Charge neutralization of submicron aerosols using surface-discharge microplasma

Kwon, Soon−Bark; Seto, Takafumi; Kim, Y.J.

doi:10.1016/j.jaerosci.2005.05.007

Cited by 37 publications

(22 citation statements)

References 28 publications

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“…(a) Schematic of the surface discharging unit consisting of discharge electrode and ground electrode on both sides of a mica sheet, (b) the surface discharger (SD) with its electrical configuration, and (c) a sketch of positive and negative dc pulses supplied by the power source. acquired neutral fraction showing good agreement with the bipolar diffusion charging theory and with results obtained by an 241 Am source (Kwon et al 2005). In the present study, we used two dielectric barrier sheets for each electrode (a single mica sheet was shared by positive and negative electrodes in the previous study) and the use of separate sheets of mica was found to enhance the controllability of the bipolar ion concentration ratio probably due to the reduced interference between positive and negative discharges.…”

Section: Methodssupporting

confidence: 80%

“…A positive (or negative) dc pulse biased by the positive offset voltage, V po , (or negative offset voltage, V no ,) was supplied as described in Figure 1(c). Detailed information on the dielectric barrier discharge using this system can be found elsewhere (Kwon et al 2005). the SMAC chamber used in this study.…”

Section: Methodsmentioning

confidence: 99%

“…The aim of the present study was to determine the charge distribution obtained using the SMAC, which was qualitatively presented in our previous study (Kwon et al 2005) and to investigate the effect of unequal bipolar ion concentration on the charge distribution. For this purpose, we performed quantitative analysis of the charge distribution of monodisperse particles in the size range of 30-200 nm acquired by the SMAC and compared the results with calculated charge fractions obtained from an analytical solution based on the diffusion charging theory.…”

Section: Introductionmentioning

confidence: 98%

“…In our previous study, we found that the surface-discharge on a dielectric barrier induced by dc pulses could be utilized as a stable bipolar ion source with high concentration for neutralizing submicron aerosol particles successfully (surface-discharge microplasma aerosol charger: SMAC; Kwon et al 2005). Moreover, such a source could control separately the concentrations of positive and negative ions, which could change the particle charge distribution significantly.…”

Section: Introductionmentioning

confidence: 99%

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Characteristics of Aerosol Charge Distribution by Surface-Discharge Microplasma Aerosol Charger (SMAC)

Kwon

Fujimoto

Kuga

et al. 2005

Aerosol Science and Technology

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The surface discharge on a dielectric barrier induced by dc pulses was successfully utilized as a stable bipolar ion source for neutralizing submicron aerosol particles where the concentration of positive and negative ions could be adjusted independently (a surface-discharge microplasma aerosol charger: SMAC; Kwon et al., 2005). The aim of this study was to determine the charge distribution obtained by the SMAC, which has been qualitatively presented in our previous study, and to investigate the effect of unequal bipolar ion concentration on the charge distribution. For this purpose, we performed quantitative analysis of the charge distribution of monodisperse particles in the size range of 30-200 nm acquired by the SMAC and compared the charge distributions with calculated charge fractions obtained from the diffusion charging theory. The ion parameters were calculated by measuring the ion mobility of positive and negative ions and they were used to obtain the analytic solutions of charge distribution. The charge distributions obtained by the equal or unequal concentration of bipolar ions adjusted by the SMAC showed general agreement with the diffusion charging theory.

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Section: Methodssupporting

confidence: 80%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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Characteristics of Aerosol Charge Distribution by Surface-Discharge Microplasma Aerosol Charger (SMAC)

Kwon

Fujimoto

Kuga

et al. 2005

Aerosol Science and Technology

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“…The most widespread method of producing such bipolar ion atmosphere is through the use of a weak radioactive source (typically 85 Kr, 241 Am or 210 Po, with the first one emitting b radiation while the last two a radiation). However, limitations posed by handling radioactive materials triggered a substantial amount of research work on alternative bipolar charging methods, including bipolar corona neutralizers (Romay et al 1994;Stommel & Riebel 2004;Han et al 2009;Kallinger et al 2012), dielectric barrier discharging (Kwon et al 2006) and soft X-rays (Shimada et al 2002;Yun et al 2009;Kallinger, et al 2012;Jiang et al 2014).…”

Section: Introductionmentioning

confidence: 99%

Methodology to quantify the ratio of multiple-to single-charged fractions acquired in aerosol neutralizers

