mixtures, which are an environmentally friendly alternative to SF6. Understanding how streamer discharges behave in these mixtures is important for developing the next generation of high-voltage switchgear.

Inhomogeneous gas density

The effect of an inhomogeneous gas density on streamer propagation is also studied by Guo. Detailed 3D simulations show that streamers can easily propagate into lower-density gas but branch out into flower-like patterns when entering higher-density gas.

Finally, Guo also studied the influence of streamer polarity by comparing different propagation modes for positive and negative discharges.

Altogether, his research contributes to a deeper understanding of electric discharge phenomena and their potential applications.

Title of PhD-thesis: Simulating Positive and Negative Streamer Discharges in Air and in Strongly Attaching Gases. Supervisors: Ute Ebert (Centrum Wiskunde & Informatica, Eindhoven University of Technology), Jannis Teunissen (Centrum Wiskunde & Informatica). Other main parties involved: China Scholarship Council.