Negative Ion Concentration Research Articles

Generating Negative Air Ions in Construction Waterscapes at a Garden Scale

High concentrations of negative air ions (NAIs) and low concentrations of positive air ions (PAI), along with a low monopole coefficient (PAI/NAI), are likely to provide physiological and psychological benefits to the humans. A water body produces NAIs through the Lenard effect. This concept can be applied in designing garden waterscapes in residential buildings to provide fresh and healthy air for urban residents. In this study, we conducted several experiments to assess the effectiveness of different waterscape designs in producing air ions. The results revealed that increasing waterfall tiers, slopes, impact points, widths, and heights increased the NAI concentrations and reduced the values of monopole coefficients, thus providing health benefits to humans. In particular, increasing waterfall tiers and slopes increased the NAI concentrations most substantially. Moreover, we established a composite waterscape and determined that it produced fewer NAIs along with a less favorable monopole coefficient compared with the data observed at the experimentally adjusted tiers and slopes. Therefore, we suggest that simple waterscapes with multiple waterfall tiers or steep waterfall slopes should be favored over complex waterscapes. Such simple designs can help construct a garden that provides health benefits.

Edge of magnetized electronegative plasma ion source in the presence of collisional adiabatic thermal positive ions

This paper develops a theoretical model for formation of multilayers in the magnetized electronegative plasma at the edge of plasma ion source. The impacts of positive ion temperature and collisions are studied and quantified by obtaining the structure of the plasma sheath. By adding the negative ions into the discharge, the solutions of Poisson’s equation become oscillatory. A finite temperature for the positive ions and also the collisions results in a change in the behavior of such oscillatory solutions. Here, it is assumed that the collision frequency depends on the positive ions velocity and thermal positive ions flow is adiabatic. The spatial distribution of the species density, electric potential, and positive ion velocity is calculated for different values of positive ion temperature and negative ion concentration for two limiting cases where the collision frequency either is constant or depends linearly on velocity. In addition, the influence of the plasma parameters such as negative ion density and temperature and positive ion temperature is investigated on the space charge and positive ion flux as well as parameter space region. It is also shown that the presence of the negative ion into the plasma ion source influences the extracted positive ion flux and increases the positive ions intensity.

The Role of Modified Boltzmann Relation With Electron Inertia on the Evolution of Solitary Waves Derived by Energy Integral Method Along With the Comparative Studies on Soliton Dynamics in Generalized Multi-Component Plasma

The nonlinear solitary waves in multi-component plasmas coexisting with negative ions, relativistic, and nonrelativistic electrons have been investigated under the influence of a modified Boltzmann relation with electron inertia $m_{\text {e}}$ (mass of electrons $\ne 0$ ) by Sagdeev potential and perturbation methods. The supersonic and subsonic compressive solitons are shown to be dependable on higher negative ion concentrations and the direction of wave propagation ( $k_{x} $ ). The condition of characteristic representation of the new Boltzmann relation appears to generate substantially high amplitude rarefactive solitons based on the direction of propagation, negative to positive ion mass ratio $r$ (>1), and high Mach number $M$ . The relativistic effects in non-Boltzmann electrons causing an increase in mass are responsible for the change in the growth of solitons in plasma.

Coagulation of the Ionized Combustion Products in a Dust Flame of Aluminum Particles

