The melting, evaporation and oxidation behaviors as well as the solidification phenomena of tungsten and molybdenum in induction plasma were studied. Scanning electron microscopy was used to examine the morphology and...The melting, evaporation and oxidation behaviors as well as the solidification phenomena of tungsten and molybdenum in induction plasma were studied. Scanning electron microscopy was used to examine the morphology and the cross section of plasma-processed powders. X-ray diffraction was used to analyze the oxides formed on the particle surface of these two metals. The influence of spray chamber pressure on the spheroidization and oxidation phenomena was discussed. The results show that fewer Mo particles than W particles are spheroidized at the same powder feed rate under the same plasma spray condition although molybdenum has a lower melting point. A small fraction of tungsten is evaporized and condensed either on the surface of tungsten particles nearby or on the wall of spray chamber. Tungsten oxides were found in tungsten powder processed under soft vacuum condition. Extremely large grains form inside some spheroidized particles of tungsten powder.展开更多
A long-pulse plasma discharge for more than 30 min. was achieved on the Large Helical Device （LHD）. A plasma of ne = 0.8 × 10^19 m^-3 and T10 = 2.0 keV was sustained with PICH = 0.52 MW, PECH = 0.1 MW and avera...A long-pulse plasma discharge for more than 30 min. was achieved on the Large Helical Device （LHD）. A plasma of ne = 0.8 × 10^19 m^-3 and T10 = 2.0 keV was sustained with PICH = 0.52 MW, PECH = 0.1 MW and averaged PNBI = 0.067 MW. Total injected heating energy was 1.3 G J, which was a quarter of the prepared RF heating energy. One of the keys to the success of the experiment was a dispersion of the local plasma heat load to divertors, accomplished by shifting the magnetic axis inward and outward.展开更多
Sintered silicon carbide(SiC)was etched by a dielectric barrier discharge source.A high voltage bipolar pulse was used with helium gas for the plasma generation.One stable filament plasma was generated and could be us...Sintered silicon carbide(SiC)was etched by a dielectric barrier discharge source.A high voltage bipolar pulse was used with helium gas for the plasma generation.One stable filament plasma was generated and could be used for SiC etching.As the processing gas(NF3)mixing rate increased,the width and depth of the etching profile became narrower and deeper.The differentiated V-Q Lissajous method was used for measuring the capacitances(Ceq)of the electrode after the plasma turned on.The width of the etching profile was proportional to Ceq.As the current peak value/smx of the substrate current in creased,the volume removal rate of SiC increased.The etch depth was proportional to the ratio of/smx to Ceq.Additionally,because of the different characteristics of the plasma disks on SiC substrate by the voltage polarity,the etching profile was unstable.However,in high NF3 mixing process,the etching profile became stable and deeper.展开更多
Both direct current dc plasma and radio frequency induction plasma were used to deposit tungsten coatings on copper electrodes. Fine tungsten powder with mean particle size of 5 μm and coarse tungsten powder with par...Both direct current dc plasma and radio frequency induction plasma were used to deposit tungsten coatings on copper electrodes. Fine tungsten powder with mean particle size of 5 μm and coarse tungsten powder with particle size in the range from 45 μm to 75 μm were used as plasma spray feedstock. It is found that dc plasma is only applicable to spray the fine tungsten powder and induction plasma can be used to spray both the coarse powder and the fine powder. The tungsten coating deposited by the induction plasma spraying of the coarse powder is extremely dense. Such a coating with an interlocking structure and an integral interface with the copper substrate demonstrates high cohesion strength and adhesion strength.展开更多
Radio frequency (RF) induction plasma was used to make free-standing deposition of molybdenum (Mo). The phenomena of particle melting, flattening, and stacking were investigated. The effect of process parameters such ...Radio frequency (RF) induction plasma was used to make free-standing deposition of molybdenum (Mo). The phenomena of particle melting, flattening, and stacking were investigated. The effect of process parameters such as plasma power, chamber pressure, and spray distance on the phenomena mentioned above was studied. Scanning electron microscopy (SEM) was used to analyze the plasma-processed powder, splats formed, and deposits obtained. Experimental results show that less Mo particles are spheroidized when compared to the number of spheroidized tungsten (W) particles at the same powder feed rate under the same plasma spray condition. Molten Mo particles can be sufficiently flattened on substrate. The influence of the process parameters on the flattening behavior is not significant. Mo deposit is not as dense as W deposit, due to the splash and low impact of molten Mo particles. Oxidation of the Mo powder with a large particle size is not evident under the low pressure plasma spray.展开更多
