MHD Effect of Liquid Metal Film Flows as Plasma-Facing Components

Stability of liquid metal film flow under gradient magnetic field is investigated. Three dimensional numerical simulations on magnetohydrodynamics （MHD） effect of free surface film flow were carried out, with emphasis on the film thickness variation and its surface stability. Three different MHD phenomena of film flow were observed in the experiment, namely, retardant, rivulet and flat film flow. From our experiment and numerical simulation it can be concluded that flat film flow is a good choice for plasma-facing components （PFCs）     

Deposition of Diamond-Like Carbon on Inner Surface by Hollow Cathode Discharge简

A cylindrical hollow cathode discharge （HCD） in CH4/Ar gas mixture at pressure of 20-30 Pa was used to deposit diamond-like carbon （DLC） films on the inner surface of a stainless steel tube. The characteristics of the HCD including the voltage-current curves, the plasma im- ages and the optical emission spectrum （OES） were measured in Ar and CHn/Ar mixtures. The properties of DLC films prepared under different conditions were analyzed by means of Raman spectroscopy and scanning electron microscopy （SEM）. The results show that the electron exci- tation temperature of HCD plasma is about 2400 K. DLC films can be deposited on the inner surface of tubes. The ratio of sp3/sp2 bonds decreases with the applied voltage and the deposition time. The optimizing CH4 content was found to be around CH4/Ar =1/5 for good quality of DLC films in the present system.     

Kinetic Monte Carlo Simulation of Deposition of Co Thin Film on Cu（001）

A kinetic Monte Carlo （kMC） simulation is conducted to study the growth of ultrathin film of Co on Cu（001） surface. The many-body, tight-binding potential model is used in the simulation to represent the interatomic potential. The film morphology of heteroepitaxial Co film on a Cu（001） substrate at the transient and final state conditions with various incident energies is simulated. The Co covered area and the thickness of the film growth of the first two layers are investigated. The simulation results show that the incident energy influences the film growth and structure. There exists a transition energy where the interracial roughness is minimum. There are some void regions in the film in the final state, because of the influence of the island growth in the first few layers. In addition, there are deviations from ideal layer-by-layer growth at a coverage from 0 - 2 monolayers （ML）.     

Surface Modification of Polyethylene by Heparin for Improvement of Antithrombogenicity

The purpose of this paper was to enhance blood compatibility of polyethylene （PE） film. PE film pretreated by argon plasma was subjected to ultraviolet （UV） -induced graft polymerization with Acrylic acid（AAc） （AAc-grafted PE films, PE-g-PAAc） without photo-initiator, then heparin was covalently immobilized on the PE surface （PE-g-HPAAc）. The surface properties and microstructure of PE-g-PAAc and PE-g-HPAAc were studied by static contact angle measurement, atomic force microscope （AFM）, X-ray photoelectron spectroscopy （XPS） and Attenuated total reflectance Fourier transfer infrared spectroscopy （ATR-FTIR）. It was confirmed that AAc and heparin were successfully immobilized onto the surface of PE film. Results of platelet adhesion experiments indicated that the antithrombogenicity of the modified PE film was remarkably improved.     

Optical Emission Spectroscopy of Electron Cyclotron Resonance-Plasma Enchanced Metalorganic Chemical Vapor Deposition Process for Deposition of GaN Film

An investigation was made into the nitrogen-trimethylgallium mixed electron cyclotron resonance （ECR） plasma by optical emission spectroscopy （OES）. The ECR plasma enhanced metalorganic chemical vapour deposition technology was adopted to grow GaN film on an α-Al2O3 substrate. X-ray diffraction （XRD） analyses showed that the peak of GaN （0002） was at 20 = 34.48°, being sharper and more intense with the increase in the Ne： trimethylgallium（TMG） flow ratio. The results demonstrate that the electron cyclotron resonance-plasma enchanced met- alorganic chemical vapor deposition （ECR-MOPECVD） technology is evidently advantageous for the deposition of GaN film at a low growth temperature.     

Deposition of SiOx on Metal Surface with a DBD Plasma Gun at Atmospheric Pressure for Corrosion Prevention

In this study, SiOx films were deposited by a dielectric barrier discharge （DBD） plasma gun at an atmospheric pressure. The relationship of the film structures with plasma powers was investigated by Fourier transform infrared spectroscopy （FTIR）, and scanning electron microscope （SEM）. It was shown that an uniform and cross-linking structure film was formed by the DBD gun. As an application, the SiOx films were deposited on a carbon steel surface for the anti-corrosion purpose. The experiment was carried out in a 0.1 M NaCl solution. It was found that a very good anti-corrosive property was obtained, i.e., the corrosion rate was decreased c.a. 15 times in 5% NaCl solution compared to the non-SiOx coated steel, as detected by the potentiodynamic polarization measurement.     