The addition-agent effect of atoms of alkali metals (K, Na, Li, and Cs) and halogens (Cl and I) introduced into the combustion zone of a dust flame of aluminum particles on the average size of Al2O3 nanoparticles is studied. A physical model of coagulation of a monodisperse aerosol is proposed. The model takes into account the formation of a complex plasma consisting of positive and negative ions, electrons, neutral gas molecules, and suspended particles of the condensed phase in the combustion zone. The effect of the forces of Coulomb repulsion of unipolarly charged Al2O3 particles as well as their possible attraction by ion wind on the constant of the coagulation rate is also taken into account. It is shown that at low ion concentrations in the plasma, the coagulation rate is determined by the Coulomb repulsion of the particles, and at ion concentrations greater than 1020 m−3 the coagulation rate is determined by the attraction of the particles by the ion wind. The results of calculations of the dependence of the average Al2O3 particle size on the concentration of the additives are in a good quantitative agreement with the experimental data. The combined effect of the additives and the equilibrium products of aluminum oxide (AlO, Al, and Al2O) evaporation on the concentration of positive and negative gas ions, electrons, and Al2O3 particle size in the condensation zone is analyzed. The peculiarities of the influence of the additives of electronegative gases (Cl and I atoms) on the coagulation rate of a thermally ionized aerosol and on the particle size of Al2O3 are considered.

Measurement of ultralow radiation-induced charge densities using picosecond mid-IR laser-induced breakdown

We demonstrate that avalanche ionization breakdown of air with picosecond mid-infrared (mid-IR) laser pulses is an exceptionally sensitive and quantitative probe of extremely low concentrations of charged species. By exponentially increasing the electron density in the vicinity of a single seed atom or molecule to detectable levels, mid-IR electron avalanche is an analogue of single photon detection in photomultiplier tubes and can be useful in a range of applications. We apply the technique to meter-scale standoff detection of a radioactive source, sensitive to extremely low concentrations of radiation-induced negative ions down to ∼103 cm−3, limited only by background. By imaging the location of spatially isolated avalanche breakdown sites, we directly measure these low densities and benchmark the performance of standoff detection diagnostics. We discuss implementation of this radiation detection scheme at ranges of 10–100 m and adapting the avalanche probe to detection of other low-density plasmas.

Characterization and performance analysis of a new stoneware

Guangdong Baojue New material Industry Co., Ltd fired stoneware with local rock and ore as main raw material. The material and properties of stoneware were characterized in this paper. The composition of stoneware was analyzed by inductively coupled plasma emission spectroscopy (ICP-AES) and X-ray fluorescence spectroscopy (XRF). The phase composition and microstructure of stoneware were analyzed by XRD and metallographic microscope. In this paper, the full-emittance, the air negative ion concentration, the content of the toxic component and the chlorine-removing ability were tested, and the soaking test of the Chinese liquor was carried out. The results showed that stoneware was an excellent material for drinking utensils and was beneficial to human health.

Local discontinuous Galerkin method for modeling the nonplanar structures (solitons and shocks) in an electronegative plasma

Using the hydrodynamic equations of cold inertial positive ions with the Maxwellian distribution for light negative ion and electron densities and the Poisson equation, the family of nonplanar (cylindrical and spherical) Korteweg-de Vries (KdV) equations, i.e., the KdV, modified KdV, and extended KdV (EKdV), are obtained for small but finite amplitude ion-acoustic waves. The nonplanar EKdV equation is used to analyze the time-dependent planar and nonplanar soliton and shock structures. It is well-known that the exact solutions of the family of nonplanar KdV equations are not possible. Therefore, a local discontinuous Galerkin (LDG) method is developed for solving the nonplanar EKdV equation numerically. According to this method, the initial and boundary conditions for the solitary and shock waves are accurately identified. The L2 stability of the LDG method is proved for the general nonlinear case. The existence regions for both solitary and shock excitations have been defined precisely depending on the laboratory plasma parameters. Moreover, the effects of the negative-ion temperature ratio and the negative ion concentration on the profiles of the nonlinear structures (solitons and shocks) are examined. The effect of the geometrical divergence on the pulse profile is also reported which indicates that the localized pulses deform as time goes on. Furthermore, it is found that the amplitude of cylindrical structures (solitons and shocks) is larger than that of planar ones but smaller than that of the spherical ones. Moreover, in cylindrical geometry, the nonlinear structures travel slower than in the spherical ones. The implications of our results agree with the experimental observations.