In this study, commercial biaxially oriented polypropylene （BOPP）, polyvinyl chlo- ride （PVC） and poly （methyl methacrylate） （PMMA） films were treated with nitrogen plasma over different exposure times in a Py...In this study, commercial biaxially oriented polypropylene （BOPP）, polyvinyl chlo- ride （PVC） and poly （methyl methacrylate） （PMMA） films were treated with nitrogen plasma over different exposure times in a Pyrex tube surrounded by a DC variable magnetic field. The chemi- cal changes that appeared on the surface of the samples were investigated using Fourier transform infrared （FT4R） spectroscopy and attenuated total reflectance Fourier transform infrared （ATR- FTIR） spectroscopy after treatment for 2 min, 4 min and 6 rain in a nitrogen plasma chamber. Effects of the plasma treatment on the surface topographies and contact angles of the untreated and plasma treated films were also analyzed by atomic force microscopy （AFM） and a contact angle measuring system. The results show that the plasma treated films become more hydrophilic with an enhanced wettability due to the formation of some new polar groups on the surface of the treated films. Moreover, at higher exposure times, the total surface energy in all treated films increased while a reduction in contact angle occurred. The behavior of surface roughness in each sample was completely different at higher exposure times.展开更多
In this study atmospheric pressure dielectric barrier discharge （DBD） plasma has been employed for sterilizing dry turmeric powders. A 6 kV, 6 kHz frequency generator was used to generate plasma with Ar, Ar/Ou, He, ...In this study atmospheric pressure dielectric barrier discharge （DBD） plasma has been employed for sterilizing dry turmeric powders. A 6 kV, 6 kHz frequency generator was used to generate plasma with Ar, Ar/Ou, He, and He/O2 gases between the 5 mm gap of two quartz covered electrodes. The complete sterilization time of samples due to plasma treatment was measured. The most important contaminant of turmeric is bacillus subtilis. The results show that the shortest sterilization time of 15 rain is achieved by exposing the samples to Ar/O2 plasma. Survival curves of samples are exponential functions of time and the addition of oxygen to plasma leads to a significant increase of the absolute value of time constant of the curves. Magnitudes of protein and DNA in treated samples were increased to a similar value for all samples. Taste, color, and solubility of samples were not changed after the plasma treatment.展开更多
Microbial contamination induces surface deformations and strength degradation of cotton fabrics by invading deeply into the fibers. In this study, the sterilization effects of low pressure plasmas on bacteria-inoculat...Microbial contamination induces surface deformations and strength degradation of cotton fabrics by invading deeply into the fibers. In this study, the sterilization effects of low pressure plasmas on bacteria-inoculated cotton fabrics were investigated. Oxygen plasma treatment completely sterilized the cotton fabrics inoculated with various concentrations of staphylococcus aureus. Also, the influence of plasma treatment on physical properties of fabrics was examined. It was found that the plasma treatment did not affect ultimate tensile strength and surface morphology of the fabrics because it took advantage of relatively low plasma temperature.展开更多
A novel method capable of sufficient mixing of titanium powder and methane of carbon source was developed in the synthesis of titanium carbide by induction plasma reactive spray. X ray diffraction analysis, optical mi...A novel method capable of sufficient mixing of titanium powder and methane of carbon source was developed in the synthesis of titanium carbide by induction plasma reactive spray. X ray diffraction analysis, optical microscopy, scanning electron microscopy, and microhardness test were used to characterize the spray formed deposit. The experimental results show that both primary carburization of the titanium particles inside the plasma flame and secondary carburization of the growing deposit on high temperature substrate contribute to the forming of titanium carbide. The transitional phase of TiC 1- x has the same crystal structure as TiC, but has a slightly low lattice constant. The deposit consists of fine grain structure and large grain structure. The fine grain structure, harder than large grain structure, shows grain boundary fracture.展开更多
