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1.
Dielectric barrier discharge (DBD) for SOs removal from indoor air is investigated. In order to improve the removal efficiency, two novel methods are combined in this paper, namely by applying a pulsed driving voltage with nanosecond rising time and applying a magnetic field. For SOs removal efficiency, different matches of electric field and magnetic field are discussed. And nanosecond rising edge pulsed power supply and microsecond rising edge pulsed power supply are compared. It can be concluded that a pulsed DBD with nanosecond rising edge should be adopted, and electrical field and magnetic field should be applied in an appropriate match.  相似文献   

2.
Dynamics of dust in a plasma sheath with a magnetic field was investigated using a single particle model. The result shows that the radius, initial position, initial velocity of the dust particles and the magnetic field do effect their movement and equilibrium position in the plasma sheath. Generally, the dust particles with the same size, whatever original velocity and position they have, will locate at the same position in the end under the net actions of electrostatic, gravitational, neutral collisional, and Lorentz forces. But the dust particles will not locate in the plasma sheath if their radius is beyond a certain value.  相似文献   

3.
An atmospheric non-thermal plasma jet was developed for sterilizing the Staphylococcus aureus (S. aureus). The plasma jet was generated by dielectric barrier discharge (DBD), which was characterized by electrical and optical diagnostics. The survival curves of the bacteria showed that the plasma jet could effectively inactivate 10 6 cells of S. aureus within 120 seconds and the sterilizing efficiency depended critically on the discharge parameter of the applied voltage. It was further confirmed by scanning electron microscopy (SEM) that the cell morphology was seriously damaged by the plasma treatment. The plasma sterilization mechanism of S. aureus was attributed to the active species of OH, N 2 + and O, which were generated abundantly in the plasma jet and characterized by OES. Our findings suggest a convenient and low-cost way for sterilization and inactivation of bacteria.  相似文献   

4.
Atmospheric pressure non-thermal plasma is of interest for industrial applications. In this study, polypropylene (PP) films are modified by a dielectric barrier discharge (DBD) with a non-uniform magnetic field in air at atmospheric pressure. The surface properties of the PP films before and after a DBD treatment are studied by using contact angle measurement, atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The effect of treatment time on the surface modification with and without a magnetic field is investigated. It is found that the hydrophilic improvement depends on the treatment time and magnetic field. It is also found that surface roughness and oxygen-containing groups are introduced onto the PP film surface after the DBD treatment. Surface roughness and oxygen-containing polar functional groups of the PP films increase with the magnetic induction density. The functional groups are identified as C-O, C=O and O-C=O by using XPS analysis. It is concluded that the hydrophilic improvement of PP films treated with a magnetic field is due to a greater surface roughness and more oxygen-containing groups.  相似文献   

5.
Field-reversed configurations (FRCs) driven by rotating magnetic fields (RMFs) with spatial high-harmonic components have been studied in the metal flux conserver of the FRC injection experiment (FIX). The high-harmonic RMF method has some unique features; (1) field lines of the RMF do not penetrate or cross the vessel wall, (2) selective penetration/exclusion of the fundamental/high-harmonic RMF component will result in a generation of effective magnetic pressure near the separatrix, which helps to keep the separatrix away from the vessel wall, (3) strong azimuthal non-uniformity of the RMF will cause the n = 4 deformation of the core FRC plasma, which will eliminate the destructive modes caused by the rotation of the plasma column. The RMF method with high harmonics will provide quasi-steady current drive of high-beta FRC plasmas without destructive n = 2 rotational mode and will be helpful in reducing the particle loss and thermal load when applied to the fusion core plasma.  相似文献   

6.
A single-stage plasma-catalytic reactor in which catalytic materials were packed was used to remove nitrogen oxides. The packing material was scoria being made of various metal oxides including Al2O3, MgO, TiO2, etc. Scoria was able to act not only as dielectric pellets but also as a catalyst in the presence of reducing agent such as ethylene and ammonia. Without plasma discharge, scoria did not work well as a catalyst in the temperature range of 100℃ to 200℃, showing less than 10% of NOx removal efficiency. When plasma is produced inside the reactor, the NOx removal efficiency could be increased to 60% in this temperature range.  相似文献   

