Inter-Calibration Between Plasma Instruments Onboard DEMETER

The in-situ measurements of the ionospheric plasma that we use come from two instruments of the scientific payload of the satellite DEMETER; the plasma analyser IAP （Instrument d＇analyse du plasma） and the Langmuir probe ISL （Instrument Sonde de Langmuir）. DEMETER is a micro-satellite realized by the CNES（Centre National d＇Etudes Spatiales, France） with a principal objective to seek a possible influence of the seismic activity on the electromagnetic waves in the ionosphere and on the ionospheric plasma. The satellite was placed on June 29, 2004, in a circular and quasi helio-synchronous orbit at -710 km altitude. The experiments function primarily at mid-latitudes （from ＋60° to -60°）. The IAP data were analysed to deduce the ion population （densities of the dominant ions, i.e. generally O^＋, H^＋ and He^＋） therefore the total ion density. The use of data IAP thus requires some precaution to make sure that the electric equilibrium conditions of the satellite, such as the satellite potential （Фsat）, are obtained during the treatment of routine, does not induce an error of measurement. When this potential is negative, the minority light ions H^＋ and He^＋ can be measured in a reliable way when their proportion is above 3% to 5% of that of O^＋. The critical limitation is： under certain conditions, the satellite potential becomes positive and reach a value about -0.5 V so that it becomes impossible to measure H^＋ ions. This is likely to involve a significant error on the composition and the density of the plasma. Therefore we carried out a calibration to estimate the missing density. The ISL experiment （Langmuir probe） provided the collected current/polarized tension characteristics of a cylindrical probe from which both electron density Ne and temperature Te were obtained. In some situations it is necessary to examine the accuracy of the electron density using another technique, for instance the high frequency （HF） spectrogram, provided by ICE （instrument champ     

The Effects of Low-Energy Nitrogen Ion Implantation on Pollen Exine Substructure and Pollen Germination of Cedrus deodara

The aim of this study is to investigate the biological effects of ion beams on pollen. Pollen grains of Cedrus deodara were implanted with 30 keV nitrogen ion beams at doses ranging from 1 × 10^15 ions/cm^2 to 15 × 10^15 ions/cm^2. The effects of N^＋ implantation on the pollen exine substructure were examined using an atomic force microscope （AFM）, and the structure and morphology of pollen and pollen tubes were observed using a laser scanning confocal microscope （LSCM）. AFM observations distinctly revealed the erosion of the pollen exine caused by N^＋ implantation in the micrometer to nanometer range. Typical results showed that the erosion degree was linearly proportional to the ion dose. Pollen germination experiments in vitro indicated that N^＋ implantation within a certain dose range increased the rate of pollen germination. The main abnormal phenomena in pollen tubes were also analyzed. Our results suggest that low energy ion implantation with suitable energy and dosage can be used to break the pollen wall to induce a transfer of exogenous DNA into the pollen without any damage to the cytoplasm and nuclei of the pollen. The present study suggests that a combination of the method of ion-beam-induced gene transfer and the pollen-tube pathway method （PTPW） would be a new plant transformation method.     

Degradation of Anionic Dye Eosin by Glow Discharge Electrolysis Plasma

This paper describes a novel method for the degradation of eosin by using glow discharge electrolysis （GDE）. The effects of various parameters on the removal efficiency were studied. It was found that the eosin degradation could be raised considerably by increasing the applied voltage and the initial concentration, or by decreasing pH of the aqueous solution. Fe^2＋ ion had an evident accelerating effect on the eosin degradation. The degradation process of eosin obeyed a pseudo-first-order reaction. The relationship between the degradation rate constant k and the reaction temperature T could be expressed by Arrhenius equation with which the apparent activation energy Ea of 14.110 kJ· mol^-1 and the pre-exponential factor k0 of 2.065× 10^-1 min^-1 were obtained, too. The determination of hydroxyl radical was carried out by using N, N-dimethyl -p-nitrosoaniline （RNO） as a scavenger. The results showed that the hydroxyl radical plays an important role in the degradation process.     