In this research the effects of mordant and plasma sputtering treatments on the crystallinity and morphological properties of wool fabrics were investigated. The felting behavior of the treated samples was also studie...In this research the effects of mordant and plasma sputtering treatments on the crystallinity and morphological properties of wool fabrics were investigated. The felting behavior of the treated samples was also studied. We used madder as a natural dye and copper sulfate as a metal mordant. We also used copper as the electrode material in a DC magnetron plasma sputtering device. The anti-felting properties of the wool samples before and after dying was studied, and it was shown that the shrink resistance and anti-felting behavior of the wool had been significantly improved by the plasma sputtering treatment. In addition, the percentage of crystallinity and the size of the crystals were investigated using an X-ray diffractometer, and a scanning electron microscope was used for morphological analysis. The amount of copper particles on the surface of the mordanted and sputtered fabrics was studied using the energy dispersive X- ray （EDX） method, and the hydrophobic properties of the samples were examined using the water drop test. The results show that with plasma sputtering treatment, the hydrophobic properties of the surface of wool become super hydrophobic.展开更多
Since runaway electrons and magnetohydrodynamics activity can contribute to serious damage and energy losses in tokamaks, the effect of an external electric field on runaway electrons and hard x-ray spectra is investi...Since runaway electrons and magnetohydrodynamics activity can contribute to serious damage and energy losses in tokamaks, the effect of an external electric field on runaway electrons and hard x-ray spectra is investigated. Parameters such as the plasma current, the hard x-ray photons count and the mean energy of runaway electrons are measured. Positive and negative voltages of 300 V are applied at lOms after the plasma initiation （while the plasma is forming）, at 15ms （while the plasma is stable） and at 20ms （while the plasma is fading away） to attain the most effective time of applying the external electric field. The number of hard x-ray photons has the most changes in the range of O-200 keV when the external electric fields are applied. Also in the duration of 20-30ms of plasma the greatest number of hard x-ray spectra is detected. When the external electric fields are applied, the mean energy of runaway electrons reduces significantly, especially at 15 ms （while the plasma is stab/e）.展开更多
A two-point model is used to investigate the characteristics of scrape-off layer(SOL)plasma with the field line tracing method in the experimental advanced superconducting tokamak.The profiles of plasma density,temper...A two-point model is used to investigate the characteristics of scrape-off layer(SOL)plasma with the field line tracing method in the experimental advanced superconducting tokamak.The profiles of plasma density,temperature and particle flux on the divertor target calculated by the model are in reasonable agreement with experimental observation.Moreover,the profiles of plasma parameters on the divertor target strongly depend on the SOL magnetic topology or the equilibrium configuration from the modeling.展开更多
Recent progress in plasma control studies on the improvement of plasma performance in Heliotron J is reviewed. The supersonic molecular beam injection （SMBI） fueling is successfully applied to Heliotron J plasma. A ...Recent progress in plasma control studies on the improvement of plasma performance in Heliotron J is reviewed. The supersonic molecular beam injection （SMBI） fueling is successfully applied to Heliotron J plasma. A supersonic H2-beam is effectively injected to increase fueling efficiency and generate a peaked density profile. Local fueling with a short-pulsed SMBI can increase the core plasma density and avoid the degradation arising from edge cooling. Second harmonic electron cyclotron current drive （ECCD） experiments were conducted by launching a focused Gaussian beam with a parallel refractive index of -0.05 ≤ Nil 