Underwater streamer discharges have various potential applications in the fields of wastewater treatment, crop seed processing, etc. The underwater discharge types an important effect on practical applications. In this work, microsecond pulsed are investigated by using ultra-high-speed frame camera system at different water conductivities and applied voltages. It is found that there exist two under same experimental conditions: fan-shaped bush type long-single filament type. conductivity 800...

Abstract Gas-liquid discharge is considered to be one of the most promising technologies for nitrogen fixation because its ability generate high concentrations reactive species in gas-liquid phase. Increasing contact area between plasma and liquid an effective method improve mass transfer efficiency. In this study, a nanosecond pulse was employed drive coplanar plate-like electrode achieve large surface about 70*30 mm2, effects voltage, frequency, conductivity temperature on...

Abstract Gas temperature is an essential parameter in terms of thermodynamics and kinetics a plasma chemical reaction, but the gas dielectric barrier discharge (DBD) difficult to be measured often misunderstood as near room temperature. In this work, axial distributions center (Tc) wall (Tw) temperatures bare, water-cooled, heat-insulated furnace-heated DBD reactors are measured. It found that Tc significantly higher than Tw hasasymmetric bow-likeprofile distribution, which indicates radial...

The propagation behavior of microsecond pulsed positive streamer discharge in low-conductivity water was investigated via photography and shadowgraph imaging. Eight successive images were acquired from a single pulse, allowing for the study overall behavior; both emission shadow emission-combined obtained. experimental results confirmed that at later stage is weak illuminance has velocity ∼2 km/s, which slower than secondary (∼30 km/s) but as fast primary one (∼2 km/s). filaments propagated...

An atmospheric-pressure plasma jet generated by a sinusoidal power input of tens kilohertz and designed with concentric wire-mesh cylinder electrode is characterized in this paper. Effects gas flow rate on the length have been investigated, seen to three different modes varied flow. The temperature measured fine-structure fitting emission bands UV OH, molecules, Boltzmann plot method, comparison data obtained an optical-fiber thermometer. In addition, electron density generation region...

The temporal evolution of the pulsed positive streamer discharge in water is investigated by high-speed photography. Four successive one-shot photographs were acquired from same pulse. Two modes propagation, called first mode and second mode, confirmed time-resolved images. first-mode appears as an expanding luminous plasma ball, no filament can be recognized at this stage. standing time maximum radius ball are 40-60 ns 600-800 μm, respectively. Then, transits to which many filaments grow up...

The prevention of plasticizer leaching from the inner surface a narrow polyvinyl chloride (PVC) tube by dc glow discharge plasma generated inside was investigated. PVC tubes with 4-mm diameter treated Ar plasma. amount leached measured using novel extraction device. effects treatment time, working pressure, and applied voltage on were All plasma-treated samples showed strong reduction respect to untreated one. reduced factor three after 30-min at 40 Pa 700 V. It found that had little effect...

The underwater streamer discharge has received extensive attention in the field of environmental protection, because it can generate free radicals and reactive oxygen species directly water. multi-needle electrode is a basic configuration for achieving large-volume discharge. Understanding characteristics important designing reactors. In this work, that assemble 21 needles employed. number anode generating during single pulsed differences morphological between inside edge array are...

Abstract Ammonia (NH3) is decomposed in the afterglow of an atmospheric pressure-nitrogen microwave plasma torch (MPT) for hydrogen production. And optical emission spectroscopy (OES) employed diagnosis to analyze characteristic molecular bands and determine rotational temperature using Boltzmann plot method. The mechanism chemical joule heating NH3decomposition discussed by studying concentration excited species with respect power NH3 flow rate. Additionally, gas field distributed reaction...

In an underwater streamer discharge, plasma channels are created and propagate in water. After the ionized gas gradually cool down decay. this paper, a time-resolved study on decay process of induced by pulsed positive discharge water is performed using high-speed camera system. The have many branches. Some them grow from tip point anode, forming main From branch, some subbranches develop. subbranch dilapidates rapidly into microbubbles, while branch abbreviates toward root branch. A bubble...

Two new clerodane-type diterpenoids were isolated from the roots of Croton crassifolius Geisel. The structures these compounds elucidated as 9-[2-(2(5H)-furanone-4-yl)ethyl]-4,8,9-trimethyl-1,2,3,4,5,6,7,8-octahydronaphthalene-4-carboxylic acid (1) and methyl ester (2) by spectroscopic methods.

The underwater electrical discharges have received extensive attention in water or wastewater treatment. It is important to generate a large-volume corona discharge at relatively low voltage for its practical applications and A coaxial rod-cylinder electrode configuration has been developed generating water. characteristics of the were investigated. temporal evolution images streamer propagation observed by an ultrahigh-speed frame camera system. effect conductivity on was studied. results...

By combining a high-speed frame camera with monochromator, the spatially resolved optical emission spectrum of hydrogen α line in single filament pulsed positive streamer discharge water has been experimentally measured. The electron densities conductivity 200 μS/cm were investigated. During experiment, average energy per pulse was 90.6 ± 13.6 mJ. results show that density is 1017–18/cm3, and present decreasing tendency along axial direction increasing distance from tip anode.

Using the shadowgraph technique, we performed direct measurements of vapor density in discharge channel a pulsed positive streamer water. With this experimental quantitatively measured water conductivity 100 μS/cm. The results show that ranges from to 660 kg/m3, and presents an increasing tendency along axial direction with distance tip anode.

The underwater streamer discharges have a variety of potential applications in environmental science and technology. electrical characteristics the plasma filament generated by play an important role its propagation through water influence production chemical reactive species energy injected into filament. In this paper, we studied electric field inside filament, at head conductivity By measuring maximum length radius found that linear relation between applied voltage is not affected within...

The residual gaseous filament soon after a streamer discharge in water contains wealth of information closely related to the propagation. We have investigated microsecond pulsed positive by using shadowgraph imaging technique. Based on obtained shadow images, we measured average gas density, radius, and length filament. found that density has no significant dependence applied voltage, but decreases from 883 610 kg/m3 as conductivity increases 20 476 μS/cm. amount produced unit energy...

We performed experimental observations to distinguish an individual shock front released by a pulsed positive streamer discharge in water. The step length between two adjacent wave events was measured and its dependence on water conductivity applied voltage investigated. found that the is ∼160 μm, independent of both voltage, within range studied. Based bubble theory electrical liquid, we concluded breakdown gaseous micro-segment near head filament After launching wave, pauses waits for...

The temporally and spatially resolved optical emission spectrum of Hα a pulsed spark discharge in water was experimentally measured. electron densities, along the radial direction filament, for with conductivity 100 μS/cm were investigated. density filament found to be 1018/cm3 order magnitude. highest measured at primary stage it decreased time. distribution increased from center edge filament.

Six compounds were isolated from the secondary metabolites of jellyfish-derived fungus Aspergillus fumigates, whose structures identified by chemical methods and spectroscopic analysis as pseurotin F1 (1), azaspirofurans B (2), (22 E, 24 R)-24-methyl-5α-cholesta-7,22-diene-3β,5,6β-triol (3), 5α,8α-epidioxyergosta-6,22-dien-3β-o1 (4), cyclo-(L-Pro-L-Tyr) (5), fumitremorgin C (6). The 1–5 fumigates for first time. (1–6) evaluated antibiotic activity cytotoxicity against six bacterial strains...