Effect of N2-Gas Partial Pressure on the Structure and Properties of Copper Nitride Films by DC Reactive Magnetron Sputtering

Copper nitride thin films were deposited on glass substrates by reactive direct current （DC） magnetron sputtering at various N2-gas partial pressures and room temperature. Xray diffraction measurements showed that the films were composed of Cu3N crystallites and exhibited a preferential orientation of the [111] direction at a low nitrogen gas （N2） partial pressure. The film growth preferred the [111] and the [100] direction at a high N2 partial pressure. Such preferential film growth is interpreted as being due to the variation in the Copper （Cu） nitrification rate with the N2 pressure. The N2 partial pressure affects not only the crystal structure of the film but also the deposition rate and the resistivity of the Cu3N film. In our experiment, the deposition rate of Cu3N films was 18 nm/min to 30 nm/min and increased with the N2 partial pressure. The resistivity of the Cu3N films increased sharply with the increasing N2 partial pressure. At a low N2 partial pressure, the Cu3N films showed a metallic conduction mechanism through the Cu path, and at a high N2 partial pressure, the conductivity of the Cu3N films showed a semiconductor conduction mechanism.     

Plasma-Etching Enhanced Mechanical Polishing for CVD Diamond Films

Chemically vapor deposited diamond films were etched at different parameters using oxygen plasma produced by a DC （direct current） glow discharge and then polished by a modified mechanical polishing device. Scanning electron microscope, atomic force microscope and Raman spectrometer were used to evaluate the surface states of diamond films before and after polishing. It was found that a moderate plasma etching would produce a lot of etch pits and amorphous carbon on the top surface of diamond film. As a result, the quality and the efficiency of mechanical polishing have been enhanced remarkably.     

Role of Duty Ratio in Diamond Growth by Pulsed DC-Bias Enhanced Hot Filament Chemical Vapour Deposition

In this study, the role of the pulse duty ratio was investigated during the deposition of diamond films in a hot filament chemical vapour deposition reactor with a pulsed-tic biased substrate positively relative to the hot filaments. The voltage-current characteristics showed that the discharge current rose with the increase of biasing voltage, which was modified by the duty ratio. Before deposition, two approaches were adopted for the pre-treatment of the silicon substrates, respectively, and the substrates were scratched by diamond paste or seeded by diamond powders using the so-called ＇soft dry polished＇ technique. Diamond films were deposited under a fixed discharge power by changing the duty ratios. In the first group with scratched substrates, it was found that under a high duty ratio the diamond grew slowly with quite poor nucleation, while in the second case a high duty ratio induced a high deposition rate and good diamond qual- ity. Reactive hydrocarbon species with high energy are essential for the initial nucleation process, which is more effectively achieved at a high biasing voltage in the condition of a low duty ratio. In the film growth process, the large discharge current at a high duty ratio represents an increased concentration of electrons and reactive species as well, promoting the growth of diamond films.     

Structural and Electrical Properties of Sulfur-Doped Diamond Thin Films

We report our observations on the higher carrier mobility and higher conductivity of sulfur-doped n-type diamond thin films synthesized by the hot filament chemical vapor deposi- tion （HFCVD）. The structural and electrical characterizations of the films are measured by X-ray diffraction （XRD）, Raman spectroscopy, scanning electron microscope （SEM）, energy dispersion X-ray spectra （EDX）, and Hall effect measurements. It is found that the sulfur atoms are in- corporated into the polycrystalline diamond films. The n-type conductivity of the films increases with the H2S concentration, and a conductivity of the films as high as 1.82 ~-l.cm-1 is achieved. The results show that the sulfur atom plays an important role in the structural and electrical properties of sulfur-doped diamond thin films.     

Research on a Folded Blumlein Line Using Kapton Film as Dielectrics

In this project, a Blumlein line with a folded parallel-plates configuration using Kapton film as dielectrics was investigated. The characteristic parameters of this Blumlein line were analysed theoretically. The electric field distributions under different inner radii of the folded part were simulated. The output waveforms on the match load were also simulated by means of an equivalent electric circuit. According to the results of the theoretecal analysis and simulation, a Blumlein line with the folded parallel-plates configuration with an output voltage of 500 kV, a pulse duration of 100 ns, and a characteristic impedance of 4.773Ω was designed and manufactured. The experimental results properly demonstrated the wave transmitting process in the Blumlein line, and provided the voltage waveform of 500 kV and the current waveform of 50 kA with a pulse duration of 150 ns. Some engineering problems such as the edge electric breakdown and measuring precision by a resistance divider were revealed, which must be solved in future work to produce a more compact transmission line.     