Mamakos

2016

Aerosol Science and Technology

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A methodology for the quantification of the ratio of multiple-to single-charged fractions acquired in aerosol neutralizers is presented. These quantities are necessary for an accurate monodisperse calibration of aerosol instrumentation. A tandem Differential Mobility Analyzer (DMA) setup is required, with the second DMA scanning the electrical mobility spectra classified in the first DMA. In contrast to previous studies on the quantification of bipolar charge distribution utilizing tandem DMA schemes, the methodology targets at the direct determination of the multiple-to singlecharge fractions and does so through the analysis of the raw signal instead of the inverted size distributions, thus circumventing errors associated with the assumptions in the DMA data inversion. The proposed methodology is employed for the characterization of different types of aerosols commonly employed for instrument calibration. Spherical liquid particles (emery oil and dioctyl sebacate) were found to acquire lower multiple charge fractions than those suggested by the commonly employed regression fits of Wiedensohler, which was published in the year 1988 in the Journal of Aerosol Science (vol. 19,, but still within the range of values reported in the literature. Diffusion flame soot and spark generated graphite particles, produced by a miniCAST 6203C burner and a PALAS DNP 3000, respectively, exhibited higher fraction of multiple charges, in good agreement with previous work on agglomerates. The use of a soft X-ray bipolar charger (TSI 3088) yielded systematically higher multiple fractions of positive charges compared to a 85 Kr neutralizer (TSI 3077A), confirming the importance of direct photoionization charging on the former.

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Reversible Aggregation and Dispersion of Particles at a Liquid–Liquid Interface Using Space Charge Injection

Jia

Huang

Lan

et al. 2019

Adv Materials Inter

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large interparticle spacing, akin to Wigner crystals, under the combined effect of the attractive and repulsive interparticle interactions. These forces are long-ranged compared to corresponding interactions in bulk media. The attractive interaction between interfacial particles are believed to originate from interface undulation around individual particles due to nanoscale surface roughness and heterogeneity, [14,15] whereas the long-ranged repulsion arises from the asymmetric surface charge distribution across the interface. [16][17][18] Changes in the structure of particle monolayers at liquid-liquid interfaces can be achieved by tailoring the interparticle interactions with different external stimuli. One well-established method for inducing aggregation of initially hexagonal monolayers, for example, is to add electrolytes and/or surfactants to the subphase, which decreases the magnitude of the repulsive interactions. [19,20] Also, changing particle wettability at the interface can affect the order-disorder transition of interfacial silica particles. [21,22] In addition, electric fields can also tune the interfacial structures by exerting a lateral electric force and a lateral capillary force resulting from a vertical electrical force. [23][24][25] External ions or ultraviolet light can also transform the structure of particle monolayers to fractal aggregates or mesostructures. [26] Despite these strategies, the transitions are typically unidirectional without reversibility, limiting their practical applications. Although a scheme has achieved reversible order-disorder transitions at soft (i.e., oil-gel) interfaces by altering the attractive interaction through addition or removal of the oil phase, [27] this method requires the addition of a gelling agent in the aqueous phase and also lacks tunability by relying on oil evaporation. Therefore, a strategy to induce reversible assembly of colloidal monolayers at a liquid-liquid interface without changing the chemical nature of the two phases would significantly advance our understanding of particle-laden fluid interface phenomena and facilitate the use of these interfacial monolayers in fundamental investigations.In this work, reversible aggregation-dispersion transition of interfacial colloid monolayers is induced by injecting space charge from a corona discharge, inspired by the principles of surface charge neutralization, [28,29] and electrostatic precipitation. [30] We show that an ordered colloidal monolayer of charged particles at an oil-water interface can be induced to Colloids at water-oil interfaces can form ordered monolayers when surface charge-induced repulsion overcomes capillary attraction. Such particle monolayers play an important role in the stabilization of emulsions and also can serve as an exquisite model system to study fundamental physical phenomena. However, it is challenging to dynamically control the relative magnitudes of repulsion and attraction between the particles, especially with reversibility, to induce reversible aggregation and...

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Charge neutralization of submicron aerosols using surface-discharge microplasma

Cited by 37 publications

References 28 publications

Characteristics of Aerosol Charge Distribution by Surface-Discharge Microplasma Aerosol Charger (SMAC)

Characteristics of Aerosol Charge Distribution by Surface-Discharge Microplasma Aerosol Charger (SMAC)

Methodology to quantify the ratio of multiple-to single-charged fractions acquired in aerosol neutralizers

Reversible Aggregation and Dispersion of Particles at a Liquid–Liquid Interface Using Space Charge Injection

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