Generation and Distribution of Fast Atomic Species（N^＋, Nf） in Nitrogen Glow Discharge

Using a combination of the Monte Carlo models of fast electrons, of molecular ions （N＋） and of atomic species （N^＋, Nf）, the influence of the discharge pressure （P） and voltage （Vc） on the energy distributions of fast atomic species （N^＋, Nf） produced by e^--N2s and N2^＋- N2s dissociation reactions at the cathode in a nitrogen dc glow discharge was investigated. Both the angular distributions and the density distributions along the radius of the species （N^＋, Nf） produced by the two dissociations at the cathode were calculated. The results show that： （1） there is an optimum discharge condition for P and Vc in order to obtain the species （N^＋, Nf） at the cathode with high a density and energy, （2） when the voltage is above 800 V, the species （N^＋, Nf） bombarding the cathode are mainly produced by the N^＋-N2s dissociation, whereas when the voltage is below 300 V, they are mainly produced by the e-N2s dissociation, and （3） at high Voltages the incident angles of a considerable number of Nf into the cathode are quite small. The density of the species （N^＋ Nf） at the cathode increases with the voltage, and when the pressure goes up to about 133 Pa, it decreases with the increasing pressure.     

Mass Deposition,Etching and Sputtering Effects of Low-Energy N~+ Ion Irradiation on Solid Fly Ash

Fly ash is an industrial waste created when coal is burned to generate electrical power. In the present study, we used low-energy nitrogen ion implantation on fly ash to improve its surface properties. Scanning electron microscope （SEM）, fourier transform infrared spectroscopy （FTIR）, X-ray photoelectron spectroscopy （XPS） and inductively coupled plasma-atomic emission spectroscopy （ICP-AES） were used to study the changes of physical and chemical properties of fly ash after N＋ ion implantation, and the mechanism of fly ash modified by ion implantation. In the optimal implantation with energy of 5 keV and dose Of 15D0, the ion beam could effectively increase the specific surface area （approximately 150% increase） of the fly ash. Lots of scratches were generated in the surface of the fly ash after N＋ ion implantation, therefore it is good for enhancing the specific surface area. Experimental results show that the ion implantation could open the chemical bonds of Si-O, Si-A1 and Al-O, and deposit nitrogen ions on the surface of fly ash.     

Effect of Addition of Nitrogen to a Capacitively Radio-Frequency Hydrogen Discharge

A hybrid PIC/MC model is developed in this work for H2-xN2 capacitively coupled radio-frequency （CCRF） discharges in which we take into account 43 kinds of collisions reaction processes between charged particles （e-, H3＋, H＋, H＋, N＋, N＋） and ground-state molecules （H2, H＋ N2）. In addition, the mean energies and densities of electrons and ions （ 3, H＋, H＋）, and electric field distributions in the H2-N2 CCRF discharge are simulated by this model. Furthermore, the effects of addition of a variable percentage of nitrogen （0-30%） into the H2 discharge on the plasma processes and discharge characteristics are studied. It is shown that by increasing the percentage of nitrogen added to the system, the RF sheath thickness will narrow, the sheath electric field will be enhanced, and the mean energy of hydrogen ions impacting the electrodes will be increased. Because the electron impact ionization and dissociative ionization rates increase when N2 is added to the system, the electron mean density will increase while the electron mean energy and hydrogen ion density near the electrodes will decrease. This work aims to provide a theoretical basis for experimental studies and technological developments with regard to H2-N2 CCRF plasmas.     

