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Self-organized spatial structures in the light emission from the ion-ion capacitive rf plasma of a strongly electronegative gas (CF_{4}) are observed experimentally for the first time. Their formation is analyzed and understood based on particle-based kinetic simulations. These "striations" are found to be generated by the resonance between the driving radio frequency and the eigenfrequency of the ion-ion plasma (derived from an analytical model) that establishes a modulation of the electric field, the ion densities, as well as the energy gain and loss processes of electrons in the plasma. The growth of the instability is followed by the numerical simulations.

In this paper, intense pulsed electron beam was used for the irradiation treatment of 6–8% Y 2 O 3 -stablized ZrO 2 thermal barrier coating prepared by electron beam-physical vapor deposition to achieve the “sealing” of columnar crystals, thus improving their thermal insulation properties and high temperature oxidation resistance. The electron beam parameters used were: pulse duration 200 μs, electron voltage 15 kV, energy density 3, 5, 8, 15, 20 J/cm 2 , and pulsed numbers 30. 1050 °C cyclic oxidation and static oxidation experiments were used for the research on oxidation resistance of the coatings. When the energy density of the electron beam was larger than 8 J/cm 2 , ZrO 2 ceramic coating surface was fully re-melted and became smooth, dense and shiny. The coating changed into a smooth polycrystalline structure, thus achieving the “sealing” effect of the columnar crystals. After irradiations with the energy density of 8–15 J/cm 2 , the thermally grown oxide coating thickness decreased significantly in comparison with non-irradiated coatings, showing that the re-melted coating improved the oxidation resistance of the coatings. The results of thermal diffusivity test by laser flash method showed that the thermal diffusion rate of the irradiated coating was lower than that of the coating without irradiation treatment, and the thermal insulation performance of irradiated coating was improved.

In this work, we review current trends in China to investigate beam plasma interaction phenomena. Recent progresses in China on low energy heavy ions and plasma interaction, ion beam-plasma interactions under the influences of magnetic fields, high energy heavy ion radiography through marginal range method, energy deposition of highly charged ions on surfaces and Raman spectroscopy of surfaces after irradiation of highly charged ions are presented.

This paper presents numerical simulations to study the heating of a two-dimensional (2D) solid target under an ion cluster interaction. 2D quantum hydrodynamic (QHD) model is employed for the heating of solid target to warm dense matter on a picosecond time scale. A Gaussian cluster is used to uniformly heat the solid target to a temperature of several eV. The density and temperature of the target are calculated by a full self-consistent treatment of the QHD formalisms and the Poisson's equation. The technique described in this paper provides a method for creating uniformly heated strongly coupled plasma states.

Capacitively coupled plasma (CCP) is one of the most common industrial plasma sources. Experimental characterization plays key roles in understanding the complex physics involved in CCP, and is based on various probes, optical monitoring and mass spectrometry. Some recent configurations of capacitive discharge like dual frequency CCP, direct current CCP and electric asymmetric CCP have been extensively studied experimentally with these methods. In this paper, we review these recent experimental progresses of CCP studies.

In this paper, the DZ4 Ni-based superalloy was irradiated by high intensity pulsed C ion and H ion beam. The parameters of ion beam were: accelerating voltage 250 kV, pulse duration 70 ns, ion current density 160 A/cm2. Irradiation pulses were 2, 5, 10 and 15. The morphology of DZ4 before and after irradiation was observed by scanning electron microscope (SEM). The phase structure and stress state were analyzed by X-ray diffraction (XRD). The results show that there were some craters on the surface of the sample after irradiation, as the irradiation time increased, the crater boundary became blurred and even disappeared. The surface tensile stress produced by initial irradiation could be relieved after several irradiations pulses. The corrosion resistance of irradiated DZ4 alloy was improved greatly. The continuous and dense α-Al2O3 layer that formed on irradiated DZ4 surface at 1000°C atmosphere increased the high temperature oxidation resistance.

The thermal barrier coatings (TBC) of the yttria-stabilized zirconia (YSZ) has been deposited by the atmospheric plasma spraying (APS),followed by the irradiation of high intensity pulsed ion beam (HIPIB) with the voltage of 250 KV and the ion current density of 300 A/cm2 and pulsed times of 2, 5, 10 and 20, respectively. The X-ray diffraction (XRD) analysis reveals that the coating is characterized by the tetragonal ZrO2 phase instead of the cubic phase and the original monoclinic phase after the irradiation. The scanning electron micros cope analysis demonstrates that the HIPIB treatment leads to a smooth TBC surface, but produces micro-cracks and round grain at the surface. This implies that the plasma erupts during the ion beam interaction with the coatings with poor thermal conductivity, and the micro-cracks were produced in the cooling process. The isothermal oxidation experiment performed at 1050°C in air and suggests that the oxidation resistance of the coating can be largely enhanced after HIPIB treatment.

