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John P W Stark - One of the best experts on this subject based on the ideXlab platform.
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the influence of geometry on the flow rate sensitivity to Applied Voltage within cone jet mode electrospray
Journal of Applied Physics, 2012Co-Authors: Charles Ryan, Katherine L Smith, John P W StarkAbstract:This work investigates in greater detail than in previous studies the effect of geometry on the relationship between emitted flow rate and Applied potential difference in cone-jet mode electrospray systems. The magnitude of the flow rate to Voltage relationship is demonstrated to be sensitive to numerous geometric parameters. An explanation of this variation is offered; it is demonstrated that in the cone-jet mode of operation the change of flow rate with the Applied extraction Voltage is due to the change in electric field at the tip of the emitter. By a finite element method simulation of the assumed electrostatic process the analysis is further extended to include all geometric parameters. The results outlined show the change of flow rate with Applied Voltage in cone-jet mode electrospray can be significant. This dependence will, under some conditions, have a considerable effect on the electrospray flow rate, and consequently current and droplet size. This has implications on electrospray applications involving the use of the Applied Voltage to extract the sprayed solution, including nano-electrospray mass spectrometry techniques and some forms of electrospinning.
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the sensitivity of volumetric flow rate to Applied Voltage in cone jet mode electrospray and the influence of solution properties and emitter geometry
Physics of Fluids, 2006Co-Authors: Katharine Smith, Matthew S Alexander, John P W StarkAbstract:A high accuracy online flow rate measurement system has been used to demonstrate the effect of Applied Voltage, Vapp, on the volumetric flow rate, Q, through an electrospray system. Several solutions of the organic solvents ethylene and triethylene glycols doped with sodium iodide to give varying conductivities in the range of 0.0025–0.23S∕m have been sprayed. It was established for the first time that solution conductivity has no appreciable effect on the sensitivity of flow rate to Applied Voltage in the cone-jet mode of electrospray. However, it appears that even when the hydraulic resistance is taken into account, the sensitivity of flow rate as controlled by the Applied Voltage is additionally related to the emitter exit geometry. These findings are of particular importance to both spacecraft propulsion and electrospray mass spectrometry technologies and suggest careful emitter geometry design considerations will lead to greater control over electrospray properties.
G V Naidis - One of the best experts on this subject based on the ideXlab platform.
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simulation of subnanosecond streamers in atmospheric pressure air effects of polarity of Applied Voltage pulse
Physics of Plasmas, 2016Co-Authors: Yu N Babaeva, G V NaidisAbstract:Results of simulation of subnanosecond streamer propagation in corona gap configuration, obtained in the framework of 2D fluid model, are presented. Effects related with the polarity of a Voltage pulse Applied to the stressed electrode are discussed. It is argued that these effects (dependence of the discharge current and propagation velocity on the polarity of Applied Voltage) observed in experiments can be attributed to the difference in initial (preceding the streamer formation) distributions of charged species inside the gap. This difference can be caused by preionization (at negative polarity) of the gas inside the discharge gap by runaway electrons. Calculated streamers have large widths (up to 1 cm) and move with velocities in the range of 109–1010 cm s−1, similar to experimental data.
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modeling of streamer dynamics in atmospheric pressure air influence of rise time of Applied Voltage pulse on streamer parameters
IEEE Transactions on Plasma Science, 2016Co-Authors: Natalia Yu Babaeva, G V NaidisAbstract:Results of simulation of positive streamer propagation in atmospheric air, obtained in the framework of a 2-D fluid model, at various rise times of Applied Voltage pulses are presented. It is shown that the variation of the rise time allows one to control the streamer characteristics: the streamer widths, propagation velocity, densities of charged and excited neutral species, and electric current. At very short (subnanosecond) rise times, it is possible to obtain wide streamers, carrying large currents and producing considerable amounts of reactive species.
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modeling of helium plasma jets emerged into ambient air influence of Applied Voltage jet radius and helium flow velocity on plasma jet characteristics
Journal of Applied Physics, 2012Co-Authors: G V NaidisAbstract:Simulation of guided positive streamers propagating along helium jets emerged into ambient air is performed, in the framework of a standard two-dimensional streamer model, for various values of parameters (Applied Voltage, helium flow velocity, and jet radius) governing the streamer dynamics and structure. Obtained dependencies of the streamer velocity, radius, and propagation length on the governing parameters are compared with available results of observations.
Wenjiang Ding - One of the best experts on this subject based on the ideXlab platform.