Adsorption behavior of Zr（IV） and Hf（IV） on a silica-based macroporous TODGA adsorbent

In order to separate Zr（IV） and Hf（IV） in acidic solution, several kinds of silica-based macroporous adsorbents were synthesized. Their adsorption selectivity for Zr（IV） and Hf（IV） in HCl solution was investigated, and the TODGA adsorbent for the two elements had the largest adsorption difference. The effects of acid type, HCl concentration, and temperature on the adsorption behavior of Zr（IV） and Hf（IV） onto the TODGA adsorbent were conducted by batch experiments. It was found that H＋ exhibited a quite strong influence on adsorption capacity of Zr（IV） and Hf（IV）. Isotherm fitting showed that the Langmuir model agrees well with the experimental data. The thermodynamic parameters indicate that the adsorption processes for both elements are endothermic reactions. The TODGA adsorbent had the higher adsorption selectivity for Zr（IV） over Hf（IV） and could be promising for their mutual separation.     

Influence of Yttrium Ion-Implantation on the Growth Kinetics and Micro-Structure of NiO Oxide Film

Isothermal and cyclic oxidation behaviours of pure and yttrium-implanted nickel were studied at 1000℃ in air. Scanning electronic microscopy （SEM） and transmission electronic microscopy （TEM） were used to examine the micro-morphology and structure of oxide scales formed on the nickel substrate. It was found that Y-implantation significantly improved the anti- oxidation ability of nickel in both isothermal and cyclic oxidizing experiments. Laser Raman microscopy was also used to study the stress status of oxide scales formed on nickel with and without yttrium. The main reason for the improvement in anti-oxidation of nickel was that Y- implantation greatly reduced the growing speed and grain size of NiO. This fine-grained NiO oxide film might have better high temperature plasticity and could relieve parts of compressive stress by means of creeping, and maintained a ridge character and a relatively low internal stress level. Hence yttrium ion-implantation remarkably enhanced the adhesion of protective NiO oxide scale formed on the nickel substrate.     

Frequency dependence of electron temperature in hollow cathode-type discharge as measured by several different floating probe methods

We measured electron temperatures through a hollow cathode-type discharge tube using several different floating probe methods.This method detected a shift in the floating potential when an AC voltage was applied to a probe through an intermediary blocking capacitor.The shift in the floating potential is described as a function of the electron temperature and the applied AC voltage.In this study,the effects of the frequency and waveform on the electron temperatures were systematically investigated.The electron temperature measured when using the floating probe method with applied sinusoidal and triangular voltages was lower than that measured with an applied rectangular voltage.The value in the high frequency range was close to that of the tail electron temperature.     

Plasma Response to Supersonic Molecular Beam Injection in J-TEXT简

Recently, hydrogen fueling experiments with supersonic molecular beam injection （SMBI） system have been performed in the J-TEXT tokamak. To evaluate the effects of the in- jection amount of SMBI on plasma behaviors, moderate and intensive SMBs have been separately injected and compared with each other in Ohmic discharges. With moderate SMBs, electron den- sity increases about twice as before, the size of magnetic island slightly decreases, and the edge toroidal rotation speed in a counter-current direction, measured by a high resolution spectrometer （Carbon V ion, 227.09 nm, r/a-= 0.7-0.8）, is accelerated from 8 km/s to 12 km/s. The state of higher electron density with moderate SMBI can be maintained for a long period, which indicates that plasma confinement is improved. However, with intensive SMBs, the accompanied magne- tohydrodynamic （MHD） activities are triggered, and the electron density increases moderately. The edge toroidal velocity is decreased, in certain cases even reversed in the co-current direction. The statistical result of experimental data for moderate and intensive SMBs suggests a preferred fueling amount （less than 3.2 ~ 1019） to improve the SMBI fueling efficiency in experiments.     

The Effect of Gas Flow Rate on Radio-Frequency Hollow Cathode Discharge Characteristics

It is known that gas flow rate is a key factor in controlling industrial plasma processing. In this paper, a 2D PIC/MCC model is developed for an rf hollow cathode discharge with an axial nitrogen gas flow. The effects of the gas flow rate on the plasma parameters are calculated and the results show that： with an increasing flow rate, the total ion（N＋2, N＋） density decreases, the mean sheath thickness becomes wider, the radial electric field in the sheath and the axial electric field show an increase, and the energies of both kinds of nitrogen ions increase;and, as the axial ion current density that is moving toward the ground electrode increases, the ion current density near the ground electrode increases. The simulation results will provide a useful reference for plasma jet technology involving rf hollow cathode discharges in N2.     