TiO2/graphene oxide and SiO2 nanocomposites based on poplar wood substrate under UV irradiation and negative oxygen ions generation

Indoor air quality is crucial to human health because poor air quality can easily lead to disease. To improve indoor air quality, it is essential to increase the concentration of negative oxygen ions in the air. Consequently, it is necessary to design a material that can generate negative oxygen ions indoors. In this study, a wood-based functional material was developed by anchoring TiO2/graphene oxide (GO) and silica nanoparticles (SiO2) onto wood. The results showed that the TiO2/GO- and SiO2-treated wood greatly enhanced the mechanical properties of the wood and increased the negative oxygen ion production to 1580 ions/cm3 after 60 min of ultraviolet irradiation, which met the standard for fresh air. These treated wood materials could fulfill the pursuit by an individual for a healthy and environmentally friendly life, and represents a highly promising material in the application of indoor decoration materials.

Water-soluble ion components of PM10 during the winter-spring season in a typical polluted city in Northeast China.

From January 1 to April 22, 2014, an online analyzer for monitoring aerosols and gases (MARGA) was used to measure and analyze water-soluble ions in inhalable particulate matter with a diameter less than 10μm (PM10) during winter-spring in Shenyang city, China. The results yielded three main findings. (1) During the entire observation period and in seven pollution episodes, SO42-, NO3-, and NH4+ (SNA) accounted for 84.4-93.1% of the total water-soluble ions (TWSIs). TWSIs accounted for 32% of PM10 mass during the entire observation period, and the contribution of TWSIs in PM10 ranged from 33.4-43.1% in the seven pollution episodes. The contribution of TWSIs components increased during the pollution episodes, but certain differences were observed in different pollution episodes. In terms of ionic equilibrium, the total concentration of negative ions was slightly greater than that of positive ions and the difference was 3.1% of the total ion load on average, indicating that local aerosols are mainly neutral. The water-soluble ions show clear diurnal variation with the high concentration around 09:00 for SO42-, NH4+, and Cl- which is consistent with the high heating grade index. (2) Pollution episodes often occur in Northeast China, especially during the winter period. Due to the low temperature in the winter, the local coal burning for heating is one of the main sources of pollution besides vehicle exhaust and industrial pollution, which is supported by the higher NO3-/SO42- ratio in April than that in January to March. Sometimes, under the prevailing wind directions of W and SSW, the long-distance transport of pollutants from the Beijing-Tianjin-Hebei region and Shandong province superimposed on local pollution leads to the most severe pollution, such as Ep3 and Ep5. (3) SO42- concentration is closely related to ambient water vapor pressure (e*), with increase as e* increased depending on the temperature. NO3- concentration showed a linear relationship of excess NH4+, which suggests homogeneous gas-phase reaction of ammonia and nitric acid is possibly an important pathways of nitrate formation in the haze pollution process in Shenyang City. In addition, our results also suggest the nighttime liquid-phase reaction may cause large increases of nitrate in the haze pollution process.

Review on Research of the Negative Air Ion Concentration Distribution and its Correlation with Meteorological Elements in Mountain Tourist Area

This paper focuses on the research progress of the negative air ion concentration distribution characteristics and its correlation with meteorological elements in mountain tourist areas for recent decades in China. Many researches showed that the distribution of negative air ion in mountain tourist areas has obvious daily and seasonal variations, and its space changes also have regularity. In a day, the NAI concentration will appear alternately with peaks and troughs. The changes of NAI concentration are the summer, autumn high, winter and spring low, the highest in summer, the lowest in winter. In the middle and low altitude areas, NAI concentration is positively correlated with elevation, and negative correlation in high altitude. The concentration of NAI is related to wind speed, air humidity, air temperature, solar radiation, weather conditions, and other meteorological elements. Most research results show that humidity is the most important meteorological factor affecting NAI concentration. The NAI concentration in mountainous scenic spots is significantly positively correlated with relative humidity and rainfall intensity, positively correlated with wind speed and solar radiation, negatively correlated with air temperature. However, due to different sources of monitoring data, observations difference in time, different sample size and other elements, the conclusions on negative air ion concentration distribution characteristics and its correlation with the meteorological factors are not entirely consistent. Negative air ion monitoring equipment should be gradually standardize to ensure the reliability of monitoring data in the future, while we should take advantage of years of continuous observations to carry the study of correlation between negative air ion and meteorological factors, and this will provide a theoretical basis for negative air ion concentration forecasts.

