• Conductivity and capacitance of streamers in avalanche model for streamer propagation in dielectric liquids 

      Madshaven, Inge; Hestad, Øystein Leif Gurandsrud; Unge, Mikael; Hjortstam, Olof; Åstrand, Per-Olof (Journal article; Peer reviewed, 2019)
      Propagation of positive streamers in dielectric liquids, modeled by the electron avalanche mechanism, is simulated in a needle–plane gap. The streamer is modeled as an RC-circuit where the channel is a resistor and the ...
    • Field dependent conductivity of n-pentane 

      Hestad, Øystein Leif Gurandsrud; Linhjell, Dag; Lundgaard, Lars Esben; Samseth, Jarl Ø.; Unge, Mikael (Chapter, 2017)
      A sensitive differential charge measurement technique was used to measure the conduction current from a sharp needle in a needle plane geometry in n-pentane. The current was measured at voltages up to the threshold for ...
    • Field-dependent molecular ionization and excitation energies: Implications for electrically insulating liquids 

      Davari, Nazanin; Åstrand, Per-Olof; Unge, Mikael; Lundgaard, Lars Esben; Linhjell, Dag (Journal article; Peer reviewed, 2014)
      Themolecular ionization potential has a relatively strong electric-field dependence as compared to the excitation energies which has implications for electrical insulation since the excited states work as an energy sink ...
    • Local Field Factors and Dielectric Properties of Liquid Benzene 

      Davari, Nazanin; Daub, Christopher David; Åstrand, Per-Olof; Unge, Mikael (Journal article; Peer reviewed, 2015)
      Local electric field factors are calculated for liquid benzene by combining molecular dynamic simulations with a subsequent force-field model based on a combined charge-transfer and point-dipole interaction model for the ...
    • Modeling the transition to fast mode streamers in dielectric liquids 

      Madshaven, Inge; Åstrand, Per-Olof; Hestad, Øystein Leif Gurandsrud; Unge, Mikael; Hjortstam, O. (Chapter, 2017)
      A simplified model for photoionization, modeling fast streamer propagation, is combined with an existing model for slow streamers, based on electron avalanches. Transitions from fast mode to slow mode, and from slow mode ...
    • Photoionization model for streamer propagation mode change in simulation model for streamers in dielectric liquids 

      Madshaven, Inge; Hestad, Øystein Leif Gurandsrud; Unge, Mikael; Hjortstam, Olof; Åstrand, Per-Olof (Journal article; Peer reviewed, 2019)
      Radiation is important for the propagation of streamers in dielectric liquids. Photoionization is a possibility, but the effect is difficult to differentiate from other contributions. In this work, we model radiation from ...
    • Simulation model for the propagation of second mode streamers in dielectric liquids using the Townsend-Meek criterion 

      Madshaven, Inge; Åstrand, Per-Olof; Hestad, Øystein; Ingebrigtsen, Stian; Unge, Mikael; Hjortstam, Olof (Journal article; Peer reviewed, 2018)
      A simulation model for second mode positive streamers in dielectric liquids is presented. Initiation and propagation is modeled by an electron-avalanche mechanism and the Townsend–Meek criterion. The electric breakdown is ...
    • Time to breakdown studies for liquids of different physico-chemical nature 

      Aakre, Torstein Grav; Lundgaard, Lars Esben; Unge, Mikael (Chapter; Peer reviewed, 2017)
      An automated setup for testing dielectric performance of liquids in a small point-to-plane gap is presented. It provides step voltages with rise times around 30 ns, with amplitudes up to 90 kV. Breakdown studies of thirteen ...