Electron Heat Diffusivity Measurement by Perturbative Method on HT-7 Tokamak

Spatio-temporal evolutions of the sawteeth activities are measured simultaneously with a 16 channel high spatio-temporal resolution electron cyclotron emission （ECE） heterodyne radiometer on HT-7 and the evolutions of the sawteeth are found to be diffusive in character. By a perturbative analysis, the electron heat diffusivity Хe inferred by time-to-peak method and Fourier transform shows a good agreement. The value of electron heat diffusivity shows radial asymmetry between the low magnetic field side （LFS） and the high magnetic field side （HFS）. It is observed that with the increase in plasma density, the electron heat diffusivity decreases and the confinement of energy is improved. By comparing with Хe^pb inferred by static power balance analysis, the result indicate that Хe^hp is larger than Хe^pb by a factor ranging from 2 to 10.     

Evolution of Striation in Pulsed Glow Discharges

In this work,striations in pulsed glow discharges are studied by experiments and Particle-In-Cell/Monte Carlo Collision (PIC/MCC) simulation.The spatio-temporal evolution of the potential and the electron energy during the discharge are analyzed.The processes of striation formation in pulsed glow discharges and dielectric barrier discharges (DBD) are compared.The results show that the mechanisms of striation in pulsed DC discharge and DBD are similar to each other.The evolution of electron energy distribution function before and after the striation formation indicates that the striation results from the potential well of the space charge.During a pulsed breakdown,the striations are formed one by one towards the anode in a weak field channel.This indicates that the formation of striations in a pulsed discharge depends on the flow of modulated electrons.     

Ion Bernstein Wave Heating Experiments in HT-7 Superconducting Tokamak

Ion bernstein wave （IBW） experiments have been carried out in HT-7 superconducting tokamak in recent years. The electron heating experiments concentrated on deuterium plasma with an injected RF power up to 350 kW. The global heating and the localized heating can be seen clearly by adjusting the ICRF resonance layer positions. The on-axis and the off-axis electron heating were realized by arranging the target plasma parameters properly. Experimental results show that the maximum increment of electron temperature was more than 1 keV, the electron temperature profile was modified by IBW under different plasma conditions and the improvements of both energy and particle confinements have been obtained.     

Electromagnetic Wave Attenuation in Atmospheric Pressure Plasma

When an electromagnetic （EM） wave propagates in an atmospheric pressure plasma （APP） layer, its attenuation depends on the APP parameters such as the layer width, the electron density and its profile and collision frequency between electrons and neutrals. This paper proposes that a combined parameter -the product of the line average electron density n and width d of the APP layer （i.e., the total number of electrons in a unit volume along the wave propagation path） can play a more explicit and decisive role in the wave attenuation than any of the above individual parameters does. The attenuation of the EM wave via the product of n and d with various collision frequencies between electrons and neutrals is presented.     

Simulation Studies of Rib Structure Effect on Discharge Characteristics of Plasma Display Panel

To investigate the effect of the rib structure on the discharge characteristics of the plasma display panel, the potential distribution, particles density distribution and ions incident angle distribution were examined by simulation of a two-dimensional particle-in-cell/Monte Carlo collision, with two kinds of rib structure： the stripe rib structure and the Waffle rib structure. The results showed that the distribution of electric potential at the corner of the discharge cell was almost the same for these two rib structures while in the centre there was a difference between these two rib structures. The striation phenomenon could be observed in both cases. The distribution of density also indicated that the striation phenomenon was accompanied by the firing of discharge, and the Waffle rib structure might reduce the density humps. In the cell with a stripe rib structure, the profiles of the surface charge density along the sustained dielectric layer presented a better fluctuating distribution than that in the cell with a Waffle rib structure. The spatial potential and particle density in the discharge bulk showed that the Waffle ribs could weaken the striation phenomenon, which could be explained by the decrease in the particle numbers in the discharge cell. The simulation results of the ion incident angle showed that most ions impacted the sustained dielectric layer in the normal stripe rib cell with an incident angle in the range of 6° to 19° while with the Waffle rib structure the incident angle of most ions was in the range of 4° to 19°. The Waffle rib structure did not affect the angle distribution of incident ions significantly.     