Development of Data Acquisition Card Driver for ICRH System on EAST

Presented in this paper is the development of the driver for the data acquisition card with a peripheral component interconnection （PCI） local bus on the ion cyclotron range of frequency heating （1CRH） system. The driver is mainly aimed at the embedded VxWorks system （real-time operating system） which is widely used in various fields of real-time systems. An efficient way is employed to develop this driver, which will advance the real-time control of the ICRH system on the experimental advanced superconductor tokamak （EAST）. The driver is designed using the TORNADO integrated development environment （IDE）, and implemented in C plus language. The details include the hardware configuration, analogue/digital （A/D） and digital/analogue （D/A） conversion, input and output （I/O） operation of the driver to support over five cards. The data acquisition card can be manipulated in a low-level program and meet the requirements of A/D conversion and D/A outputs.     

Effect of Cold Plasma Treatment on Seed Germination and Growth of Wheat简

This study investigated the effect of cold helium plasma treatment on seed germina- tion, growth and yield of wheat. The effects of different power of cold plasma on the germination of treated wheat seeds were studied. We found that the treatment of 80 W could significantly improve seed germination potential （6.0%） and germination rate （6.7%） compared to the control group. Field experiments were carried out for wheat seeds treated with 80 W cold plasma. Com- pared with the control, plant height （20.3%）, root length （9.0%） and fresh weight （21.8%） were improved significantly at seedling stage. At booting stage, plant height, root length, fresh weight, stem diameter, leaf area and leaf thickness of the treated plant were respectively increased by 21.8%, 11.0%, 7.0%, 9.0%, 13.0% and 25.5%. At the same time, the chlorophyll content （9.8%）, nitrogen （10.0%） and moisture content （10.0%） were higher than those of the control, indicating that cold plasma treatment could promote the growth of wheat. The yield of treated wheat was 7.55 t-ha-1, 5.89% more than that of the control. Therefore, our results show that cold plasma has important application prospects for increasing wheat yield.     

Role of Ion Beam Irradiation and Annealing Effect on the Deposition of AlON Nanolayers by Using Plasma Focus Device

AlON nanolayers are synthesized on Al substrate by the irradiation of energetic nitrogen ions using plasma focusing. Samples are exposed to multiple （5, 10, 15, 20 and 25） focus shots. Ion energy and ion number density range from 80 keV to 1.4 MeV and 5.6×10^19 m^- 3 to 1.3×10^19 m ^-3, respectively. Moreover, the effect of continuous annealing （473 K and 523 K） on an AlN surface layer synthesized with 25 focus shots is also examined. The main features of the X-ray diffraction （XRD） patterns with increasing focus shots are： （i） variation in the crystallinity of AlN along （111）, （200） and （311） planes, （ii） increasing average crystallite size of AlN （111） plane, and （iii） stress relaxation observed in AlN （111） and （200） planes. The crystallinity of AlN surface layer is comparatively better at 473 K annealing temperature. A broadened diffraction peak related to an aluminium oxide phase showing weak crystallinity is observed for 15 focus shots while non-bounded oxides are present in all other deposited layers. Raman and Fourier transform infrared spectroscopy （FTIR） analysis confirm the presence of AlN and Al203 for the surface layer annealed at 473 K temperature. Raman analysis shows that the overlapping of AlN and Al2Oa results in the development of residual stresses. Scanning electron microscope （SEM） results demonstrate that the formation of rounded grains （range from 20 nm to 200 nm） and variations in their microstructures features depend on the increasing number of focus shots. Decomposition of larger clusters into smaller ones is observed.     

Simulation of Electron-Beam Generating Plasma at Atmospheric Pressure

As electron-beam generating plasma is widely applied, the software tool EGS4 （Electron-Gamma Shower） was used to simulate the transmission and energy deposition of electron-beam in air. The simulation results indicated that the range of the electron-beam was inversely proportional to the gas pressure in a wide range of gas pressure, and the electron-beam of 200 keV could generate a plasma with a density 10^11 cm^-3 in air of latm. In addition, the energy distribution of the beam-electron and plasma density profile produced by the beam were achieved.     