A complete floating double probe technique is used to measure the ion density and electron temperature in a dual frequency capacitively coupled plasma for argon discharges. It has been shown that there is an obvious modulating effect of the high- and low-frequency powers on the plasma parameters and their spatial distributions. In addition, the influence of the discharge gap on the ion density and electron temperature is also investigated by varying the LF power and fixed the HF power.

Driven by pulse modulated radio-frequency source, the behavior of SiH4/N2/O2 plasma in capacitively coupled discharge are studied by using a one-dimensional fluid model. Totally, 48 different species (electrons, ions, neutrals, radicals and excited species) are involved in this simulation. Time evolution of the particle densities and electron temperature with different duty cycles are obtained, as well as the electronegativity nSiH−3/ne of the main negative ion (SiH−3). The results show that, by reducing the duty cycle, higher electron temperature and particle density can be achieved for the same average dissipated power, and the ion energy can also be effectively reduced, which will offer evident improvement in plasma deposition processes compared with the case of continuous wave discharge.

The interaction of a charged particle with a nanosphere is studied based on the dielectric response theory. We obtain the analytical expressions of the induced potential and stopping power, as the charged particle moving outside the nanosphere with a constant velocity. From our results, since the spherical shape limitation, the well-known V-shaped wake effect tracing the particle cannot be observed clearly no matter at the nanosphere surface or in the bulk. Besides, we also find that the particle can even gain energy from the electron polarization as the particle moves to the nanosphere at relatively low velocity.

A hybrid model is used to simulate the characteristics of a collisional sheath in a capacitively coupled plasma (CCP) driven by a dual frequency source including a RF and a pulsed current source applied to the same electrode. The hybrid model includes a fluid model used to simulate the characteristics of the collisional sheath, and a Monte-Carlo (MC) method to obtain both ion energy and ion angular distributions (IEDs and IADs) impinging on the substrate. The effects of the low frequency of the pulsed source and the gas pressure on the characteristics of the sheath, as well as the IEDs and IADs, are studied. The results show that the ratio of pulse/RF frequency and the gas pressure are crucial for the characteristics of the sheath and the IEDs. The IADs are significantly more sensitive to the gas pressure.

Non-thermal plasma at atmospheric pressure was explored for the preparation of polysilicon from SiCl4. The power supply sources of positive pulse and alternating current (8 kHz and 100 kHz) were compared for polysilicon preparation. The samples prepared by using the 100 kHz power source were crystalline silicon. The effects of H2 and SiCl4 volume fractions were investigated. The optical emission spectra showed that silicon species played an important role in polysilicon deposition

Capacitively coupled plasmas (CCPs) have been widely used in thin film deposition and etching in a variety of industries such as those of semi-conductor/microelectronics, flat panel displays and solar-cell panels. In all these applications, to produce uniform plasmas over large surface areas is highly desired, as it not only improves the efficiency of manufacturing but also reduces the defects of product. The dual frequency (DF) CCP had been proposed and has indeed been proven to be a rather promising way to achieve this goal with relatively low cost and great ease. During the past decades, significant progresses have been made in understanding and optimizing the DF CCP, and we provide a brief review of its present research status as well as some prospects for its future research.

In order to investigate the mechanism of etching in low pressure radio-frequency (rf) plasmas, we adopt a two-dimensional Monte-Carlo (MC) cellular method to simulate the profile evolution, in which the ion reflection, the ion angular distribution (IAD) etc. are considered. It is found that the phenomenon of microtrenching results from the reflection of particles on the sidewall and the IAD is responsible for round corners at the bottom of the trench. The deeper the trench is, the more easily microtrenching or notching appear. In addition, the neutral particles can destroy the anisotropic etching of the trench and lead to bowling. On the other hand, by means of solving the Laplace equation near and in the trench with an iterative procedure, we obtain a stable or periodic stable electric field biased by a dc or rf source, in which the charging effect on the photoresist sidewall of the trench is considered. It is observed that both the dc and rf biases applied to the substrate can influence the profiles of etching, and the better etching profiles on the sidewall of the trench can be obtained with the rf bias than those with the dc bias.