Cytotoxicity of fullerenols on Tetrahymena pyriformis

With the increasing use of fullerenes and their derivatives in a variety of fields, the toxicity and effects of fullerenes on humans and the environment have received considerable attention. In this study, the cytotoxicity of fullerene derivative, C60（OH）x, on Tetrahymena pyriformis was investigated. Cell growth inhibition was evaluated by counting with an optical microscope, and the generation time was calculated. It was indicated that the fullerenols caused a dose-dependent growth inhibition of the cells. The morphologic change in the damaged macronucleus of cells was observed using a fluorescent microscope. Superoxide dismutase （SOD）, glutathione peroxidase （GSH-PX）, and glutathione reductase （GR） levels were also measured for Tetrahymena pyriformis, using conventional methods. The results showed that fullerenols could reduce GSH-PX and GR activities. But no noticeable difference in SOD activity was observed between the treated groups and the control group. This indicated that the antiproliferative effect of fullerenols might be mediated by the reduction in the activities of GSH-PX and GR of cells and the destruction of the macronucleus.     

Propagation of Electromagnetic TM （S-Polarization） Mode in Two-Dimensional Atmospheric Plasma

The finite-difference-time-domain （FDTD） method is applied to simulate the twodimensional propagation of electromagnetic TM （S-polarization） mode in atmospheric plasma and in metal layer for strong electron-neutral collisions. Dependence of the wave attenuation on both plasma parameters and incident wave angle are obtained. It is indicated that for a given electron density profile the attenuation depends strongly on the incident angle, the wave frequency, the width of plasma layer, and the collision frequency between electrons and neutrals.     

Room Temperature Growth of Hydrogenated Amorphous Silicon Films by Dielectric Barrier Discharge Enhanced CVD

Hydrogenated amorphous silicon （a-Si： H） films were deposited on Si （100） and glass substrates by dielectric barrier discharge enhanced chemical vapour deposition （DBD-CVD） in （SiH4＋H2） atmosphere at room temperature.
Results of the thickness measurement, SEM （scanning electron microscope）, Raman, and FTIR （Fourier transform infrared spectroscopy） show that with the increase in the applied peak voltage, the deposition rate and network order of the films increase, and the hydrogen bonding configurations mainly in di-hydrogen （Si-H2） and poly hydrogen （SiH2）n are introduced into the films. The UV-visible transmission spectra show that with the decrease in SiH4/ （SiHn＋H2） the thin films＇ band gap shifts from 1.92 eV to 2.17 eV.
These experimental results are in agreement with the theoretic analysis of the DBD discharge. The deposition of a-Si： H films by the DBD-CVD method as reported here for the first time is attractive because it allows fast deposition of a-Si： H films on large-area low-melting-point substrates and requires only a low cost of production without additional heating or pumping equipment.     

Numerical Research of Mode Conversion in an Inhomogeneous Plasma

The linear mode conversion of electromagnetic waves in the hot, unmagnetized inhomogeneous plasma is studied numerically for different density profiles, and the dependence of the absorption coefficient on the incident angles and the wave frequencies are obtained for different electrons＇ temperature. The results show that the shapes of the density profiles and the electron＇s temperature create a certain effect on the coefficients of absorption, which reaches its peak value （about 50%） for appropriate parameters. Effective absorption occurs in a limited range of parameter q.