Density and temperature of fermions and bosons from quantum fluctuations

A novel method to determine the density and temperature of a system constituted by fermions and/or bosons is proposed based on quantum fluctuations. For fermions system, the results in the limit where the reached temperature T is small and where there is no constraint for the reached temperature T compared to the Fermi energy ~f at a given density p are given, respectively. Quadrupole and multiplicity fluctuation relations are derived in terms of T/6f. We compared the two set results in the limit when Tis much smaller compared to Fermi energy Cf and they are consistent, as expected. The classical limit is also obtained for high temperatures and low densities. For bosons system, quadrupole and multiplicity fluctuations using Landau＇s theory of fluctuations near the critical point for a Bose-Einstein condensate （BEC） at a given density p are derived. As an example, we apply our approach to heavy ion collisions using the Constrained Molecular Dynamics model （CoMD） which includes the fermionic statistics. The multiplicity fluctuation quenching for fermions is found in the model and confirmed by experimental data. To reproduce the available experimental data better, we propose a modification of the collision term in the approach to include the possibility of ct-a collisions. The relevant Bose-Einstein factor in the collision term is properly taken into account. This approach increases the yields of bosons relative to fermions closer to data. Boson fluctuations become larger than one as expected.     

Simultaneous Oxidization of NOx and SO2 by a New Non-thermal Plasma Reactor Enhanced by Catalyst and Additive

The non-thermal plasma as one of the most promising technologies for removing NOx and SO2 has attrm~ted much attention. In this study, a new plasma reactor combined with catalyst and additive was developed to effectively oxidize and remove NOx and SO2 in the flue gas. The experimental results showed that TiO2 could improve the oxidation efficiency of SO2 in the case of applying plasma while having a negative effect on the oxidation process of NO and NOx. With the addition of NH3, the oxidation rates of NOx, NO and SO2 were slightly increased. However, the effect of adding NH3 on NOx oxidation was negative when the temperature was above 200℃.     

Mechanical Properties of Thermoplastic Polyurethanes Laminated Glass Treated by Acid Etching Combined with Cold Plasma

To overcome the problem of interlaminar delamination of thermoplastic polyurethane laminated glass, silicate glass was etched with hydrofluoric acid and thermoplastic polyurethane was then treated with cold plasma. Compared with the untreated samples, the interlaminar shear strength of acid etching samples, cold plasma-treated samples and acid etching combined with cold plasma-treated samples increased by 97%, 84% and 341%, respectively. Acid etching combined with cold plasma-treated samples exhibited a higher flexural strength and strain as compared with the untreated samples. The impact energy of acid etching samples, cold plasmatreated samples and acid etching combined with cold plasma-treated samples increased by 8.7%, 8.1% and 11.6%, respectively, in comparison with the untreated samples. FT-IR analysis showed that a large number of -C-O, CO N and CO O C groups appeared on the surface of cold plasma-treated thermoplastic polyurethane, which resulted in the formation of hydrogen bonds. SEM results showed that some pittings formed on the surface of the silicate glass treated by acid etching, which resulted in the formation of a three-dimensional interface structure between tile silicate glass and polyurethane. Hydrogen bonds combined with the three-dimensional interface between silicate glass and polyurethanes co-improved the mechanical properties of thermoplastic polyurethanes laminated glass.     

Simulation and calibration of the response function of multi-sphere neutron spectrometer

In order to realize the on-line real-time measurement of neutron specmnn of ITER fusion, this paper presents a multi-sphere spectrometer system which consists of eight thermal neutron detectors, namely SP9 3He proportional counter, embedded in eight different diameter polyethylene spheres. The response function of eight polyethylene spheres of rnulti-sphere neutron spectrometer was calculated after the simulation of the neutron transport processes in multi-sphere spectrometer by adopting software Geant4. The peak of the response function is in the low energy region for smaller diameter polyethylene sphere. As the polyethylene sphere diameter increased, the peak of the response function moves to the high energy region. The experimental calibration adopts 241Am-Be neutron source. The relative error between normalized data of experiment 47t solid angle counts and normalized data of simulated detection efficiency of 4in to 8in polyethylene sphere is from 1.152% to 12.222%.The experimental results verify the response function of the simulation. All these results provide a theoretical and experimental basis for solving the on-line real-time neutron spectrum of ITER fusion.     

Study of Plume Characteristics of a Stationary Plasma Thruster

Electron density and temperature of the plume are measured by a double Langmuir probe in an experimental chamber. A numerical model based on both particle-in-cell scheme and direct simulation Monte Carlo hybrid method is developed to simulate the flow field of plume. The equation for plasma potential is solved by alternative direction implicit technique. The simulation is verified by comparing the computational results with the measured data. The study indicates that the electron temperature of flow field is about 2 eV and the electron density is about 2.5 ×10^16 - 5×10^15 m^-3 at the central line with a distance of 0.3 - 1.0 m downstream of the thruster exit. The model can well predict the flow field parameters of the steady plume. The efforts of this paper are referable for further investigation.