The behavior of dust particles in capacitively coupled plasmas with annular electrodes is investigated. With the application of modulated signals on the annular electrodes, the periodical potential wells can be produced and it can play an effective role on dust removing. We pay our attention to the relations between the dust removal efficiency and the modulated signals. It is presented that by increasing the applied voltage or the applied frequency on the annular electrodes, the dust removal efficiency increases significantly. It is also shown that with the increase of the dust diameter, the dust removal efficiency decreases.

A one-dimensional fluid model is developed to investigate the behavior of plasma in the afterglow of pulsed voltage modulated SiH 4 /N 2 /NH 3 discharges at radio-frequency (400 kHz), which are used for the deposition of silicon nitride (SiN x ) films. The model incorporates particle balances, electron energy balance, and Poisson's equation, allowing the equations solved self-consistently. The current work is an attempt to understand the effect of duty cycle on the characteristics of silicon nitride (SiN x ) films. Therefore, the influences of duty cycle on the plasma density, electron temperature, and ion energy at the powered electrode were carefully discussed. We find that by decreasing the duty cycle, the negative ions can be able to escape during the off-time, and the positive ion energy is effectively decreased. On the other hand, the positive ion density is slightly decreased.

We use a two-dimensional particle-in-cell simulation to investigate the dynamic polarization and stopping power for an ion beam propagating through a two-component plasma, which is simultaneously irradiated by a strong laser pulse. Compared to the laser-free case, we observe a reduction in the instantaneous stopping power that initially follows the shape of the laser pulse and becomes particularly large as the laser frequency approaches the plasma electron frequency. We attribute this large reduction in the ion stopping power to an increase in plasma temperature due to the energy absorbed in the plasma from the laser pulse through the process of wave heating. In addition, dynamic polarization of the plasma by the ion is found to be strongly modulated by the laser field.

Salidroside, the 8-O-β-D-glucoside of tyrosol, is the main bioactive component of Rhodiola species and is found mainly in the plant roots. It is well known that glucosylation of tyrosol is the final step in the biosynthesis of salidroside; however, the biosynthetic pathway of tyrosol and its regulation are less well understood. A summary of the results of related studies revealed that the precursor of tyrosol might be tyramine, which is synthesized from tyrosine. In this study, a cDNA clone encoding tyrosine decarboxylase (TyrDC) was isolated from Rhodiola sachalinensis A. Bor using rapid amplification of cDNA ends. The resulting cDNA was designated RsTyrDC. RNA gel-blot analysis revealed that the predominant sites of expression in plants are the roots and high levels of transcripts are also found in callus tissue culture. Functional analysis revealed that tyrosine was best substrate of recombinant RsTyrDC. The over-expression of the sense-RsTyrDC resulted in a marked increase of tyrosol and salidroside content, but the levels of tyrosol and salidroside were 274 and 412%, respectively, lower in the antisense-RsTyrDC transformed lines than those in the controls. The data presented here provide in vitro and in vivo evidence that the RsTyrDC can regulate the tyrosol and salidroside biosynthesis, and the RsTyrDC is most likely to have an important function in the initial reaction of the salidroside biosynthesis pathway in R. sachalinensis.

Local measurement of plasma radial uniformity was performed in a dual frequency capacitively coupled argon plasma (DF-CCP) reactor using an optical probe. The optical probe collects the light emission from a small separate volume in plasma, thus enabling to diagnose the plasma uniformity for different experimental parameters. Both the gas pressure and the low-frequency (LF) power have apparent effects on the radial uniformity of argon plasma. With the increase in either pressure or LF power, the emission profiles changed from a bell-shaped to a double-peak distribution. The influence of a fused-silica ring around the electrodes on the plasma uniformity was also studied using the optical probe. Possible reasons that result in nonuniform plasmas in our experiments are discussed.

