• Journal of Industrial Technology
• /
• v.15
• /
• pp.15-22
• /
• 1995

We have studied the generation and behavior of negative ions in silane plasmas. The negative ions were formed by homogeneous reaction in silane plasma and the behavior of negative ions were predicted by solving the model equations. The concentration profiles of negative ions were shown as a function of reactor length and time. The effects of process variables such as reactor pressure, flow rate and electrical field strengths on the behavior of negative ions were analyzed.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.6 no.3
• /
• pp.1-8
• /
• 2003

This study was carried out in order to investigate of effects of environmental conditions which influence negative ions development. Negative ions are nature' most powerful air-cleaning agents, are created by nature, and found at their most optimal levels where the air is most pure and healthy. Negative ions are regarded as one of the important factors which indicate the quality of the air. Therefore, the focus of this study was to clear relationship among negative ions development induced by plant cultivar and environmental conditions such as air temperature, light intensity and relative humidity. As the results of this study, it was found that negative ions development was promoted during the period with plants compared to the period without plants. In Particular, negative ions development was high under air temperature $20^{\circ}C$, relative humidity 90% and dark condition. Temperature and humidity factors on this experiment was strongly affected on negative ions development, but light intensity had almost slight effect. It was shown that these results can contribute to the application of environmental control techniques to negative ions. Among plant cultivar of Spathiphyllum spp. Mentha spicata, and Cupressu arizonica, Mentha spicata was higher negative ions than the other plants, and also the leaves were higher than the stems and roots. The effect of plants on the perception of the inte끼r air quality may, therefore, be one explanation of this results about negative ions. on the other hand, it seems that a green indoor environment might be an increase in general well-being due to the plants.

• Journal of Industrial Technology
• /
• v.25 no.A
• /
• pp.141-149
• /
• 2005

We investigated numerically the evolutions of several chemical species which are important for film growth and particle generation in the pulsed $SiH_4$ plasmas. During the plasma-on, the $SiH_x$ concentration increases with time mainly by the generation reaction from $SiH_4$, but, during the plasma-off, decreases because of the hydrogen adsorption reaction. During the plasma-on, the concentrations of negative ions increase with time by the polymerization reactions of negative ions and those become almost zero in the sheath regions because of the electrostatic repulsion. During the plasma-off, the concentrations of negative ions decrease with time by the neutralization reactions with positive ions and some negative ions can diffuse toward the sheath regions because there is no electric field inside the reactor. The polymerized negative ions of higher mass can be reduced successfully by using the pulsed plasma process.

• Nuclear Engineering and Technology
• /
• v.56 no.2
• /
• pp.546-551
• /
• 2024

As an effective methods of plasma heating, neutral beam injection (NBI) systems based on negative hydrogen ion sources will be utilized in future magnetic-confinement nuclear fusion experiments. Because of the collisions between the fast negative ions and the neutral background gas, the positive ions are inevitable created in the acceleration region in the negative NBI system. These positive ions are accelerated back into the ion source and become high energy backstreaming ions. In order to explore the characters of backstreaming ions, the track and power deposition of backstreaming H⁺ beam is estimated using the experimental and simulation methods at NNBI test facility. Results show that the flux of backstreaming positive ions is 1.93 % of that of negative ion extraction from ion source, and the magnet filed in the beam source has an effect on the backstreaming positive ions propagation.

• Journal of Industrial Technology
• /
• v.14
• /
• pp.63-75
• /
• 1994

The objective of this research is to analyze the phenomena of negative ion behavior in silane plasma chemical vapor deposition. Based on the plasma chemistry, the model equations for the formation and transport of negative ions were proposed and solved. The evolutions of gaseous species along the reactor were presented for several conditions of process variables such as reactor pressure, total gas flow rate, and electric field. Based on the model results, it is found that : (1) The concentration profiles of positive ions show the sharp peaks at the center of plasma reactor. (2) Most of negative ions are located in bulk plasma region, because the negative ions are excluded from the sheath region by electrostatic repulsion.