Characterisation of a multijet plasma device by means of mass spectrometric detection and iCCD imaging

Atmospheric pressure plasma jets (APPJs) have been one of the most studied nonthermal discharges in the past decade. Recently, the use of multiple jets in order to cover larger areas has become desirable. However, the interaction between neighboring jets is a common phenomenon that can greatly modify plasma characteristics up to the point of merging several jets into a single one. The present study focus on bringing new insight on this phenomenon, named jet-to-jet coupling, investigating the discharge modes (coupled and uncoupled) of a plasma source composed of an array of seven plasma jets arranged adjacent to one another and driven by a sinusoidal excitation. The experimental results achieved by means of mass spectrometry, show a considerable increase in ion concentrations in the plasma, up to some orders of magnitude in the case of negative ions, as an effect of jet-to-jet coupling. Temporally resolved imaging of the discharge also shows how the evolution and intensity of the discharge are greatly affected by jet-to-jet interaction. Air/helium mole fraction and negative ions concentration are regarded as the main possible parameters affecting the coupling phenomenon. Moreover, experimental results suggest that the presence of remnant conductive channels behind the ionization fronts governs the propagation of the next ionization fronts, independently from the direction of propagation (from the source toward the target or vice versa). Furthermore, a parametrical investigation of the coupled mode discharge showed the presence of a critical value of the imposed voltage for which a drastic change in the electrical characteristics of the discharge is observed.

Factors affecting the properties of highly conductive flexible ultrathin ITO films in confined large area magnetron sputtering in three dimensions

A large area magnetron source with the strongly confined magnetic field from all direction is applied for the deposition of flexible ultrathin ITO (UT-ITO) films of thickness 30 nm at room temperature for their applications as transparent electrodes. The films show a minimum resistivity of ∼5.0 x 10-4 Ωcm and high transmittance >80% at wavelengths of 400-700 nm. Measurements and data reveal that a high plasma density, high energy flux, and a relatively low concentration of negative oxygen ions (NOIs) to the flux of positive ions (PIs) induce lower mechanical stress to the growing films, which enables a lower resistivity and superior crystallinity with the smooth surface. The capability of the magnetron source and the characteristic plasma properties are studied in light of the resulting film properties. The considerably lower resistivity with higher carrier concentration and mobility of the UT-ITO films prepared at a high power density of 3 W/cm2 and a low O2 gas flow can be attributed to the growth of crystallized UT-ITO films, resulting in the combination of the oxygen vacancy and substitution of Sn4+ to In3+ site through the deposition of a high energy flux and a low flux ratio of NOIs to PIs.

Classification of the new particle formation events observed at a tropical site, Pune, India

A total number of 109 new particle formation events identified in the ion-mobility spectra measured with a Neutral Cluster and Air Ion Spectrometer in the mobility range of 3.16–0.00133 cm2 V−1s−1 (Diameter* range 0.36–47.1 nm) at a tropical site at Pune, (18.53 °N, 73.85 °E, 573 m amsl) India from March 08, 2010–December 31, 2012 are classified based on their shape characteristics under four categories. Most of these events occurred in the morning hours of the pre-monsoon season during the hottest months (April and May) of the year. The meteorological conditions and the changes in ion characteristics associated with some typical events are examined. Average ion-mobility spectrum for the event days shows a minimum in the negative big cluster ion (diameter, 0.85–1.6 nm) concentration and two maxima in the positive intermediate (diameter, 1.6–7.4 nm) and large ion (diameter, 7.4–47.1 nm) concentrations as compared to the average spectrum for all days. Analysis of 7-days airmass back trajectories shows that since the only source of big cluster ions is through the growth of small cluster ions (diameter, 0.36–0.85 nm) the growth of small to big cluster ions is faster when the airmass approaches our site from the land. Further, the concentrations of positive intermediate and light large (diameter, 7.4–22 nm) ions is more when the airmass approaches from the Arabian Sea.