Since processed substrates usually exhibit nonplanar surface structures in micro-electro-mechanical-systems (MEMS) etching, a two-dimensional (2D) fluid model is developed to simulate the characteristics of the sheath near a conductive substrate with a circular trench, which is placed in an argon discharge powered by a radio-frequency (RF) current source. The model consists of 2D time-dependent fluid equations, the Poisson equation, and a current balance equation that can self-consistently determine the instantaneous voltage on the substrate placed on a powered electrode. The effects of both the aspect ratio (depth/width) and the structure of the trench on the characteristics of the sheath are simulated. The time-averaged potential and electric field in the sheath are calculated and compared for different discharge parameters. The results show that the radial sheath profile is not uniform and always tends to adapt to the contour of the substrate, which is believed to be the moulding effect. Affected by the structure of the substrate surface, the potential and electric field near the inner and outer sidewalls of the trench exhibit obvious non-uniformity, which will inevitably lead to non-uniformity in etching, such as notching. Furthermore, with a fixed amplitude of the RF current source, the potential drops and the sheath thickness decrease with an increase in aspect ratio.

Plasma potential measurements using the conventional Langmuir probe may cause an error due to the space charge effect. To solve the problem, a tube probe is proposed in this study which can minimize the space charge effect by collecting electrons with an orifice instead of the solid surface of the Langmuir probe. The I-V characteristic of the tube probe exhibits a clear turning point, accurately indicating the plasma potential. Comparing with the results of the conventional Langmuir probe, it suggests that the plasma potential measured by the Langmuir probe may be underestimated by about 0.1-0.2 Te/e, which may cause underestimation of the electron density by about 10%-20%. Combination use of the tube probe and the Langmuir probe is suggested for accurate measurement of the electron density.Plasma potential measurements using the conventional Langmuir probe may cause an error due to the space charge effect. To solve the problem, a tube probe is proposed in this study which can minimize the space charge effect by collecting electrons with an orifice instead of the solid surface of the Langmuir probe. The I-V characteristic of the tube probe exhibits a clear turning point, accurately indicating the plasma potential. Comparing with the results of the conventional Langmuir probe, it suggests that the plasma potential measured by the Langmuir probe may be underestimated by about 0.1-0.2 Te/e, which may cause underestimation of the electron density by about 10%-20%. Combination use of the tube probe and the Langmuir probe is suggested for accurate measurement of the electron density.

Two-dimensional electromagnetic particle-in-cell simulations are performed to investigate the transport of relativistic electron beams co-moved with a proton beam in background plasmas. For the beam with the radius much larger than the plasma skin depth, the current filamentation instability excited by the relativistic electron beam can be clearly observed and the transverse magnetic fields in the plasma increase significantly. The proton beam is modulated strongly by the electromagnetic fields in plasmas, and a netlike structure in the beam profile is formed with a high density contrast, which can be provided as an effective tool to diagnose the instability. The dynamic effects of plasma ions are shown to be important and play a significant role in the dynamic evolution of the proton beam.

Considering finite Larmor radius (FLR) effects, wake effects and stopping power induced by proton projectile in two-component magnetized plasma are investigated within a linear response framework. Numerical results show that, FLR lessens wake effects and stopping power, essentially through excitation of collective plasma electron modes.

In plasma enhanced chemical vapor deposition, the substrate placed directly on a metallic electrode, such as an insulator, will often be processed by plasma, while it will also affect the plasma in return. In this paper, the effect of coating the electrode and dielectric ring by a dielectric layer (several mm) on a radio frequency capacitively coupled plasma sustained in a SiH4/N2/O2 gas mixture is investigated by means of a two-dimensional self-consistent fluid model. The simulation results show that the introduction of the dielectric layer on the lower electrode can effectively suppress the edge effect, leading to the radial heterogeneity of the plasma, compared with modulating the pressure and electrode spacing. In addition, considering that the gas-phase deposition precursors have not been well confirmed in the SiH4/N2/O2 gas mixture, we have investigated the nitrogen-, silicon-, and oxygen-containing species as functions of the pressure and composition ratio of the mixed gas. It is found that SiH3O, SiH2O, O, N, and NO may be the most important deposition precursors rather than SiN and HSiNH2. Furthermore, we calculate the deposition rates of Si, O, and N atoms and find that those of Si and O atoms are greatly influenced by the pressure and gas composition ratio. However, the deposition rate of the N atom seems to be not sensitive to the external parameters owing to the fact that two main precursors N and NO of the N atom exhibit opposite trends as the external parameters change.

