Time-resolved optical and electrical characteristics of capillary underwater discharges

Baerdemaeker, F. De; Šimek, Milan; Schmidt, J.; Leys, Christophe

doi:10.1007/s10582-006-0262-8

Cited by 4 publications

(5 citation statements)

References 9 publications

(8 reference statements)

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“…The OH radical generation is investigated by recording the light emission in the wavelength range 280-400 nm. This part of the discharge spectrum corresponds to the OH radical transition 2) [31,32]. The light intensity I ij due to a transition from the energy state i to energy state j is proportional to the number of radicals in the excited state i, i.e.…”

Section: Kinetics Of Oh Radical Generationmentioning

confidence: 99%

Influence of capillary geometry and applied voltage on hydrogen peroxide and OH radical formation in ac underwater electrical discharges

Nikiforov

Leys

2007

Plasma Sources Sci. Technol.

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The generation of hydroxyl (OH) radicals and hydrogen peroxide (H 2 O 2 ) in underwater capillary discharges with different geometries is studied. It is found that the efficiency of the production of these active species depends on the input power and on the length of the capillary. A maximal rate of H 2 O 2 generation of 3.6 × 10 −3 mmol l s −1 has been measured in a 1 mm capillary at a discharge power level of 77 W. The hydrogen peroxide yield is lower for the 1 mm capillary (h H 2 O 2 = 4.1 g kW −1 h −1 ) than for the 5 mm capillary (h H 2 O 2 = 7.8 g kW −1 h −1 ). The kinetics of OH formation is investigated by recording emission spectra in the UV range (280-400 nm). It is shown that the rate of OH formation sharply decreases with increasing capillary length, for capillaries longer than 3 mm. A comparison of the efficiency of different plasma-solution reactors for the generation of active species has been carried out. In the investigated capillary discharge the hydrogen peroxide yield is higher than the values reported for a diaphragm discharge and for a glow discharge with the electrolyte cathode at atmospheric pressure.

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Section: Kinetics Of Oh Radical Generationmentioning

confidence: 99%

Influence of capillary geometry and applied voltage on hydrogen peroxide and OH radical formation in ac underwater electrical discharges

Nikiforov

Leys

2007

Plasma Sources Sci. Technol.

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“…In these so-called underwater electrodeless discharge schemes plasma is generated in one or more holes in a dielectric separating two water vessels. In capillary discharges, the length-to-diameter ratio of the holes is 1 [22][23][24][25][26], whereas it is of the order of 0.1-1 in diaphragm discharges [27][28][29][30][31][32]. Diaphragm discharges have been studied in view of applications such as water 0963-0252/07/020341+14$30.00 © 2007 IOP Publishing Ltd Printed in the UK Figure 1.…”

Section: Introductionmentioning

confidence: 99%

“…decontamination [31,33,34], chemical synthesis [15,35,36] and shock wave generation [37]. On capillary underwater discharges, however, only very few reports can be found [22][23][24][25][26]. Recent research by the authors showed that periodic plasma generation in an asymmetrical capillary induces a flow of liquid between the two vessels, which might be utilized to design a micropump [24].…”

Section: Introductionmentioning

confidence: 99%

Characteristics of ac capillary discharge produced in electrically conductive water solution

Baerdemaeker

Šimek

Schmidt

et al. 2007

Plasma Sources Sci. Technol.

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Basic electrical, optical and calorimetric characteristics of an ac (50 Hz) driven capillary discharge produced in a water solution were studied for initial water solution conductivity in the range 50-1000 µS cm −1 . Typical current and voltage waveforms and emission intensities produced by several electronically excited species were recorded with high time resolution. The evolution of the electrical current, power and capillary resistance was inspected during positive ac half-cycle for various operational regimes. A fast relaxation of the discharge following a breakdown event was observed. Optical measurements indicate that radiative species are mostly generated during the first few hundreds of nanoseconds of plasma generation and that the average duration of plasma emission induced by a discharge pulse is of the order of a few microseconds. Results of calorimetric measurements are in good agreement with average electrical measurements and support the assumption that the discharge is a constant source of heat delivered to the liquid. Assuming that only a fraction of the heat released inside the capillary can be transported by conduction through the capillary wall and via its orifices, the processes of bubble formation, expulsion and re-filling the capillary with 'fresh' water must play a key role in maintaining a thermal balance during long-time steady-state operation of the device. Furthermore, a simplified numerical model and a first order energy deposition calculation prove the plausibility of the bubble breakdown mechanism.

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“…In these so-called underwater 'electrodeless' schemes, plasma is formed inside one or more holes in a dielectric separating two water vessels. In a capillary discharge, the length-to-diameter ratio of the hole(s) is 1 [22][23][24][25][26], whereas it is of the order of 0.1-1 in a diaphragm discharge [27][28][29][30][31][32]. Underwater electrodeless discharges have been studied in connection with water decontamination [31,33,34], chemical synthesis [15,35,36] and shock wave generation [37].…”

Section: Introductionmentioning

confidence: 99%

Efficiency of hydrogen peroxide production by ac capillary discharge in water solution

Baerdemaeker

Šimek

Leys

2007

J. Phys. D: Appl. Phys.

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Efficiency of hydrogen peroxide production by an ac driven underwater capillary discharge was investigated quantitatively. The concentration of formed hydrogen peroxide was measured by a colorimetric method using a specific reaction between H2O2 and a titanium reagent. The amount of formed H2O2 increases linearly during the first hour of the discharge duration. The initial rate and corresponding total energy yield of H2O2 formation by the capillary discharge were determined for initial electrical conductivity of aqueous solution in the range of 100–500 µS cm−1 and average applied power in the range 30–90 W. It comes out that the total energy yield of H2O2 formation, derived from the initial rate of H2O2 formation and the average applied power, increases linearly with average applied power and that solution conductivity has only a negligible effect on the energy yield. A maximum total energy yield of H2O2 formation of 0.9 g kWh−1 was obtained for a 500 µS cm−1 aqueous solution.

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Time-resolved optical and electrical characteristics of capillary underwater discharges

Cited by 4 publications

References 9 publications

Influence of capillary geometry and applied voltage on hydrogen peroxide and OH radical formation in ac underwater electrical discharges

Influence of capillary geometry and applied voltage on hydrogen peroxide and OH radical formation in ac underwater electrical discharges

Characteristics of ac capillary discharge produced in electrically conductive water solution

Efficiency of hydrogen peroxide production by ac capillary discharge in water solution

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