Electronegative (3+1)-dimensional modulated excitations in plasmas

A three-dimensional electronegative plasma model is studied. Modulated ion-acoustic waves are investigated via the activation of modulational instability in the Davey-Stewartson equations, with three space variables. The contributions of the modulation angle (θ) and electronegative plasma parameters are discussed to that effect, including some particular cases such as the parallel and transverse modulations. The parametric linear stability analysis that is proposed shows that the growth rate of instability displays opposite regions of instability for parallel and transverse modulations when the negative ion concentration ratio (α) and the electron-to-negative ion temperature ratio (σn) change.

Variations in Negative Air Ion Concentrations Associated with Different Vegetation Types and Influencing Factors in Chongli District

Variations in Negative Air Ion Concentrations Associated with Different Vegetation Types and Influencing Factors in Chongli District

Distribution Characteristics of Air Anions in Beidaihe in Different Ecological Environments

Qinhuangdao is a provincial municipality under the jurisdiction of Hebei Province and a coastal city in China. Beidaihe is a district under the jurisdiction of Qinhuangdao and is a famous seaside scenic area. Alliance Peak, located in Beidaihe seashore scenic West. Jinshan mouth is the peak of the Union Peak, located in the easternmost Beidaihe waterfront. In this paper, we use the observed data of air negative ions in the Beidaihe, Qinhuangdao, Jinshanzui and Lianfeng Mountains for seven years to study the distribution characteristics of negative air ions in different ecological environments through meteorological observation. Research shows that the annual mean of air anion concentration fluctuates less. The annual mean is 1730 ind·cm-3, and the difference between the highest and lowest concentrations is 535 ind·cm-3. The average air anion concentration was the highest in August at 7785 ind·cm-3 and the lowest in January at 365 ind·cm-3. Negative air ions have obvious spatial characteristics, and negative ion concentrations of the sea and forest air are significantly high. The average annual mean of the sea is 3902 ind·cm-3, and that of the forest is 5403 ind·cm-3. The concentration of air anion changes daily, and daytime concentration is significantly lower than nighttime concentration. The highest peak appears at night or in the morning, while the lowest value appears between noon and afternoon. Inter-annual features and concentration of negative air ions, as well as annual rain days, total rainfall, thunderstorm days, and average relative humidity, are negatively related to the annual average temperature and sunshine hours. However, in the average concentration of negative air ions, the average correlation test of meteorological elements was insignificant. The air anion concentration is negatively correlated with the PM2.5 concentration of fine particulate matter. The concentrations of nitrogen dioxide, sulfur dioxide, and carbon monoxide in the fine particulate matter are negatively correlated with the ozone concentration, which is positively correlated with ozone concentration and is tested by significance. Atmospheric discharge (thunderstorm) can produce a considerable amount of air anion. Air negative ions are an important indicator of air quality, which is of great significance to the living environment. The distribution of negative ions in the study space and its influencing factors in order to provide a basis for air quality assessment in the region and provide references for the long-term research on air anion in different urban areas.

贵州大学春季校园空气负离子分布特征及其评价

以贵州大学春季校园主要功能区为研究对象，对不同天气状态下一天中不同时间段进行空气负离子分布特征的研究及空气质量的评价，为学校师生的生活工作学习环境的管理提升提供科学依据。研究表明，空气负离子具有显著的时空分布特征，因时间及空间的不同而存在差异，空气负离子浓度与空气温度呈反比而与空气相对湿度呈正比关系。 With the main functional areas of Guizhou university in spring as the research object, the charac-ters of air negative ions for different times of different weather condition and air quality are stu-died, which could provide a scientific basis for the management of environment in which students and teachers study, work and live. The paper shows that the air negative ions have remarkable space-time distribution features, which is different because of the different time and space. The air negative ions concentration is inversely proportional with the air temperature and is positively associated with air relative humidity.