The large-area capacitive discharges driven at very high frequencies have been attracting much attention due to their wide applications in material etching and thin film deposition. However, in the regime, the standing wave effect (SWE) becomes a major limitation for plasma material processing uniformity. In this work, a fiber Bragg grating sensor was utilized for the observation of the SWE in a large-area capacitive discharge reactor by measuring the radial distribution of the neutral gas temperature T g. The influences of the RF power and the working pressure on the radial profiles of T g were studied. At a higher frequency (100 MHz) and a lower pressure (5 Pa), T g presents a center-peaked radial distribution, indicating a significant SWE. As the RF power increases, the central peak of T g becomes more evident due to the enhanced SWE. By contrast, at 100 MHz and a higher pressure (40 Pa), the radial distribution of T g shows an evident peak at the electrode edge and T g decays dramatically towards the discharge center because the electromagnetic waves are strongly damped as they are propagating from the edge to the center. At a lower frequency (27 MHz), only edge-high profiles of T g are observed for various pressures. For the sake of a comparison, a hairpin resonance probe was used to measure the radial distributions of the plasma density n p under the same condition. The radial profiles of T g are found to generally resemble those of n p under various conditions. Based on the experimental results, the neutral gas heating mechanism was analyzed.

Densities of Ar metastable states 1s5 and 1s3 are measured by using the tunable diode laser absorption spectroscopy (TDLAS) in Ar and Ar/O2 mixture dual-frequency capacitively coupled plasma (DF-CCP). We investigate the effects of high-frequency (HF, 60 MHz) power, low-frequency (LF, 2 MHz) power, and working pressure on the density of Ar metastable states for three different gas components (0%, 5%, and 10% oxygen mixed in argon). The dependence of Ar metastable state density on the oxygen content is also studied at different working pressures. It is found that densities of Ar metastable states in discharges with different gas components exhibit different behaviors as HF power increases. With the increase of HF power, the metastable density increases rapidly at the initial stage, and then tends to be saturated at a higher HF power. With a small fraction (5% or 10%) of oxygen added in argon plasma, a similar change of the Ar metastable density with HF power can be observed, but the metastable density is saturated at a higher HF power than in the pure argon discharge. In the DF-CCP, the metastable density is found to be higher than in a single frequency discharge, and has weak dependence on LF power. As working pressure increases, the metastable state density first increases and then decreases, and the pressure value, at which the density maximum occurs, decreases with oxygen content increasing. Besides, adding a small fraction of oxygen into argon plasma will significantly dwindle the metastable state density as a result of quenching loss by oxygen molecules.

In this paper, the NiCoCrAlY bond-coats was deposited onto the DZ4 nickel-based superalloy substrate by using low-pressure Plasma Spraying (LPPS) process, and then the coats were irradiated by high-current pulsed electron beam (HCPEB). Phase structures and microstructure of the HCPEB-treated NiCoCrAlY coating were analyzed by SEM, XRD and EDAX. The present results showed that the coating surface was remelted after HCPEB treatments, became smooth, had crater eruption, and the coating hadn’t produced distinct residual stresses. The results of the isothermal oxidations experiment performed in 900°C static air revealed that the oxidation resistance of the coating was enhanced obviously after HCPEB-treated and the oxides were mainly Aluminum-oxides, but without HCPEB-treated, the oxides of coating also had Nickel-oxides.

A retarding field energy analyzer (RFEA) is used to measure the time-averaged ion energy distributions (IEDs) on the substrate in both continuous wave (CW) and synchronous pulse modulated radio-frequency (RF) inductively coupled Ar plasmas (ICPs). The effects of the phase shift θ between the RF bias voltage and the RF source on the IED is investigated under various discharge conditions. It is found that as θ increases from 0 to π, the IED moves towards the low-energy side, and its energy width becomes narrower. In order to figure out the physical mechanism, the voltage waveforms on the substrate are also measured. The results show that as θ increases from 0 to π, the amplitude of the voltage waveform decreases and, meanwhile, the average sheath potential decreases as well. Specifically, the potential drop in the sheath on the substrate exhibits a maximum value at the same phase (i.e., θ = 0) and a minimum value at the opposite phase (i.e., θ = π). Therefore, when ions traverse across the sheath region above the substrate, they obtain less energies at lower sheath potential drop, leading to lower ion energy. Besides, as θ increases from π to 2π, the IEDs and their energy widths change reversely.

The characteristics of sheath in a cylindrical Polyethylene terephthalate (PET) film for plasma immersion ion implantation (PIII) have been investigated numerically using a one-dimensional self-consistent fluid model. The time-dependent surface potential and the charge density accumulated on the inner surface of PET-film are obtained. The numerical results demonstrate that the charging effects lead to the reduction of surface potential during pulse on time, the implanted ions thus cannot reach the desirable energy. In order to diminish the influence of charging effects one can shorten the pulse fall time and thin the PET-film.