〈 0.6. Results show that the electron cyclotron （EC） driven current is determined not only by Nil but also by local magnetic field （B） structure where the EC power is deposited. Detailed analysis of the observed NI and B dependences is in progress with a ray-tracing simulation using the TRAVIS code. Fast ion velocity distribution was investigated using fast protons generated by ion cyclotron resonant frequency （ICRF） minority heating. For the standard configuration in Heliotron J, charge ex- change neutral particle analysis （CX-NPA） measurements show higher effective temperature of fast minority protons in the on-axis resonance case compared to that in the HFS （high field side） off-axis resonance case. However, the increase in bulk ion temperature in the HFS resonance case is larger than that in the on-axis resonance.展开更多
Hydrogen is produced by direct dissociation of water vapor,i.e.,splitting water molecules by the electrons in water plasma at low pressure(<10–50 Torr)using microwave plasma discharge.This condition generates a hi...Hydrogen is produced by direct dissociation of water vapor,i.e.,splitting water molecules by the electrons in water plasma at low pressure(<10–50 Torr)using microwave plasma discharge.This condition generates a high electron temperature,which facilitates the direct dissociation of water molecules.A microwave plasma source is developed,utilizing the magnetron of a microwave oven and a TE10 rectangular waveguide.The quantity of the generated hydrogen is measured using a residual gas analyzer.The electron density and temperature are measured by a Langmuir probe,and the neutral temperature is calculated from the OH line intensity.展开更多
The radial dependence of edge plasma turbulence is investigated in the IR-T1 tokamak.The radial profile of the fluctuation level and spectra are measured using an array of Langmuir probes(rake probe)in the r/a=0.75-1....The radial dependence of edge plasma turbulence is investigated in the IR-T1 tokamak.The radial profile of the fluctuation level and spectra are measured using an array of Langmuir probes(rake probe)in the r/a=0.75-1.2 region.In all radial positions the edge plasma is turbulently unstable,with a broad band fluctuation spectrum in the frequency range f=10-1000 kHz.The relative fluctuation level,as monitored by the ion saturation current J_(+),is always highest near the wall and decreases monotonically toward the plasma center,while the shape of the fluctuation power spectra is almost unchanged.The result of this experiment shows that in contrast to the more inner regions,the plasma near the wall does not simply have a small density fluctuation about a mean,but rather a shredded structure in which one can imagine that discrete shreds of plasma interact with one another rather than with the average background.展开更多
The Landau damping behavior in a cylindrical inhomogeneous warm magnetized plasma waveguide has been studied.The radial inhomogeneity for different characteristic lengths（L0） with strong spatial dispersion has been ...The Landau damping behavior in a cylindrical inhomogeneous warm magnetized plasma waveguide has been studied.The radial inhomogeneity for different characteristic lengths（L0） with strong spatial dispersion has been taken into account.The analyses have been considered for two limits ωce 〈 ωpe and ωce 〉 ωpe. Due to the radial inhomogeneity of the plasma, all essential equations for studying the Landau damping are calculated in the Bessel–Furrier and differential Bessel–Furrier expansions. The dependence of Landau damping on the inhomogeneity, temperature and external magnetic field for electrostatic modes is scrutinized and described in detail through numerical calculations. The associated numerical results are presented and discussed.展开更多
To investigate the interaction of dusty plasma with magnetized plasmas at divertor plasma simulator,radial profiles of plasma density(ne)and electron temperature were measured in terms of plasma discharge currents and...To investigate the interaction of dusty plasma with magnetized plasmas at divertor plasma simulator,radial profiles of plasma density(ne)and electron temperature were measured in terms of plasma discharge currents and magnetic flux intensity by using a fast scanning probes system with triple tips.Dusty plasma with dusts(a generation rate of 3μg s-1 and a size of 1–10μm)was produced via interactions between a high-power laser beam and a full tungsten target.As ne increases,the scale of the effects of dusty plasma injection on magnetized plasmas was decreased.Also,the duration of transient fluctuation was reduced.For numerical estimation of plasma density perturbation due to dusty plasma injection,the result was 10%at a core region of the magnetized plasma with ne of(2–5)×10^11 cm^-3 at steady state condition.展开更多
