Electric discharge initiation in water with gas bubbles: A time scale approach

Sponsel, Nicholas L.; Gershman, Sophia; Quesada, Maria Jose Herrera; Mast, Jacob T.; Stapelmann, Katharina

doi:10.1116/6.0001990

Cited by 4 publications

(10 citation statements)

References 43 publications

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“…The agreement of these estimates suggests that power was delivered to the discharge well after the initial voltage pulse. This was consistent with the delayed discharges observed in DI water as detailed in our previous work and in other studies [30,34]. However, several breakdown initiation locations were observed for subsequent pulses in DI water, whereas subsequent pulses expand the central emission node in the gas region of the bubble for the conductive liquid case presented in figure 9.…”

Section: Figure S5supporting

confidence: 92%

“…The experimental setup captured free-flowing bubbles between electrodes in synchronization with a high-voltage (HV) nanosecond pulse (Megaimpulse NPG-18/100k). In work preceding this manuscript, it was demonstrated that breakdown initiated at the anode for both positive (excited electrode) and negative (grounded electrode) biased pulses for this experimental setup [30]. For this reason, a positive pulse was used for all cases.…”

Section: Methodsmentioning

confidence: 99%

“…The ICCD exposure gate was opened prior to the pulse and closed during or after the initial pulse, such that emission intensity for the subsequent time steps are integrated cumulatively. For the first ∼10 ns, emission formed at the tip of the electrode before discharge in the gas was observed and was detailed in [30].…”

Section: Streamer Propagation In DI Watermentioning

confidence: 99%

“…Therefore, comparisons between systems should be made cautiously, keeping in mind that differences introduce variations in breakdown dynamics. Table 2 lists the experimental parameters for several studies including the present work [9,24,25,30].…”

Section: Breakdown In Bubbles: Experimental Comparisonsmentioning

confidence: 99%

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Electrical breakdown dynamics in an argon bubble submerged in conductive liquid for nanosecond pulsed discharges

L Sponsel,

Gershman,

Stapelmann

2023

J. Phys. D: Appl. Phys.

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This study delves into the dynamics of cold atmospheric plasma (CAP) and their interaction within conductive solutions under the unique conditions of nanosecond pulsed discharges (22 kV peak voltage, 10 ns FWHM, 4.5 kV ns-1 rate-of-rise). The research focuses on the electrical response, breakdown, and discharge propagation in an argon bubble, submerged in a NaCl solution of varying conductivity. Full or partial discharges were observed at conductivities of 1.5 μS cm-1 (deionized water) to 1.6 mS cm-1, but no breakdown was observed at 11.0 mS cm-1 when reducing the electrode gap. It is demonstrated that at higher conductivity electric breakdown is observed only when the gas bubble comes into direct contact with the electrode and multiple emission nodes were observed at different timescales. These nodes expanded in the central region of the bubble over timescales longer than the initial high-voltage pulse. This work offers a temporal resolution of 2 ns exposure times over the first 30 ns of the initial voltage pulse, and insight into plasma formation over decaying reflected voltage oscillations over 200 ns.

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Section: Figure S5supporting

confidence: 92%

Section: Methodsmentioning

confidence: 99%

Section: Streamer Propagation In DI Watermentioning

confidence: 99%

Section: Breakdown In Bubbles: Experimental Comparisonsmentioning

confidence: 99%

See 2 more Smart Citations

Electrical breakdown dynamics in an argon bubble submerged in conductive liquid for nanosecond pulsed discharges

L Sponsel,

Gershman,

Stapelmann

2023

J. Phys. D: Appl. Phys.

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“…Imaging was performed under dark conditions to capture only the light emitted from electric breakdown. However, the location of the bubble boundaries was found by utilizing a large image set of bubble positions and shapes taken with a backlight capturing the silhouette of bubbles and electrodes (see section 3) [28]. Over the entirety of the discharge, the emission curved in a manner that suggests surface streamers propagated across the deformed interface of the bubble.…”

Section: Introductionmentioning

confidence: 99%

Plasma breakdown in bubbles passing between two pin electrodes

Pillai

Sponsel

Mast

et al. 2022

J. Phys. D: Appl. Phys.

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The ignition of plasmas in liquids has applications from medical instrumentation to manipulation of liquid chemistry. Formation of plasmas directly in a liquid often requires prohibitively large voltages to initiate breakdown. Producing plasma streamers in bubbles submerged in a liquid with higher permittivity can significantly lower the voltage needed to initiate a discharge by reducing the electric field required to produce breakdown. The proximity of the bubble to the electrodes and the shape of the bubbles play critical roles in the manner in which the plasma is produced in, and propagates through, the bubble. In this paper, we discuss results from a 3-dimensional direct numerical simulation (DNS) used to investigate the shapes of bubbles formed by injection of air into water. Comparisons are made to results from a companion experiment. A 2-dimensional plasma hydrodynamics model was then used to capture the plasma streamer propagation in the bubble using a static bubble geometry generated by the DNS The simulations showed two different modes for streamer formation depending on the bubble shape. In an elliptical bubble, a short electron avalanche triggered a surface ionization wave resulting in plasma propagating along the surface of the bubble. In a circular bubble, an electron avalanche first travelled through the middle of the bubble before two surface ionization waves began to propagate from the point closest to the grounded electrode where a volumetric streamer intersected the surface. In an elliptical bubble approaching a powered electrode in a pin-to-pin configuration, we experimentally observed streamer behavior that qualitatively corresponds with computational results. Optical emission captured over the lifetime of the streamer curve along the path of deformed bubbles, suggesting propagation of the streamer along the liquid/gas boundary interface. Plasma generation supported by the local field enhancement of the deformed bubble surface boundaries is a mechanism that is likely responsible for initiating streamer formation.

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