Simulations of positive streamers in air in different electric fields: steady motion of solitary streamer heads and the stability field

Abstract

We simulate and characterize positive streamers in ambient air in homogeneous background electric fields from 4.5 to 26 kV/cm in a 4 cm gap. They can accelerate or decelerate depending on the background electric field. Many experiments have shown that a streamer keeps propagating in a stable manner in the so-called stability field of 4.5 to 5 kV/cm. Our fluid streamer simulations in STP air show that: (1) In a homogeneous field larger than 4.675 kV/cm, a single streamer accelerates, and in a lower field, it decelerates and eventually stagnates with a small radius and very high field enhancement. (2) In a field of 4.675 kV/cm, the streamer head propagates with an approximately constant velocity of 6.7 x 10${}^4$ m/s and an optical radius of 55 $\mu$m over distances of several centimeters as a stable coherent structure. These values for the radius and velocity agree well with measurements of so-called minimal streamers. (3) Behind the uniformly translating streamer head, the channel conductivity decreases due to electron attachment and recombination, and the electric field returns to its background value about 1 cm behind the head. The propagation behavior of the solitary streamer agrees with the original definition of the stability field, which is the homogeneous field in which a streamer can propagate with a constant speed and shape.

References in corpus (4)

• Positive and negative streamers in ambient air: measuring diameter, velocity and dissipated energy
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• Review of recent results on streamer discharges and discussion of their relevance for sprites and lightning
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Cited by in corpus (5)

• A computational study of accelerating, steady and fading negative streamers in ambient air
• A computational study of steady and stagnating positive streamers in N2-O2 mixtures
• A computational study on the energy efficiency of species production by single-pulse streamers in air
• Estimating the properties of single positive air streamers from measurable parameters
• Macroscopic parameterization of positive streamer heads in air