Investigation of the initial phases of nanosecond discharges in liquid water

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61389021%3A_____%2F20%3A00531307" target="_blank" >RIV/61389021:_____/20:00531307 - isvavai.cz</a>

Nalezeny alternativní kódy

RIV/00216224:14310/20:00114468

Výsledek na webu

<a href="https://iopscience.iop.org/article/10.1088/1361-6595/ab87b7" target="_blank" >https://iopscience.iop.org/article/10.1088/1361-6595/ab87b7</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1088/1361-6595/ab87b7" target="_blank" >10.1088/1361-6595/ab87b7</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Investigation of the initial phases of nanosecond discharges in liquid water

Popis výsledku v původním jazyce

In this work, we examine initial phases of micro-discharges produced in deionised water by high-voltage (HV) pulses of nanosecond duration. We apply opto-electrical diagnostics with extremely high temporal (down to 30 ps) as well as spatial (down to 1 μm) resolution. Frozen interferometric and shadowgraph images show three distinct events. The first, the subcritical (no-discharge) event, is characterised by periodic perturbations of the index of refraction which depart from the anode surface and are pulled away at the speed of sound as an expanding envelope defined by the shape of the anode tip. One-dimensional hydrodynamic modelling of the subcritical phase under conditions mimicking curvatures of real anode tips reveals basic characteristics of perturbations caused by dynamic balance between the hydrostatic and electrostrictive pressures consistent with experimental observations. The second, the dark or non-luminous discharge event, is characterised by the onset of a few isolated very tiny tree-like structures growing from the anode tip. Depending on the HV amplitude, the initial structures occur with a delay of ∼2-3 ns after onset of the HV pulse and subsequently expand with average velocity of ∼1 ± 105-2 ± 105 m s-1, creating very dense bush-like structures made of thin hair-like filaments in a few nanoseconds. The third, the luminous discharge event, follows (nearly simultaneously) the dark discharge event and unveils much simpler tree-like morphology determined by the extension of non-luminous bush-like structures. Characteristic dimensions of observed events range from about 1 μm (typical diameter of non-luminous filaments) to tens of micrometres (characteristic diameters of luminous filaments). Furthermore, we address a possible role of microbubbles developing in the anode region due to the periodic HV pulses and verify that the UV-vis-NIR spectrometric signatures of the luminous phase notably change when replacing non-degassed deionised water with degassed.

Název v anglickém jazyce

Investigation of the initial phases of nanosecond discharges in liquid water

Popis výsledku anglicky

In this work, we examine initial phases of micro-discharges produced in deionised water by high-voltage (HV) pulses of nanosecond duration. We apply opto-electrical diagnostics with extremely high temporal (down to 30 ps) as well as spatial (down to 1 μm) resolution. Frozen interferometric and shadowgraph images show three distinct events. The first, the subcritical (no-discharge) event, is characterised by periodic perturbations of the index of refraction which depart from the anode surface and are pulled away at the speed of sound as an expanding envelope defined by the shape of the anode tip. One-dimensional hydrodynamic modelling of the subcritical phase under conditions mimicking curvatures of real anode tips reveals basic characteristics of perturbations caused by dynamic balance between the hydrostatic and electrostrictive pressures consistent with experimental observations. The second, the dark or non-luminous discharge event, is characterised by the onset of a few isolated very tiny tree-like structures growing from the anode tip. Depending on the HV amplitude, the initial structures occur with a delay of ∼2-3 ns after onset of the HV pulse and subsequently expand with average velocity of ∼1 ± 105-2 ± 105 m s-1, creating very dense bush-like structures made of thin hair-like filaments in a few nanoseconds. The third, the luminous discharge event, follows (nearly simultaneously) the dark discharge event and unveils much simpler tree-like morphology determined by the extension of non-luminous bush-like structures. Characteristic dimensions of observed events range from about 1 μm (typical diameter of non-luminous filaments) to tens of micrometres (characteristic diameters of luminous filaments). Furthermore, we address a possible role of microbubbles developing in the anode region due to the periodic HV pulses and verify that the UV-vis-NIR spectrometric signatures of the luminous phase notably change when replacing non-degassed deionised water with degassed.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10305 - Fluids and plasma physics (including surface physics)

Projekt

<a href="/cs/project/GA18-04676S" target="_blank" >GA18-04676S: Základní mechanismy nanosekundového výboje v kapalné vodě</a><br>

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2020

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Plasma Sources Science & Technology

ISSN

0963-0252

e-ISSN

—

Svazek periodika

29

Číslo periodika v rámci svazku

6

Stát vydavatele periodika

GB - Spojené království Velké Británie a Severního Irska

Počet stran výsledku

17

Strana od-do

064001

Kód UT WoS článku

000575399800001

EID výsledku v databázi Scopus

2-s2.0-85087106326