The surface charging effect in hybrid dc/rf capacitively coupled plasmas is investigated by particle-in-cell/Monte Carlo simulations with an equivalent-circuit module. When the thickness of the dielectric is fixed, the self-bias dc voltage induced by the charge accumulated in the dielectric first increases and then decreases with increased dc voltage. The ratio of electron-to-ion charge flowing into the dielectric increases from −1.195 to −2.582. Increasing the dc voltage results in the number of high-energy ions bombarding the dielectric decreasing. The average electron energy at the dielectric decreases to the minimum value at the biggest self-bias dc voltage in the beginning and then rapidly increases. While fixing the dc source with thickening the dielectric, the self-bias dc voltage rises, but the charge ratio decreases. The average electron energy decreases monotonically and the ion-energy distributions (IEDs) at the dielectric are shifted toward the higher energy region. The results imply that the applied dc voltage may increase the electron flux and average energy to the dielectric at the cost of reduced etching rate, which may mitigate the notching effect. The applied dc voltage can also serve as a tool to modulate the ion IEDs. At the same time, a thicker dielectric will require higher applied dc voltage.

The dependence of the electron density and the emission intensity on external parameters during the transitions of the electron power absorption mode is experimentally studied in asymmetric electropositive (neon) and electronegative (CF4) capacitively coupled radio-frequency plasmas. The spatio-temporal distribution of the emission intensity is measured with phase resolved optical emission spectroscopy and the electron density at the discharge center is measured by utilizing a floating hairpin probe. In neon discharge, the emission intensity increases almost linearly with the rf voltage at all driving frequencies covered here, while the variation of the electron density with the rf voltage behaves differently at different driving frequencies. In particular, the electron density increases linearly with the rf voltage at high driving frequencies, while at low driving frequencies the electron density increases slowly at the low-voltage side and, however, grows rapidly, when the rf voltage is higher than a ce...

The electron characteristics are investigated in 2 MHz and 13.56 MHz inductively coupled hydrogen discharges with an expansion region. The influence of the gas pressure and radio-frequency of the power source on the electron energy probability functions (EEPFs), electron density, and electron temperature at high deposition power has been presented. The measured EEPFs in the driver region of the discharge evolve from a three-temperature Maxwellian distribution to a Maxwellian distribution as the pressure increases. Different characteristic frequencies calculated based on the measured plasma parameters show that stochastic heating of electrons dominates at pressures lower than 0.3 Pa and it has to be considered for pressures lower than 1.0 Pa, while Ohmic heating dominates at higher pressure. Furthermore, the EEPFs as a function of the total energy evolve from the identical shape to discrete shapes with axial position and pressure, indicating a transition of electron kinetics from nonlocal to local regimes....

Radial non-uniformities of dual frequency capacitively coupled argon plasma were experimentally studied, using an optical emission spectroscopy probe, for different discharge pressures, discharge gaps, and frequencies and powers of the low frequency source. It was shown that the plasma emission profiles strongly depend on the working gas pressure and the lower frequency (LF) power. With the increasing LF power the emission profiles changed from a bell-shaped distribution at low LF power to a double-peak distribution at high LF power.

In this paper, we investigate the electronic excitations induced by a charged particle moving outside a nano-dielectric sphere covered with infinitesimally thin metal film by using the linearized quantum hydrodynamic (QHD) theory. General expressions of the induced potential of the electron and the stopping power of the charged particle are derived in spherical coordinates systems. In our calculations, the spherical distribution of the induced potential for different particle speed is examined. The results indicate that an oscillatory wake effect exists in the electron gas during the interactions. In addition, the dependence of the stopping power on a charged particle position and relative permittivity of a dielectric sphere is analyzed.

A kinetic model combined with the dielectric response theory is employed to study the electronic excitation on the nanotube walls during the channeling of protons through double-walled carbon nanotubes. Analytical expressions of the self-energy and stopping power are obtained with protons moving along the axis of the double-walled nanotubes. Calculation results show us interesting double-peak curves of the self-energy and stopping power, under strong influence of the damping factor and the special double-walled nanotube geometry. Relatively increasing the damping factor and the chiral parameter of the outer wall can reduce the interference effects between the two walls and weaken the double-peak to one-peak shapes.