A novel fitting procedure is proposed for a better determination of H2 rovibrational distribution from the Fulcher-α band spectroscopy. We have recalculated the transition probabilities and the results show that they...A novel fitting procedure is proposed for a better determination of H2 rovibrational distribution from the Fulcher-α band spectroscopy. We have recalculated the transition probabilities and the results show that they deviate from Franck-Condon approximation especially for the non-diagonal transitions. We also calculated the complete sets of vibrationally resolved cross sections for electron impact d3Ⅱu-X3Σg transition based on the semi-classical Gryzinski theory. An example of experimental study confirms that current approach provides a tool for a better diagnostics of H2 rovibrational distribution in electronic ground state.展开更多
Particle melting and substrate temperature are important in controlling deposited density and residual stress in thermal plasma deposition of refractory materials. In this paper, both the heating and cooling behaviour...Particle melting and substrate temperature are important in controlling deposited density and residual stress in thermal plasma deposition of refractory materials. In this paper, both the heating and cooling behaviours of tungsten particles inside a radio frequency inductively coupled plasma （ICP） and the plasma heat flux to the substrate were investigated. The distribution of the plasma-generated heat on device, powder injection probe, deposition chamber, and substrate was determined by measuring the water flow rate and the flow-in and flow-out water temperatures in the four parts. Substrate temperature was measured by a two-colour pyrometer during the ICP deposition of tungsten. Experimental results show that the heat flux to the substrate accounts for about 20% of the total plasma energy, the substrate temperature can reach as high as 2100 K, and the heat loss by radiation is significant in the plasma deposition of tungsten.展开更多
In this study, commercial poly vinyl chloride （PVC） films were treated by oxygen and argon plasmas in a cylindrical glass tube which was surrounded by a DC variable magnetic field, with different sample positions in...In this study, commercial poly vinyl chloride （PVC） films were treated by oxygen and argon plasmas in a cylindrical glass tube which was surrounded by a DC variable magnetic field, with different sample positions in the plasma reactor and also different exposure durations. Effects of the plasma treatment on the hydrophilic properties of the films were studied by mea- suring the water drop contact angle on the surface of the samples. The surface topography of the untreated and plasma treated films was analyzed and compared by atomic force microscopy （AFM）. The optical characteristic changes in treated samples were investigated using reflective spectrophotometry. Also, the chemical changes which appeared on the surface of the samples were investigated using Fourier transform infrared spectroscopy （FTIR）. The results show that the plasma treated PVC becomes more hydrophilic with an enhanced wettability. A sharp de- crease in the water contact angle may also be a consequence of the surface texturization. The aging effect on wettability of the samples was also investigated. The results show that the effect of oxygen plasma on the surface properties of the samples is more pronounced compared with that of argon plasma.展开更多
文摘The melting, evaporation and oxidation behaviors as well as the solidification phenomena of tungsten and molybdenum in induction plasma were studied. Scanning electron microscopy was used to examine the morphology and the cross section of plasma-processed powders. X-ray diffraction was used to analyze the oxides formed on the particle surface of these two metals. The influence of spray chamber pressure on the spheroidization and oxidation phenomena was discussed. The results show that fewer Mo particles than W particles are spheroidized at the same powder feed rate under the same plasma spray condition although molybdenum has a lower melting point. A small fraction of tungsten is evaporized and condensed either on the surface of tungsten particles nearby or on the wall of spray chamber. Tungsten oxides were found in tungsten powder processed under soft vacuum condition. Extremely large grains form inside some spheroidized particles of tungsten powder.