• Journal of Environmental Science International
• /
• v.29 no.4
• /
• pp.403-413
• /
• 2020

The purpose of this study is to understand the formation of internal wind paths of open space and its effect on meteorological factors and the generation of negative air ions. Various types of internal wind paths of open space were formed. Subsequently, changes in meteorological factors in each type were measured and the generated negative air ions were analyzed. The four key findings of the study are summarized as follows. First, the average wind speed formed inside the open space was analyzed such that the difference in wind speed was dependent on the difference in the composition of the wind path. Second, the negative air ion generation was observed to have the same trend as the average wind speed difference. Third, changes to the meteorological factors were more evident depending on the difference in wind path formation patterns. Solar radiation was expected to be highly affected by the physical structure (direction) of the target site. The relative humidity was found to show large difference depending on the different wind path type; however, this difference was significantly reduced when converting to absolute humidity. Fourth, it was found that the wind path formation type of open space affects meteorological factors through path analysis, and the changed meteorological factors affect the amount of generated negative air ions. Two conclusions can be obtained based on these results. First, the changes in internal wind speed formation of open space directly reduced the amount of generated negative air ions. Second, the changes in wind speed affect meteorological factors as well as the amount of generated negative air ions.

• Proceedings of the KSME Conference
• /
• 2007.05b
• /
• pp.2344-2347
• /
• 2007

To generate negative ion, a small dielectric barrier discharge (DBD) plasma reactor was used in this study and operated by high AC voltage. With increasing of voltage, we can get more negative ions. However unfortunately, if the input voltage is too high, it will also cause formation of ozone which is very harmful to human being health. So the work of finding out the best condition of Voltage and frequency was carried out firstly. After several times of measurement, operating at 20 kHz frequency is the best condition generating high ion concentration without ozone. For the purpose of finding out the best reactor structure, two types of surface dielectric barrier discharge (DBD) reactors were examined to produce negative oxygen ions at the conditions of 20 kHz frequency. The results indicated that the surface DBD reactor with several small tips showed better characteristics for generation of negative oxygen ions at the same condition.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2010.02a
• /
• pp.470-470
• /
• 2010

Negative ions are generated in fusion edge plasmas, material processing plasmas, ionospheric plasmas. Analytic formulas for the deduction of the absolute density of negative ions was given by using the current-voltage(IV) characteristics of two electric probes at two different pressures [1], and negative ion density has been measured by one electric probe using the current-voltage characteristics of three different pressures [2]. Ratios of ion and electron saturation currents and electron temperatures and sheath areas of different pressures are usually incorporated into two equations with two unknowns for the negative ion density. In the previous publications, the sheath factor(sheath area, sheath density, sheath velocity) and effective masses of background ions with different pressures are qualitatively incorporated for the deduction of negative density. In this presentation, the quantitative and detailed relation of negative ion density with sheath factor and effective masses are going to be given. The effect of these parameters on the change of IV characteristics will be addressed.

• Journal of Korean Society of Forest Science
• /
• v.97 no.4
• /
• pp.423-430
• /
• 2008

Negative ion is considered as one of the forest health attributes. The overall purpose of this study was to investigate the influence of air negative ions on physiological effects. Data were collected from 12 volunteers (university students) who were randomly assigned into treatment and control groups. Subjects in treatment group were exposed to air with negative (2,001,000 ion/cc). Using pretest-posttest control group design, blood cortisol, norepinephrine, epinephrine, and cognitive function were measured. Data analysis indicated that negative ions influenced on positive effects of stress responses.

• Journal of Electrical Engineering and Technology
• /
• v.8 no.5
• /
• pp.1175-1181
• /
• 2013

The aim of this paper is to design and evaluate a high concentration, high penetration unipolar corona ionizer. The electrostatic characteristics in terms of voltage-current relationships of the present ionizer in the discharge zones for positive and negative coronas were discussed. Using ion current measurement, the concentration and penetration of ions were evaluated at corona voltages across the needle electrodes between 1 and 4 kV, flow rates between 1 and 5 L/min, and an operating pressure of 1 atm. In the discharge zone of the ionizer, the highest ion concentrations were found to be about $1.71{\times}10^{14}$ and $5.09{\times}10^{14}\;ions/m^3$ for positive and negative coronas, respectively. At the outlet of the ionizer, it was found that the highest ion concentration was about $1.95{\times}10^{13}$ and $1.91{\times}10^{13}\;ions/m^3$ for positive and negative coronas, respectively. The highest ion penetration for positive and negative coronas through the ionizer was found to be about 98 % and 33 %, respectively. The $N_it$ product for positive and negative coronas was also found to $1.28{\times}10^{13}$ and $7.43{\times}10^{13}\;ions/m^3s$, respectively. From the findings, this ionizer proved to be particularly useful as an aerosol charger for positive and negative charge before the detector in an electrical aerosol detector.