Positive streamers in air and nitrogen of varying density: experiments on similarity laws
By T. Briels, Van Veldhuizen, Ute Ebert. 2008
160 citations recorded by the source corpus.
Positive streamers in ambient air at pressures from 0.013 to 1 bar are investigated experimentally. The voltage applied to the anode needle ranges from 5 to 45 kV, the discharge gap from 1 to 16 cm. Using a ‘slow’ voltage rise time of 100–180 ns, the streamers are intentionally kept thin. For each pressure p, we find a minimal diameter dmin. To test whether streamers at different pressures are similar, the minimal streamer diameter dmin is multiplied by its pressure p; we find this product to be well approximated by p · dmin = 0.20 ± 0.02 mm bar over two decades of air pressure at room temperature. The value also fits diameters of sprite discharges above thunderclouds at an altitude of 80 km when extrapolated to room temperature (as air density rather than pressure determines the physical behaviour). The minimal velocity of streamers in our measurements is approximately 0.1 mm ns−1 = 105 m s−1. The same minimal velocity has been reported for tendrils in sprites. We also investigate the size of the initial ionization cloud at the electrode tip from which the streamers emerge, and the streamer length between branching events. The same quantities are also measured in nitrogen with a purity of approximately 99.9%. We characterize the essential differences with streamers in air and find a minimal diameter of p · dmin = 0.12 ± 0.02 mm bar in our nitrogen.
Subfields: Astronomy and Astrophysics, Electrical and Electronic Engineering, Radiology, Nuclear Medicine and Imaging
View Paper: https://www.semanticscholar.org/paper/179c582a0da1e607c6211a0c50b33dc50527dca3
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Citations in the corpus
- Review of recent results on streamer discharges and discussion of their relevance for sprites and lightning (2010, methodology): “Therefore the similarity laws do not hold in the immediate neighborhood of electrodes as discussed and illustrated by Briels et al. [2008b] ; the role of a needle electrode during streamer inception at different densities is illustrated in the photographs by Briels et al. [2008c].”
- The physics of streamer discharge phenomena (2020, methodology): “[65] found that despite the variation of streamer diameters”
- Optical diagnostics of streamer discharges in atmospheric gases (2014, background): “In a subsequent study [133], the minimum diameter of positive streamers was determined over a wide range of pressures in air (p × dmin = 0.”