We have developed a full paralleled 2D electrostatic Particle-in-Cell/Monte-Carlo Coupled (PIC-MCC) code for capacitively coupled plasma (CCP) simulations. In this code, we distributed the grid between processors along radial direction, and Poisson equation is solved accordingly paralleled. We applied a couple of numerical accelerating technologies: paralleled fast Poisson solver, assembler pushing code, particle sorting and so on. Theoretical analysis and numerical benchmark showed that this parallel framework had good efficiency and scalability. The framework of the code and the optimization technologies and algorithms are discussed, benchmarks and simulation results are also shown.

A two-dimensional (2D) fluid model is presented to study the discharge of argon in a dual frequency capacitively coupled plasma (CCP) reactor. We are interested in the influence of low-frequency (LF) source parameters such as applied voltage amplitudes and low frequencies on the plasma characteristics. In this paper, the high frequency is set to 60 MHz with voltage 50 V. The simulations were carried out for low frequencies of 1, 2 and 6 MHz with LF voltage 100 V, and for LF voltages of 60, 90 and 120 V with low frequency 2 MHz. The results of 2D distributions of electric field and ion density, the ion flux impinging on the substrate and the ion energy on the powered electrode are shown. As the low frequency increases, two sources become from uncoupling to coupling. When two sources are uncoupling, the increase in LF has little impact on the plasma characteristics, but when two sources are coupling, the increase in LF decreases the uniformities of ion density and ion flux noticeably. It is also found that with the increase in LF voltage, the uniformities in the radial direction of ion density distribution and ion flux at the powered electrode decreases significantly, and the energy of ions bombarding on the powered electrode increases significantly.

Plasma treatment can effectively modify the surface characteristics of fabrics, such as wettability, dyeability and adhesion strength. In this paper, dielectric barrier discharge (DBD) in ambient air is applied to modify linen surface and improve the grafting efficiency and dyeability. Scanning electron microscope (SEM) shows that DBD treatment can effectively change the surface morphology of the treated linen. Raman spectrum, SEM and Fourier transform infrared spectroscopy conform that graft reaction certainly takes place on the DBD-treated linen surface. The dyeability improves with the increase of grafting efficiency, which shows that graft has a great effect on dyeability. For the grafting efficiency and dyeability, the optimal DBD treatment time is 30 s in this experiment. The possible reason may be that, with the increase of the treatment time, the surface degradation will become strong, which will lead to the invalidation of some already modified results.

Electronic excitations induced by a charged particle moving above two-dimensional electron gases are studied by means of the linearized quantum hydrodynamic (QHD) theory. In this calculation, we show that the influence of the quantum effects on the interaction process should be taken into account. The induced potential and the perturbed density of the electron gases as well as the stopping power of the particles are derived as functions of the projectile velocity, the particle position and the density function when including the quantum statistical and quantum diffraction effects. The dependence relations of the induced potential and the particle speed around the peak position at which the stopping power takes the maximum value are also discussed in this work.

To study the cytological and biochemical characteristics of intine, pollen deprived of exine, or de-exined pollen, was isolated from the gymnosperms Pinus bungeana and Picea wilsonii. The factors influencing the isolation rate were examined. Cellulose, callose, pectin, and arabinogalactan proteins (AGPs) were localized in this material using fluorescent probes, and components of the isolated intine were further analyzed by Fourier transform infrared (FTIR) microspectroscopy. The isolation protocol was repeatable and reliable. Cellulose was found to be evenly distributed on the surface of the intine, as indicated by strong calcofluor White ST (CW) fluorescence, and aniline blue staining revealed that callose was present on the intine of P. bungeana but not on that of P. wilsonii. Immunolabeling revealed that acidic pectin epitopes recognized by the monoclonal antibody JIM5 were present on the pollen intine, as well as esterified pectin recognized by the monoclonal antibody JIM7, and AGPs recognized by the LM2 antibody. Two lectin binding sites, the concanavalin agglutinin (Con A) and soybean agglutinin (SBA) binding sites, were present on the intine surface, but no wheat germ agglutinin (WGA) binding sites were detectable. These results were confirmed by FTIR analysis.