基金supported in part by the JSPS-CAS Core-University Program in the field of Plasma and Nuclear Fusion
文摘A long-pulse plasma discharge for more than 30 min. was achieved on the Large Helical Device （LHD）. A plasma of ne = 0.8 × 10^19 m^-3 and T10 = 2.0 keV was sustained with PICH = 0.52 MW, PECH = 0.1 MW and averaged PNBI = 0.067 MW. Total injected heating energy was 1.3 G J, which was a quarter of the prepared RF heating energy. One of the keys to the success of the experiment was a dispersion of the local plasma heat load to divertors, accomplished by shifting the magnetic axis inward and outward.
文摘Sintered silicon carbide(SiC)was etched by a dielectric barrier discharge source.A high voltage bipolar pulse was used with helium gas for the plasma generation.One stable filament plasma was generated and could be used for SiC etching.As the processing gas(NF3)mixing rate increased,the width and depth of the etching profile became narrower and deeper.The differentiated V-Q Lissajous method was used for measuring the capacitances(Ceq)of the electrode after the plasma turned on.The width of the etching profile was proportional to Ceq.As the current peak value/smx of the substrate current in creased,the volume removal rate of SiC increased.The etch depth was proportional to the ratio of/smx to Ceq.Additionally,because of the different characteristics of the plasma disks on SiC substrate by the voltage polarity,the etching profile was unstable.However,in high NF3 mixing process,the etching profile became stable and deeper.
文摘Both direct current dc plasma and radio frequency induction plasma were used to deposit tungsten coatings on copper electrodes. Fine tungsten powder with mean particle size of 5 μm and coarse tungsten powder with particle size in the range from 45 μm to 75 μm were used as plasma spray feedstock. It is found that dc plasma is only applicable to spray the fine tungsten powder and induction plasma can be used to spray both the coarse powder and the fine powder. The tungsten coating deposited by the induction plasma spraying of the coarse powder is extremely dense. Such a coating with an interlocking structure and an integral interface with the copper substrate demonstrates high cohesion strength and adhesion strength.
文摘Radio frequency (RF) induction plasma was used to make free-standing deposition of molybdenum (Mo). The phenomena of particle melting, flattening, and stacking were investigated. The effect of process parameters such as plasma power, chamber pressure, and spray distance on the phenomena mentioned above was studied. Scanning electron microscopy (SEM) was used to analyze the plasma-processed powder, splats formed, and deposits obtained. Experimental results show that less Mo particles are spheroidized when compared to the number of spheroidized tungsten (W) particles at the same powder feed rate under the same plasma spray condition. Molten Mo particles can be sufficiently flattened on substrate. The influence of the process parameters on the flattening behavior is not significant. Mo deposit is not as dense as W deposit, due to the splash and low impact of molten Mo particles. Oxidation of the Mo powder with a large particle size is not evident under the low pressure plasma spray.
文摘In this study, commercial biaxially oriented polypropylene （BOPP）, polyvinyl chlo- ride （PVC） and poly （methyl methacrylate） （PMMA） films were treated with nitrogen plasma over different exposure times in a Pyrex tube surrounded by a DC variable magnetic field. The chemi- cal changes that appeared on the surface of the samples were investigated using Fourier transform infrared （FT4R） spectroscopy and attenuated total reflectance Fourier transform infrared （ATR- FTIR） spectroscopy after treatment for 2 min, 4 min and 6 rain in a nitrogen plasma chamber. Effects of the plasma treatment on the surface topographies and contact angles of the untreated and plasma treated films were also analyzed by atomic force microscopy （AFM） and a contact angle measuring system. The results show that the plasma treated films become more hydrophilic with an enhanced wettability due to the formation of some new polar groups on the surface of the treated films. Moreover, at higher exposure times, the total surface energy in all treated films increased while a reduction in contact angle occurred. The behavior of surface roughness in each sample was completely different at higher exposure times.