7.
The electromagnetic wave growth or damping depends basically on the number density and anisotropy of energetic particles as the resonant interaction takes place between the particles and waves in the magnetosphere. The variance of both the number density and anisotropy along the magnetic field line is evaluated systematically by modeling four typically prescribed distribution functions. It is shown that in the case of "the positive anisotropy" (namely, the perpendicular temperature T⊥ exceeds the parallel temperature T||), the number density of energetic electrons always decreases with the magnetic latitude for a regular increasing magnetic field and the maximum wave growth is therefore generally confined to the equator where the resonant energy is minimum, and the number density is the largest. However, the "loss-cone" anisotropy of the electrons with a "pancake" distribution or kappa distribution keeps invariant or nearly invariant, whereas the "temperature" anisotropy with a pure bi-Maxwellian distribution or Ashour-Abdalla and Kennel's distributions decreases with the magnetic latitude. The results may provide a useful approach to evaluating the number density and anisotropy of the energetic electrons at latitudes where the observation information is not available.  相似文献   

8.
A distribution of the magnetic field produced by permanent magnets in the DNB ion source is calculated and analyzed in order to understand the plasma confinement in a cusped magnetic field and optimize plasma discharge. A uniform plasma is obtained in the experiment.  相似文献   

9.
Our experiment shows that the dust grains ,suspended on the edge of the sheath of a radio-frequency discharge,undergo a contraction when switching a vertical magnetic field on ,and an expansion when switching the magnetic field off .We call this kind of magnetic field“transient magnetic field”.A primary analysis is proposed for the phenomenon.  相似文献   

10.
The kinetics mechanism of the dissociation reactions in a NO/SO2/N2/O2 system was investigated in consideration of energetic electrons' impacts on a non-thermal plasma. A model was derived from the Boltzmann equation and molecule collision theory to predict the dissociation reaction rate coefficients. Upon comparison with available literature, the model was confirmed to be acceptably accurate in general. Several reaction rate coefficients of the NO/SO2/N2/O2 dissociation system were derived according to the Arrhenius formula. The activation energies of each plasma reaction were calculated by quantum chemistry methods. The relation between the dissociation reaction rate coefficient and electron temperature was established to describe the importance of each reaction and to predict relevant processes of gaseous chemical reactions. The sensitivity of the mechanism of NO/SO2/N2/O2 dissociation reaction in a non-thermal plasma was also analysed.  相似文献   

11.
The Helimak of USA is a plasma physics experimental device designed and built by CASIPP.Its configuration of magnetic field is of very importance during the operation of this device.In this paper,the influence of magnetic permeability on configuration of magnetic field will be discussed due to the effect of weld metal in the vacuum vessel of Helimak,and some conclusion is useful for some engineering designs of the fusion experimental device.  相似文献   

12.
This article presents a study we have made of one class of coherent structures of the tripolar vortex. Considering the sheared flow and sheared magnetic field which are common in the thermonuclear plasma and space plasma, we have simulated the dynamics of the tripolar vortex. The results show that the tripolar vortex is largely stable in most cases, but a strongly sheared magnetic field will make the structure less stable, and lead it to decays into single vortices with the large space scale. These results are consistent with findings from former research about the dipolar vortex.  相似文献   

13.
Magnetoelectric heating was used to heat ions in an ECR plasma with a magnetic mirror field.The temperature and density of ions were measured by an ion sensitive probe(ISP) before and after magnetoelectric heating in order to investigate the influence of the anode ring’s radius,axial position and working pressure on magnetoelectric heating.Results showed that a suitable radius of the anode ring could improve the ion temperature effectively and the optimal size of the anode ring depended on the cyclotron radius of ions.The radial uniformity of the ion density was improved by increasing the radius of the anode ring after heating.The magnetic mirror field could reduce the loss of ions caused by collision with the wall of the chamber and it was beneficial to increase the ion temperature and the ion density.It was suitable to heat the ions when the anode ring was set at the center of the magnetic mirror field where there was a weaker magnetic field strength.Lower pressure contributed to the increase in the ion temperature and efficiency of magnetoelectric heating.  相似文献   

14.
A one-dimensional radial non-uniform fluid model is employed to study plasma behaviors with special emphasis laid on helicon discharges. The plasma density ne, electron temperature Te, electron azimuthal and radial drift velocities are investigated in terms of the plasma radius rp, magnetic field intensity B0 and gas pressure p0, by assuming radial ambipolar diffusion and negligible ion cyclotron movement. The results show that the magnetic confinement plays an important role in the discharge equilibrium, especially at low pressure, which significantly reduces Te compared with the case of a negligible magnetic field effect, and higher B0 leads to a greater average plasma density. Te shows little variations in the plasma density range of 1011 cm-3- 1013 cm-3 for p0 〈 3.0 mTorr. Comparison of the simulation results with experiments suggests that the model can make reasonable predictions of Te in low pressure helicon discharges.  相似文献   

