The inductance of the discharge in a spark gap

Abstract.A promising actuator for high-speed flow control, referred to as a Plasma Synthetic Jet (P.S.J), is being studied by the DMAE department of the ONERA, and the Laplace laboratory of the CNRS, in France. This actuator was inspired by the "Sparkjet" device developed by the Johns Hopkins University Applied Physics Laboratory. The PSJ, which produces a synthetic jet with high exhaust velocities, no active mechanical components and no mass flow admission, holds the promise of enabling high-speed flows to be manipulated. With this high velocity jet it is possible to reduce fluid phenomena such as transition and turbulence, thus making it possible to increase an aircraft's performance whilst at the same time reducing its environmental impact. A thermal plasma discharge was created in a micro cavity, causing the gas to be expelled. It is relevant that the velocity and momentum depend on the energy dispersed by the electric discharge. To control the frequency and energy dispersed in the plasma, the Laplace laboratory has developed two high voltage power supply systems. These allow two different types of discharge to be produced, with energy being supplied to the discharge in two different manners. In this paper, we focus on the impact of the power supply on the Plasma Synthetic Jet, and in particular on the role of the rate of energy dissipation in the discharge. In order to estimate the influence of the power supply on the machinery of the actuator, specific experimental techniques were used to investigate the electrical (voltage, current), thermal (Infra-red camera) and aerodynamic (jet duration, isentropic pressure, jet velocity) characteristics. These data sets were used to determine which of the two power supplies was more effective, thus allowing us to reach several conclusions concerning the importance of the energy dissipation rate on the PSJ actuator.1.

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“…The temporal variation of the current and the voltage indicates that the discharge behaves like a spark discharge [31][32][33][34][35][36].…”

Section: Capacitive Power Supplymentioning

confidence: 99%

Influence of the energy dissipation rate in the discharge of a plasma synthetic jet actuator

Belinger

Hardy

Barricau

et al. 2011

J. Phys. D: Appl. Phys.

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“…25 The spark discharge was shown to have an inductive component on the order of 10 nH. 26 Since this value is more than 2 orders of magnitude lower than the total inductance of our discharge circuit, the inductance of the discharge gap was neglected with respect to the total inductance of our discharge circuit. More complete electrical models take into account the capacitance of the electrodes and the inductance of the plasma, along with the capacitance, resistance, and inductance of the used probes.…”

Section: A Electrical Resultsmentioning

confidence: 99%

A time-resolved imaging and electrical study on a high current atmospheric pressure spark discharge

Palomares

Kohut

Galbács

et al. 2015

Journal of Applied Physics

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A time-resolved laser induced fluorescence study on the ion velocity distribution function in a Hall thruster after a fast current disruption Phys. Plasmas 16, 043504 (2009) We present a time-resolved imaging and electrical study of an atmospheric pressure spark discharge. The conditions of the present study are those used for nanoparticle generation in spark discharge generator setups. The oscillatory bipolar spark discharge was generated between two identical Cu electrodes in different configurations (cylindrical flat-end or tipped-end geometries, electrode gap from 0.5 to 4 mm), in a controlled co-axial N 2 flow, and was supplied by a high voltage capacitor. Imaging data with nanosecond time resolution were collected using an intensified CCD camera. This data were used to study the time evolution of plasma morphology, total light emission intensity, and the rate of plasma expansion. High voltage and high current probes were employed to collect electrical data about the discharge. The electrical data recorded allowed, among others, the calculation of the equivalent resistance and inductance of the circuit, estimations for the energy dissipated in the spark gap. By combining imaging and electrical data, observations could be made about the correlation of the evolution of total emitted light and the dissipated power. It was also observed that the distribution of light emission of the plasma in the spark gap is uneven, as it exhibits a "hot spot" with an oscillating position in the axial direction, in correlation with the high voltage waveform. The initial expansion rate of the cylindrical plasma front was found to be supersonic; thus, the discharge releases a strong shockwave. Finally, the results on equivalent resistance and channel expansion are comparable to those of unipolar arcs. This shows the spark discharge has a similar behavior to the arc regime during the conductive phase and until the current oscillations stop. V C 2015 AIP Publishing LLC. [http://dx

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“…For continuous operation it is preferred to use a large air-flow rate, to remove the evaporated electrode material from the gap, preventing it from accumulating inside the switch or on the insulators. Furthermore, according to Persephonis et al, 13 although the inductance of the switch decreases for decreasing gap distance and increasing gas pressure, for a fixed gap distance an increase in pressure results in an increase in inductance.…”

Section: A Operating Regimes For Stable Trigger Performancementioning

confidence: 89%

“…In Ref. 13 it was shown that by decreasing the gap distance, the inductance of the switch decreases. To prevent pre-firing of the switch when the distance is reduced, the spark-gap switch has to be pressurized.…”

Section: Spark-gap Switch Designmentioning

confidence: 99%

Long lifetime, triggered, spark-gap switch for repetitive pulsed power applications

Winands

Liu

Pemen

et al. 2005

Review of Scientific Instruments

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In this article a critical component for pulsed power applications is described: the heavy-duty switch. The design of a coaxial, high repetition rate, large average power, and long lifetime spark-gap switch is discussed. The switch is used with a fail-free LCR trigger circuit. Critical issues for switch design are presented together with experimental results. It is observed that the switch has a good stability, and its lifetime is estimated to be in the order of 10 10 shots ͑ϳ10 6 C͒ at 10 J / pulse, 60 kV and 100 ns pulses. Measurements were performed with 20 and 34 kV average switching voltage ͑100 ns pulses, energy per pulse 0.4 and 0.75 J, respectively͒. For up to 450 pulses/ s ͑pps͒, pre-firing can be prevented by increasing the gap pressure ͑up to 2.5 and 7 bars, respectively͒, no gas flush is required. Above 450 pps, up to 820 pps, a forced gas flow of maximal 35 Nm 3 /h, is required for stable operation. Measurements on the time delay and jitter of the switch demonstrate that these values are influenced by pressure, flow, and pulse repetition rate. For 34 kV average switching voltage the time delay and time jitter vary between 35 and 250 and 10 and 80 s, respectively. For 20 kV average switching voltage these values are: 30-160 and 4 -50 s. During a test run of 2.5 h ͑at 100 Hz, 0.75 J / pulse͒ the feasibility of the switch was proved, and the switching voltage jitter was less than 0.7%.

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The inductance of the discharge in a spark gap

Cited by 56 publications

References 6 publications

Influence of the energy dissipation rate in the discharge of a plasma synthetic jet actuator

Influence of the energy dissipation rate in the discharge of a plasma synthetic jet actuator

A time-resolved imaging and electrical study on a high current atmospheric pressure spark discharge

Long lifetime, triggered, spark-gap switch for repetitive pulsed power applications

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