Optical emission spectroscopy has been applied to study the spatially resolved measurements of the emission intensities of OH (A(2)Sigma--X(2)Pi, 0-0) and N(2)(+) (B(2)Sigma(u)(+)--X(2)Sigma(g)(+), 0-0, 391.4 nm) produced by a high-voltage positive pulsed streamer discharge consisting of a gas mixture of N(2) and H(2)O in a wire-plate reactor under severe electromagnetic interference at atmospheric pressure. The effects of pulse peak voltage, pulse repetition rate, and the added O(2) flow rate on the spatial distributions of the emission intensity of OH (A(2)Sigma--X(2)Pi, 0-0) and N(2)(+) (B(2)Sigma(u)(+)--X(2)Sigma(g)(+), 0-0, 391.4 nm) in the lengthwise direction (direction from wire to plate) are investigated. It has been found that the emission intensities of OH (A(2)Sigma--X(2)Pi, 0-0) and N(2)(+) (B(2)Sigma(u)(+)--X(2)Sigma(g)(+), 0-0, 391.4 nm) rise with an increase in both pulse peak voltage and pulse repetition rate and decrease with an increase in oxygen flows added in an N(2) and H(2)O gas mixture. The emission intensity of OH (A(2)Sigma--X(2)Pi, 0-0) decreases with increasing the distance from the wire electrode. The emission intensity of N(2)(+) (B(2)Sigma(u)(+)--X(2)Sigma(g)(+), 0-0, 391.4 nm) is nearly constant at 0-4mm from wire electrode, and sharply increases near the ground electrode. The vibrational temperature of N(2) (C) increases with increasing O(2) flows and keeps almost constant in the lengthwise direction under the present experimental conditions. The main physicochemical processes involved are also discussed in this paper.

Conical dc discharge is generated between a copper cathode with a hemispherical head (2-7 mm in diameter) and a static water anode in ambient air. The discharge is hollow and is just like an umbrella if the electrical conductivity of the water electrode is higher than 17.31 musldrcm-1. The profile is composed of three zones with different luminosities. The effects of the discharge current, air gap length, cathode dimension, and electrical conductivity of the water electrode on the discharge are studied. Volt-ampere characteristics and images of the discharge under different experimental conditions are shown to characterize the discharge. A mechanism for stabilizing the discharge is discussed.

The emission spectrum of the molecule OH (A 2 Σ→X 2 Π, 0–0) during a high-voltage, bi-directional pulsed corona discharge consisting of a gas mixture of N 2 and H 2 O in a wire-plate reactor has been successfully recorded under severe electromagnetic interference at atmospheric pressure. The relative vibrational populations and the vibrational temperature of N 2 (C, v ′) have also been determined. Due to the difficulty of determining the exact overlapping spectral line shape function of the OH (A 2 Σ→X 2 Π, 0–0) and the Δ v =+1 vibrational transition band of N 2 (C 3 Π u →B 3 Π g ), a practicable Gaussian form is used for calculating the emission intensity of OH (A 2 Σ→X 2 Π, 0-0) and the Δ v =+1 vibrational transition band of N 2 (C 3 Π u →B 3 Π g ). The emission intensity of OH (A 2 Σ→X 2 Π, 0–0) has been evaluated with a satisfactory accuracy by subtracting the emission intensity of the Δ v =+1 vibrational transition band of N 2 (C 3 Π u →B 3 Π g ) from the overlapping spectra. The relative population of OH (A 2 Σ) has been obtained by the emission intensity of OH (A 2 Σ→X 2 Π, 0–0) and Einstein's transition probability. The influences of peak voltage, pulse repetition rate and O 2 flow rate on the relative population of OH (A 2 Σ) radicals have also been investigated. We found that the relative population of OH (A 2 Σ) rises with an increase in both the peak applied voltage and the pulse repetition rate. When oxygen is added to an N 2 and H 2 O gas mixture, the relative population of OH (A 2 Σ) radicals decreases exponentially with an increase in added oxygen. The main physicochemical processes involved are also discussed in this paper.

Using a one-dimensional self-consistent fluid model, the effect of pulse rise time on charging effects at dielectric surfaces is investigated during plasma immersion ion implantation (PIII) with planar and cylindrical geometries. The numerical results demonstrate that the pulse rise time plays an important role in PIII process with dielectric substrates. It is found that the charge dose accumulated on the dielectric surface is significant as decreasing pulse rise time, and the surface potential decreases at the later stage of the pulse, which results in the lower ion impact energy. On the other hand, the longer pulse rise time would lead to the lower charge dose accumulated on the dielectric surface and higher ion impact energy at the later stage of the pulse, which would elevate the effective implanted dose and introduce the ions to the depth deep enough for surface modification.