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preparation of mg nd zn zr alloys semisolid slurry by electromagnetic stirring
Materials & Design, 2016Co-Authors: Yushi Chen, Liang Zhang, Wencai Liu, Wenjiang DingAbstract:Abstract The effects of electromagnetic stirring (EMS) including stirring time, Applied Voltage and rotational frequency on the microstructure of semisolid slurries of the Mg–Nd–Zn–(Zr) alloys were investigated. The results indicate that all of the parameters have large effects on the microstructure of the slurries. After being treated by EMS, the morphology of primary α-Mg phases in the Mg–3Nd–0.2Zn (NZ30) alloy slurries evolves from dendrite to three types: rosette, dendrite, and spheroid, while a semisolid microstructure with small and spheroidal particles is obtained in the Mg–3Nd–0.2Zn–0.4Zr (NZ30K) alloy slurries. The data for solid fraction with stirring time can be fitted to linear equations. The increase of Applied Voltage and rotational frequency makes the primary α-Mg phases initially refined and then coarsened. The optimal processing parameters are stirring time 120–180 s, Applied Voltage 300–350 V, rotational frequency ~ 20 Hz for NZ30 alloy, and stirring time 30–180 s, Applied Voltage ~ 350 V, rotational frequency ~ 20 Hz for NZ30K alloy. The average particle size of NZ30 alloy can be refined from ~ 879 to ~ 457 μm. Furthermore, the effects of Applied Voltage and rotational frequency on undercooling and melt temperature were also discussed on the basis of thermodynamic theory.
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preparation of an mg gd zn alloy semisolid slurry by low frequency electro magnetic stirring
Materials & Design, 2015Co-Authors: Cunlong Wang, Antao Chen, Liang Zhang, Wencai Liu, Wenjiang DingAbstract:Abstract The effects of low frequency electromagnetic stirring (LFEMS) including Applied Voltage, rotational frequency and cooling rate on the microstructure of semisolid slurry of the Mg–2.5Gd–1Zn (at.%) alloy have been investigated. The Applied Voltage, rotational frequency and cooling rate all have a remarkable influence on the microstructures of the slurries. The LFEMS treatment leads to the morphology of primary Mg particles evolved from dendritic to non-dendritic. The increase of Applied Voltage leads to refined primary Mg particles, while the increase in rotational frequency makes the α-Mg particles initially refined and then coarsened. The decrease of cooling rate also leads to refinement of primary Mg particles. The optimal processing parameters for the fabrication of semisolid slurry are found to be: Applied Voltage 300–350 V, rotational frequency 15–20 Hz and cooling rate below 1.4 K/min. Under the optimized parameters, fine and spherical primary Mg particles were obtained, and the average particle size is refined from ~ 680 to ~ 150 μm.
Toshio Suzuki - One of the best experts on this subject based on the ideXlab platform.
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accelerated formation of sodium depletion layer on soda lime glass surface by corona discharge treatment in hydrogen atmosphere
Applied Surface Science, 2014Co-Authors: Keiga Kawaguchi, Shiro Funatsu, Keiichiro Uraji, Kiyoshi Yamamoto, Toshio Suzuki, H. Ikeda, Daisuke Sakai, Kenji Harada, Junji NishiiAbstract:Formation of a sodium depletion layer on a soda lime glass surface was accelerated efficiently using a corona discharge treatment in H2 atmosphere. One origin of such acceleration was the preferential generation of H+ with a larger mobility at an anode needle end with a lower Applied Voltage than that in air. The second origin was the Applied Voltage across the glass plate during the corona discharge treatment, which was estimated theoretically as 2.7 times higher than that in air. These two effects doubled the depletion layer thickness compared with that in air.
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phase field modeling for electrodeposition process
Science and Technology of Advanced Materials, 2007Co-Authors: Yasushi Shibuta, Yoshinao Okajima, Toshio SuzukiAbstract:A novel phase-field model for electrochemical processes, in which cations were driven by an electrostatic potential coupled with a thermodynamic potential, was formulated from a variation of the Ginzburg–Landau free-energy functional. Using this model, an electrodeposition process of copper deposits from copper-sulfate solution was studied using a phase-field simulation. The dependence of the growth velocity of the electrode on the Applied Voltage was examined in a one-dimensional system. Then, the morphological transition of the electrodeposits as functions of the Applied Voltage and the composition ratio of copper ion in electrolyte was examined using a two-dimensional system. Thin and dense branches were observed at a low Applied Voltage. The shape of the branches became more complicated as the composition ratio was lowered.
Charles Ryan - One of the best experts on this subject based on the ideXlab platform.
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the influence of geometry on the flow rate sensitivity to Applied Voltage within cone jet mode electrospray
Journal of Applied Physics, 2012Co-Authors: Charles Ryan, Katherine L Smith, John P W StarkAbstract:This work investigates in greater detail than in previous studies the effect of geometry on the relationship between emitted flow rate and Applied potential difference in cone-jet mode electrospray systems. The magnitude of the flow rate to Voltage relationship is demonstrated to be sensitive to numerous geometric parameters. An explanation of this variation is offered; it is demonstrated that in the cone-jet mode of operation the change of flow rate with the Applied extraction Voltage is due to the change in electric field at the tip of the emitter. By a finite element method simulation of the assumed electrostatic process the analysis is further extended to include all geometric parameters. The results outlined show the change of flow rate with Applied Voltage in cone-jet mode electrospray can be significant. This dependence will, under some conditions, have a considerable effect on the electrospray flow rate, and consequently current and droplet size. This has implications on electrospray applications involving the use of the Applied Voltage to extract the sprayed solution, including nano-electrospray mass spectrometry techniques and some forms of electrospinning.