Pre-breakdown ionization processes and impulsive breakdown characteristics of gases

Rights statement
Awarding institution
  • University of Strathclyde
Date of award
  • 2023
Thesis identifier
  • T16527
Person Identifier (Local)
  • 201760529
Qualification Level
Qualification Name
Department, School or Faculty
  • Global warming has become a central issue in the problem of environmental protection. Sulphur hexafluoride (SF6) has excellent insulation and recovery characteristics; however, this gas has significant Global Warming Potential ⁓23,900 times higher than CO2. Therefore, to reduce negative environmental impact caused by SF6 when this gas is released into atmosphere, the power and pulsed power industries are actively looking for alternative gases which can be used as insulating fluids in high voltage power and pulsed power systems. Therefore, there is an urgent need to establish breakdown properties and characteristics of common and environmentally friendlygases in different topologies and energisation regimes. Thus, further understanding of the transient pre-breakdown processes, dynamic properties of plasma streamers and experimental breakdown characteristics of common and environmentally friendly gases in a wide range of normalised pressures and electric fields is required. The present thesis addresses this issue through: (i) the systematic investigation and analysis of the swarm characteristics of air, N2, CO2, and SF6, (ii) the development of analytical models for investigation of fast ionization process in these gases, including drift-diffusion and kinetic models, (iii) the experimental investigation of the impulsive breakdown properties of air, N2, CO2 stressed with fast, sub-s high voltage impulses with a rise time of up to ~50 ns in the pressure range from 6.5 kPa to 405 kPa, and (iv) the analysis of breakdown properties of humid air with selected relative humidity. The present work has conducted a comprehensive analytical, computational and experimental investigation of transient events in common and environmentally friendly gases and their impulsive breakdown characteristics. The breakdown characteristics of the investigated gases have been obtained, and these data are presented as field-distance and time-field characteristics. These obtained results willhelp to optimize gaseous insulation for different power and pulsed power applications, the findings will contribute to a better understanding of the development of the fast pre-breakdown processes in gases. Thus, it will help to develop different gas-insulated components for the HV power and pulsed power systems, such as fast plasma closing switches filled with environmentally friendly gases and gas-insulated systems.
Advisor / supervisor
  • MacGregor, Scott
  • Timoshkin, Igor
Resource Type
Date Created
  • 2022