Experimental study on hard x-rays emitted from metre-scale negative discharges in air

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We investigate the development of metre long negative discharges and focus on their x-ray emissions. We describe appearance, timing and spatial distribution of the x-rays. They appear in bursts of nanosecond duration mostly in the cathode area. The spectrum can be characterized by an exponential function with 200¿keV characteristic photon energy. With nanosecond-fast photography we took detailed images of the pre-breakdown phenomena during the time when x-rays were registered. We found bipolar discharge structures, also called 'pilot systems', in the vicinity of the cathode. As in our previous study of x-rays from positive discharges, we correlate the x-ray emission with encounters between positive and negative streamers. We suggest that a similar process is responsible for x-rays generated by lightning leaders.
Original languageEnglish
Pages (from-to)025205-1/13
Number of pages14
JournalJournal of Physics D: Applied Physics
Issue number2
Publication statusPublished - 21 Jan 2015


  • discharge
  • x-ray
  • lightning
  • streamer
  • leader
  • experimental
  • pilot system


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