Simultaneous Removal of Fluorine and Chlorine from Zinc Sulfate Solution in Iron Precipitation Process

During the zinc electrowinning process, fluorine (F) and chlorine (Cl) ions can cause corrosion of the anode plate and difficulty in stripping the zinc cathode sheet. Because of the increasing use of F/Cl in zinc concentrate in industrial production and the stricter requirements of large-size cathode technology (LARCATH), it is very important to remove F and Cl fully from the zinc sulfate solution. In this paper, tests for removing F/Cl in zinc sulfate solution from zinc plant are carried out by the goethite method. The effects of several factors on the removal of Fe, F, and Cl are studied, including the temperature, flow rate of the zinc sulfate solution, pH value, initial iron concentration, and F and Cl concentrations in the zinc sulfate solution. It can be determined from the experimental results that the removal efficiency of F and Cl can reach 26.4 and 38.6%, respectively, under the conditions of 90 °C, pH value 2.75, and flow rate 3.8 mL/min. The removal rate of F ions is mainly related to the amount of lime milk, whereas the pH value has the greatest impact on the removal rate of Cl. The concentration of negative ions on the surface of goethite increases with increasing pH, which is harmful to the absorption of Cl.

Large amplitude ion-acoustic solitons in warm negative ion plasmas with superthermal electrons

Large amplitude ion-acoustic solitons are investigated in a plasma consisting of warm adiabatic positive and negative-ions and hot superthermal electrons having kappa distributions. Using Pseudo-potential method an energy integral equation is derived for the system. The latter is analysed to examine the existence regions of the solitary waves. It is found that negative ion concentration (α), spectral index (k) and ionic temperature ratio (σ1 or σ2) significantly influence the characteristic of the solitons. Our numerical analysis shows that the system also supports rarefactive solitons for some selected set of plasma parameters. It is also found that large amplitude ion-acoustic compressive and rarefactive solitons exist simultaneously for the same values of plasma parameters. Further an increase in the superthermality (i.e. decreasing the value of spectral index k) leads to shrinking the existing domain of the large amplitude ion-acoustic solitons. The amplitude of the compressive/rarefactive solitons increases with the increase in negative ion concentration (α). Whereas, on increasing ionic temperature ratio (σ1 or σ2) the amplitude of the compressive/rarefactive soliton decreases. The effect of negative-ion concentration (α), temperature ratio of two ion species (σ1 and σ2), Mach number (M) and spectral index (k) on the characteristics of solitons are discussed in detail. The results of the present investigation may be helpful to understand the nonlinear ion-acoustic solitary waves in space plasma and laboratory plasmas, where two distinct groups of ions and non-Boltzmann distribution electrons are present.

Two-dimensional modulated ion-acoustic excitations in electronegative plasmas

Two-dimensional modulated ion-acoustic waves are investigated in an electronegative plasma. Through the reductive perturbation expansion, the governing hydrodynamic equations are reduced to a Davey-Stewartson system with two-space variables. The latter is used to study the modulational instability of ion-acoustic waves along with the effect of plasma parameters, namely, the negative ion concentration ratio (α) and the electron-to-negative ion temperature ratio (σn). A parametric analysis of modulational instability is carried out, where regions of plasma parameters responsible for the emergence of modulated ion-acoustic waves are discussed, with emphasis on the behavior of the instability growth rate. Numerically, using perturbed plane waves as initial conditions, parameters from the instability regions give rise to series of dromion solitons under the activation of modulational instability. The sensitivity of the numerical solutions to plasma parameters is discussed. Some exact solutions in the form one-...