文摘In this study atmospheric pressure dielectric barrier discharge （DBD） plasma has been employed for sterilizing dry turmeric powders. A 6 kV, 6 kHz frequency generator was used to generate plasma with Ar, Ar/Ou, He, and He/O2 gases between the 5 mm gap of two quartz covered electrodes. The complete sterilization time of samples due to plasma treatment was measured. The most important contaminant of turmeric is bacillus subtilis. The results show that the shortest sterilization time of 15 rain is achieved by exposing the samples to Ar/O2 plasma. Survival curves of samples are exponential functions of time and the addition of oxygen to plasma leads to a significant increase of the absolute value of time constant of the curves. Magnitudes of protein and DNA in treated samples were increased to a similar value for all samples. Taste, color, and solubility of samples were not changed after the plasma treatment.
基金Iran National Science Foundation(INSF) for providing grant of members
文摘Microbial contamination induces surface deformations and strength degradation of cotton fabrics by invading deeply into the fibers. In this study, the sterilization effects of low pressure plasmas on bacteria-inoculated cotton fabrics were investigated. Oxygen plasma treatment completely sterilized the cotton fabrics inoculated with various concentrations of staphylococcus aureus. Also, the influence of plasma treatment on physical properties of fabrics was examined. It was found that the plasma treatment did not affect ultimate tensile strength and surface morphology of the fabrics because it took advantage of relatively low plasma temperature.
文摘A novel method capable of sufficient mixing of titanium powder and methane of carbon source was developed in the synthesis of titanium carbide by induction plasma reactive spray. X ray diffraction analysis, optical microscopy, scanning electron microscopy, and microhardness test were used to characterize the spray formed deposit. The experimental results show that both primary carburization of the titanium particles inside the plasma flame and secondary carburization of the growing deposit on high temperature substrate contribute to the forming of titanium carbide. The transitional phase of TiC 1- x has the same crystal structure as TiC, but has a slightly low lattice constant. The deposit consists of fine grain structure and large grain structure. The fine grain structure, harder than large grain structure, shows grain boundary fracture.
文摘In this research the effects of mordant and plasma sputtering treatments on the crystallinity and morphological properties of wool fabrics were investigated. The felting behavior of the treated samples was also studied. We used madder as a natural dye and copper sulfate as a metal mordant. We also used copper as the electrode material in a DC magnetron plasma sputtering device. The anti-felting properties of the wool samples before and after dying was studied, and it was shown that the shrink resistance and anti-felting behavior of the wool had been significantly improved by the plasma sputtering treatment. In addition, the percentage of crystallinity and the size of the crystals were investigated using an X-ray diffractometer, and a scanning electron microscope was used for morphological analysis. The amount of copper particles on the surface of the mordanted and sputtered fabrics was studied using the energy dispersive X- ray （EDX） method, and the hydrophobic properties of the samples were examined using the water drop test. The results show that with plasma sputtering treatment, the hydrophobic properties of the surface of wool become super hydrophobic.
文摘Since runaway electrons and magnetohydrodynamics activity can contribute to serious damage and energy losses in tokamaks, the effect of an external electric field on runaway electrons and hard x-ray spectra is investigated. Parameters such as the plasma current, the hard x-ray photons count and the mean energy of runaway electrons are measured. Positive and negative voltages of 300 V are applied at lOms after the plasma initiation （while the plasma is forming）, at 15ms （while the plasma is stable） and at 20ms （while the plasma is fading away） to attain the most effective time of applying the external electric field. The number of hard x-ray photons has the most changes in the range of O-200 keV when the external electric fields are applied. Also in the duration of 20-30ms of plasma the greatest number of hard x-ray spectra is detected. When the external electric fields are applied, the mean energy of runaway electrons reduces significantly, especially at 15 ms （while the plasma is stab/e）.
