Microsecond Electrical Breakdown in Water: Advances Using Emission Analysis and Cavitation Bubble Theory

Abstract

Electrical discharges in water are a subject of major interest because of both the wide range of potential applications and the complexity of the processes. This paper aimed to provide significant insights to better understand processes involved during a microsecond electrical discharge in water, especially during the propagation and the breakdown phases. Two different approaches were considered. The first analysis focused on the emission produced by the discharge during the propagation using fast imaging measurements and spatially resolved optical emission spectroscopy. The excited species H, O, and OH were monitored in the whole interelectrode gap. The second analysis concerned the thermodynamic conditions induced by the breakdown of the discharge. The time evolution of the bubble radius was simulated and estimation of the initial pressure of the cavitation bubble was performed using the Rayleigh–Plesset model. Values of about 1.7 × 107 Pa and 1.2 × 108 Pa were reported for the cathode and anode regimes, respectively. This multidisciplinary approach constitutes a new step to obtain an accurate physical and chemical description of pin-to-pin electrical discharges in water.

Modulating SARS-CoV-2 Spike Protein Reactivity through Moderate Electric Fields: A Pathway to Innovative Therapies

“…In essence, our choice of E-field strength and exposure time reflects a delicate balance between targeting the protein's energy barriers, ensuring safety for living organisms, and harnessing the potential for a meaningful conformational change. Furthermore, the E-field strengths (ranging from 1 to 100 kV/cm) adhere to a range well below the threshold for a dielectric breakdown of water, 30 ensuring both the safety and applicability of this approach. Remarkably, E-field strengths within this range find widespread application in various industrial contexts, including food processing, where they are effectively employed to inactivate pathogens.…”

Characteristic simulation of underwater microsecond high-current pulsed arc discharge plasma

“…where ρ 0 is the density of the liquid medium in the undisturbed region, α and β are coefficients, α = 300.1 MPa and β = 300 MPa [29]. The time-varying impedance model of the arc channel can be established by combining equation ( 2), equations ( 4)- (13) to solve for the time-varying parameters such as current, radius, particle number density and temperature.…”

“…This includes capturing images of the arc channel morphology and shockwave wavefront using techniques such as shadowgraphy, schlieren imaging, and high-speed photography [8][9][10]. For underwater pulsed corona discharges, spark discharges, and bubble discharges of low energy and intensity, emission spectroscopy has been employed for diagnosing the electron density and temperature of the plasma [11][12][13][14][15][16].…”

Spectral diagnosis of underwater microsecond high-current pulsed discharge plasma

“…They utilized emission spectral lines to diagnose the electron density, temperature, and spatiotemporal characteristics of the plasma channel. Factors influencing spectroscopic diagnostics were taken into account, and the diagnostic results were used to analyse the chemical reactions generated by the discharges [6][7][8][9][10][11]. However, since underwater pulsed arc discharge usually operates in isolated pulse mode, and the pre-breakdown time and discharge intensity are random, it is more appropriate to analyse the spectra of each individual discharge, rather than the cumulative spectra of repeated frequency discharges.…”