Circuit dependence of the diameter of pulsed positive streamers in air

Briels, Tmp Tanja; Kos, J. F.; Veldhuizen, van Em Eddie; Ebert, Ute

doi:10.1088/0022-3727/39/24/016

Cited by 108 publications

(187 citation statements)

References 29 publications

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“…The minimal diameter of positive streamers in our simulations is about 0.2 mm, identical to the minimal diameter reported in experiments [30,31,2]. It should be noted, however, that the definition of the radius might differ between experiments and simulations as discussed in section 4.3.…”

Section: Diametersupporting

confidence: 87%

Positive and negative streamers in ambient air: modelling evolution and velocities

Luque

Ratushnaya

Ebert

2008

J. Phys. D: Appl. Phys.

247

190

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Abstract. We simulate short positive and negative streamers in air at standard temperature and pressure. They evolve in homogeneous electric fields or emerge from needle electrodes with voltages of 10 to 20 kV. The streamer velocity at given streamer length depends only weakly on the initial ionization seed, except in the case of negative streamers in homogeneous fields. We characterize the streamers by length, head radius, head charge and field enhancement. We show that the velocity of positive streamers is mainly determined by their radius and in quantitative agreement with recent experimental results both for radius and velocity. The velocity of negative streamers is dominated by electron drift in the enhanced field; in the low local fields of the present simulations, it is little influenced by photo-ionization. Though negative streamer fronts always move at least with the electron drift velocity in the local field, this drift motion broadens the streamer head, decreases the field enhancement and ultimately leads to slower propagation or even extinction of the negative streamer. Positive and negative streamers in ambient air: modeling evolution and velocities 2

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Section: Diametersupporting

confidence: 87%

Positive and negative streamers in ambient air: modelling evolution and velocities

Luque

Ratushnaya

Ebert

2008

J. Phys. D: Appl. Phys.

247

190

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“…The three supplies together cover the voltage range from 5 to 96 kV, their ranges overlap and we find the resulting streamer properties to depend continuously on the voltage, independently of the used supply. We also perform control experiments with one slower voltage supply to further confirm the statement in [32] that power supplies will create similar streamer patterns only if their voltage rise time, peak voltage and internal resistance are similar.…”

Section: Introductionmentioning

confidence: 63%

“…‡ As a short consideration -e.g., of the example for a charged sphere -shows, the electric field close to the strongly curved electrode is mostly determined by voltage and electrode geometry and rather independent of the distance to some distant grounded electrode. It is therefore physically evident and has been confirmed by experiments [31,32], that streamer inception and initial propagation is determined by applied voltage and electrode geometry, and not by some hypothetical average field within the complete discharge gap. The streamers start in a high field region and consecutively expand into a region with decreasing field.…”

Section: Introductionmentioning

confidence: 72%

Positive and negative streamers in ambient air: measuring diameter, velocity and dissipated energy

Briels

Kos

Winands

et al. 2008

J. Phys. D: Appl. Phys.

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253

306

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Abstract. Positive and negative streamers are studied in ambient air at 1 bar; they emerge from a needle electrode placed 40 mm above a planar electrode. The amplitudes of the applied voltage pulses range from 5 to 96 kV; most pulses have rise times of 30 ns or shorter. Diameters, velocities and energies of the streamers are measured. Two regimes are identified; a low voltage regime where only positive streamers appear and a high voltage regime where both positive and negative streamers exist. Below 5 kV, no streamers emerge. In the range from 5 to 40 kV, positive streamers form, while the negative discharges only form a glowing cloud at the electrode tip, but no streamers.

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“…On the other hand, recent sprite observations [13] as well as streamer experiments ( [14], Fig. 7, [11], Fig. 6) also show the opposite: streamers attract each other and coalesce.…”

Section: Pacs Numbersmentioning

confidence: 91%

Interaction of Streamer Discharges in Air and Other Oxygen-Nitrogen Mixtures

2008

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The interaction of streamers in nitrogen-oxygen mixtures such as air is studied. First, an efficient method for fully three-dimensional streamer simulations in multiprocessor machines is introduced. With its help, we find two competing mechanisms how two adjacent streamers can interact: through electrostatic repulsion and through attraction due to nonlocal photo-ionization. The non-intuitive effects of pressure and of the nitrogen-oxygen ratio are discussed. As photo-ionization is experimentally difficult to access, we finally suggest to measure it indirectly through streamer interactions. PACS numbers:Streamer discharges are fundamental building blocks of sparks and lightning in any ionizable matter; they are thin plasma channels that penetrate nonconducting media suddenly exposed to an intense electric field. They propagate by enhancing the electric field at their tip to a level that facilitates an ionization reaction by electron impact [1,2]. Streamers are also the mechanism underlying sprites [3,4,5]; these are large atmospheric discharges above thunderclouds that, despite being tens of kilometers wide and intensely luminous, were not reported until 1990 [6]. Although the investigation of streamers concentrates mainly in gaseous media, they have also been studied in dense matter, such as semiconductors [7] and oil [8]. Streamers have also received attention in the context of Laplacian-driven growth dynamics [9] and a strong analogy with viscous fingering, in particular Hele-Shaw flows [10], has been established. Both in laboratory [11] and in nature [12], streamers appear frequently in trees or bundles. As their heads carry a substantial net electrical charge of equal polarity that creates the local field enhancement, they clearly must repel each other electrostatically which probably causes the "carrot"-like conical shape of sprites. On the other hand, recent sprite observations [13] as well as streamer experiments ([14], Fig. 7, [11], Fig. 6) also show the opposite: streamers attract each other and coalesce.Up to now, streamer interactions have not been studied much theoretically, and streamer attraction has not been predicted at all. In coarse grained phenomenological models for a streamer tree as a whole [15], the repulsive electrostatic interaction between streamers is taken into account. In a more microscopic, but still largely simplified model, Naidis [16] studied the corrections to the streamer velocity due to electrostatic interaction with neighboring streamers. In [17], two authors of the present letter have studied a microscopic "fluid" model for a periodic array of negative streamers in two spatial dimensions, where they show that shape, velocity and electrodynamics of an array of streamers substantially differs from those of single streamers due to their electrostatic interaction, but attraction or repulsion were excluded by the approach. Due to the difficulty to represent this multiscale process [2] in a numerically efficient manner, only recently it has become possible to simulate streamers in...

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Circuit dependence of the diameter of pulsed positive streamers in air

Cited by 108 publications

References 29 publications

Positive and negative streamers in ambient air: modelling evolution and velocities

Positive and negative streamers in ambient air: modelling evolution and velocities

Positive and negative streamers in ambient air: measuring diameter, velocity and dissipated energy

Interaction of Streamer Discharges in Air and Other Oxygen-Nitrogen Mixtures

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