15.
Based on magnetohydrodynamic (MHD) model of vacuum arc, the computer simulation of vacuum arc was carried out in this paper. In the MHD model, mass conservation equation, momentum conservation equations, energy conservation equations, generalized ohm‘s law and Maxwell equation were considered. MHD equations were calculated by numerical method, and the distribution of vacuum arc plasma parameters and current density were obtained. Simulation results showed that the magnetic constriction effect of vacuum arc is primarily caused by the Hall effect. In addition, the inhibition of axial magnetic field (AMF) on constriction of vacuum arc was calculated and analyzed.  相似文献   

16.
Application of plasma chemistry for gas cleaning is gaining prominence in recent years, mainly from an energy efficiency point of view. In this paper we conducted a comparative study of NO/NOx removal using two different types of dielectric barrier discharge electrodes, wire- cylinder reactor, pipe-cylinder reactor. Investigations were first carried out with synthetic gases to obtain the baseline information on the NO/NOx removal with respect to the two geometries studied. Further, experiments were carried out with raw diesel exhaust under loaded condition. A high NOx removal efficiency of 90% was observed for the pipe-cylinder reactor as compared to that of 53.4% for the wire-cylinder reactor. Furthermore, for the same energy consumed per NO molecule (about 73 eV/NO molecule), the removal efficiency increased from 67% for the wire- cylinder to about 98% for the pipe-cylinder which was quite appreciable.  相似文献   

17.
For a rectangular planar direct current (DC) magnetron, anomalous target erosion may occur in the curve-out region and inner side of the curved region. One key factor is that the magnetic field in the end region is weaker than that in the straight region, and another important factor may be that there is a circumferential component of the magnetic field in the curved region. Through a calculation of three-dimensional magnetic field for the rectangular magnetron, a magnet structure shimmed by permanent magnet bars and ferromagnetic bars is proposed to solve the above problems. Through a three-dimensional non-self-consistent particle simulation and the Yamamura/Tawara formula, the target erosion profile could be predicted. The simulation results show that for an improved uniformity in magnetic field, the entire target utilization could be much enhanced.  相似文献   

18.
Thermodynamic energy conversion in a plasma stream, flowing across a magnetic field, is studied. Due to the unique combination of compressibility with electrical conductivity, the expansion work of the plasma stream is converted directly into electromagnetic energy. Consideration of electromagnetic phenomena, according to Poynting's theorem, as energy transport processes revealed that the new electromagnetic energy source can maintain a steady electric vortex in the system at rest relative to the magnetic field, which is constant in time. Thus, Maxwell's equations of the electromagnetic field have an additional term in plasma systems. This unexpected result may well be the key to the development of fusion power.  相似文献   

19.
A major obstacle to the broad application of cathodic arc plasma deposition is the presence of macroparticles. In this paper, the properties of the large rectangular arc ion plating with a magnetic filtering shutter system to filter macroparticles are studied. It is proposed that the macroparticles in the plasma beam are effectively removed with the magnetic filtering shutter system, and the quality of the deposited films is improved.  相似文献   

20.
The Levitated Dipole Experiment (LDX) explores confinement and stability of plasma created within the dipole field of a strong superconducting magnet. During initial experiments, long-pulse, quasi-steady state discharges that last more than 10 s and have peak beta of more than 20% are studied. The plasma is created by multi-frequency electron cyclotron resonance heating (ECRH) at 2.45 and 6.4 GHz. A population of energetic electrons, with mean energies above 50 keV, dominates the plasma pressure. Creation of high pressure, high beta plasma is possible only when intense hot electron interchange (HEI) instabilities are stabilized by sufficient neutral gas fueling. The instabilities resonate with the magnetic drift motion of the energetic electrons and can cause rapid radial transport. Measurements of the electrostatic and magnetic fluctuations of the HEI instability are described along with observations of the instability’s spectral characteristics. Fluctuations of the outer poloidal field induced by the HEI show a rapid evolution of the perturbed pressure profile.   相似文献   

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