Modeling of Spherical Dust Particle Charging due to Ion Attachment

The attachment of positive and negative ions to settling spherical dust particles is studied. A novel 1D numerical model has been developed to parameterize the charging process in the presence of a large-scale electric field. The model is able to self-consistently calculate the modification of atmospheric ion densities in the presence of the dust particles, and the consequent alteration of the atmospheric electrical conductivity and the large-scale electric field. Moreover, the model estimates the acquired electrical charge on the dust particles and calculates the electrical force that is applied on them. Using observed dust size distributions, we find that the particles can acquire electrical charge in the range of 1–1,000 elementary charges depending on their size and number density. The particles become mainly negatively charged, but under specific conditions giant mode particles (larger than 50 μm radius) can be positive. Moreover, the large-scale electric field can increase up to 20 times as much as the fair weather value. However, our approach shows that the resultant electrical force is not enough to significantly influence their gravitational settling, as the ratio between the electrical force magnitude and the gravity magnitude does not exceed the value of 0.01. This indicates that the process of ion attachment alone is not sufficient to create strong electrical effects for the modification of particle dynamics. Therefore, other processes, such as the triboelectric effect and updrafts, must be included in the model to fully represent the impact of electricity on particle dynamics.

Bimetallic sulfide based on various carbon materials for supercapacitors

The NiCo2S4/C hybrid material was successfully prepared by a simple one-step hydrothermal method. Carbon composite increases the specific surface area of the material and provides more ion attachment points during the electrochemical process. Conducive to the ion transportation and transfer, the composition of carbon material greatly improves the conductivity of the hybrid material. Electric double-layer capacitor materials can accept transferred ions faster than pseudocapacitor materials, enable the hybrid materials better adapt to intensity current changes. Compared with a single carbon material or a pseudocapacitance material, it has a higher specific capacity. This discovery is of great significance to the research of pseudocapacitive materials and supercapacitors.

A 3D Time-Dependent Model for the Study of the Electrification of Non Spherical Dust Particles due to Ion Attachment

<p>Electrical processes can be a potential key player in the lifecycle of desert dust. The dust particles can be charged during their transport, either by the attachment of atmospheric ions or by particle to particle collisions (triboelectric effect). Measurements indicate that, on average, larger particles become positively charged while the smaller ones become negatively charged [<em>Zhao, H. L.</em>, J. Electrostat, 55, 2002; <em>Lacks, D.J.</em>, et al., Phys. Rev. Lett., 100, 188305, 2008; <em>Merrison, J.P.</em>, Aeolian Res., 4, 2012; <em>Shinbrot, T. and Herrmann, H.J.</em>, Nature, 451, 2008]. During dust transportation, the larger and mainly positively charged particles separate from the smaller negatively charged particles due to the gravitational sedimentation, which sorts the dust particles by size. This process develops vertical electric fields within the dust cloud, enhancing the pre-existing field due to the depletion of atmospheric conductivity by the presence of the dust layer [<em>Gringel W. and Mulheisen. R.</em>, Beitr. Phys. Atmos., 51, 121–8, 1978]. Depending on its strength, the total electric field within the dust cloud can: (a) counteract the gravitational settling of large particles and (b) cause a preferential orientation of the non-spherical particles along the vertical direction affecting particle aerodynamics [<em>Ulanowski, Z., et al.</em>, Atmos. Chem. Phys., 7, 2007]. Therefore, electrical processes may alter dust removal processes, and thus the evolution of particle size during transport, affecting dust-radiation-cloud interactions and the associated air quality [<em>Sajani S.Z., et al.</em>, Occup. Environ. Med., 68(6), 2011], weather, and climate modeling [<em>Mahowald, N., et al.</em>, Aeolian Res., 15, 2014].</p><p>In the present work, we have developed a novel 3D Cartesian time-dependent model that takes into account several atmospheric processes, such as: (i) the ionization due to the galactic cosmic rays radiation, (ii) the ion-ion recombination, and (iii) the ion attachment to non spherical dust particles.  The model is able to self-consistently calculate the time dynamics of the atmospheric conductivity, and the atmospheric electric field, under the presence of a distribution of stationary non spherical dust particles. Additionally, the total charge density, dust particle charge and dust particle orientation are also quantified. The new 3D electrification formalism allows the study of dust layers without imposing any symmetry and  is valid for layers with any horizontal and vertical extend, as opposed to 1D models which are valid when the horizontal extend is much larger than the vertical, or to 2D models which assume a symmetry in the shape of the dust layer. The results are compared, in the limiting case that the horizontal extend is much larger than the vertical one, with those obtained from 1D models found in the past literature [e.g. <em>Zhou, L., Tinsley, B.A.</em>, Adv. Space Res. 50, 2012]. Moreover, the effect of the studied electrification process is assessed through a comparison with recent and unique electric field measurements within lofted dust layers, as performed with the use of novel low cost atmospheric electricity sensors in an experimental campaign of the D-TECT ERC project, in Cyprus the past November.</p>

Real-time monitoring for reforming processes of liquid hydrocarbon fuel–air pre-mixtures by non-thermal plasmas using ion attachment mass spectrometry

Plasma induced reforming processes of fuel–air mixtures were investigated to understand the mechanism of the low temperature plasma-assisted combustion technique, which can improve the thermal efficiency and stability of internal combustion engines.

Development of lithium attachment mass spectrometry – knudsen effusion and chemical ionisation mass spectrometry (KEMS, CIMS)

Development of lithium ion attachment for the measurement of atmospherically relevant species in Chemical Ionisation and Knudsen Effusion Mass Spectrometry.

Trapping chlorine radicals via substituting nitro radicals in the gas phase

Chlorine radicals (Cl˙), generated by the YAG laser photolysis (λ = 355 nm) of Cl2 in the gas phase, were captured by using 2,2-diphenyl-1-picrylhydrazyl (DPPH˙) and were characterized using ion attachment ionization-quadrupole mass spectrometry.