基金JSPS-CAS Bilateral Joint Research Projects,‘Control of wall recycling on metallic plasma facing materials in fusion reactor’supported by the NIFS Collaboration Research Program (Nos.NIFS18KNST130 and NIFS20KNST171)supported by ‘PLADy S’,JSPS Core-to-Core Program,A. Advanced Research Networks
文摘A two-point model is used to investigate the characteristics of scrape-off layer(SOL)plasma with the field line tracing method in the experimental advanced superconducting tokamak.The profiles of plasma density,temperature and particle flux on the divertor target calculated by the model are in reasonable agreement with experimental observation.Moreover,the profiles of plasma parameters on the divertor target strongly depend on the SOL magnetic topology or the equilibrium configuration from the modeling.
基金supported by the JSPS-CAS Core University Program in the field of "'Plasma and Nuclear Fusion"the Collaboration Program of the Laboratory for Complex Energy Processes. IAE. Kyoto University. the NIFS Collaborative flesearch Program (NIFS10KUHL030. etc.)+1 种基金the NIFS/NINS project of Formation of International Network for Scientific Collaborationsthe Grant-in-Aid for Sci.Research. MEXT
文摘Recent progress in plasma control studies on the improvement of plasma performance in Heliotron J is reviewed. The supersonic molecular beam injection （SMBI） fueling is successfully applied to Heliotron J plasma. A supersonic H2-beam is effectively injected to increase fueling efficiency and generate a peaked density profile. Local fueling with a short-pulsed SMBI can increase the core plasma density and avoid the degradation arising from edge cooling. Second harmonic electron cyclotron current drive （ECCD） experiments were conducted by launching a focused Gaussian beam with a parallel refractive index of -0.05 ≤ Nil 〈 0.6. Results show that the electron cyclotron （EC） driven current is determined not only by Nil but also by local magnetic field （B） structure where the EC power is deposited. Detailed analysis of the observed NI and B dependences is in progress with a ray-tracing simulation using the TRAVIS code. Fast ion velocity distribution was investigated using fast protons generated by ion cyclotron resonant frequency （ICRF） minority heating. For the standard configuration in Heliotron J, charge ex- change neutral particle analysis （CX-NPA） measurements show higher effective temperature of fast minority protons in the on-axis resonance case compared to that in the HFS （high field side） off-axis resonance case. However, the increase in bulk ion temperature in the HFS resonance case is larger than that in the on-axis resonance.
文摘Hydrogen is produced by direct dissociation of water vapor,i.e.,splitting water molecules by the electrons in water plasma at low pressure(<10–50 Torr)using microwave plasma discharge.This condition generates a high electron temperature,which facilitates the direct dissociation of water molecules.A microwave plasma source is developed,utilizing the magnetron of a microwave oven and a TE10 rectangular waveguide.The quantity of the generated hydrogen is measured using a residual gas analyzer.The electron density and temperature are measured by a Langmuir probe,and the neutral temperature is calculated from the OH line intensity.
文摘The radial dependence of edge plasma turbulence is investigated in the IR-T1 tokamak.The radial profile of the fluctuation level and spectra are measured using an array of Langmuir probes(rake probe)in the r/a=0.75-1.2 region.In all radial positions the edge plasma is turbulently unstable,with a broad band fluctuation spectrum in the frequency range f=10-1000 kHz.The relative fluctuation level,as monitored by the ion saturation current J_(+),is always highest near the wall and decreases monotonically toward the plasma center,while the shape of the fluctuation power spectra is almost unchanged.The result of this experiment shows that in contrast to the more inner regions,the plasma near the wall does not simply have a small density fluctuation about a mean,but rather a shredded structure in which one can imagine that discrete shreds of plasma interact with one another rather than with the average background.
文摘The Landau damping behavior in a cylindrical inhomogeneous warm magnetized plasma waveguide has been studied.The radial inhomogeneity for different characteristic lengths（L0） with strong spatial dispersion has been taken into account.The analyses have been considered for two limits ωce 〈 ωpe and ωce 〉 ωpe. Due to the radial inhomogeneity of the plasma, all essential equations for studying the Landau damping are calculated in the Bessel–Furrier and differential Bessel–Furrier expansions. The dependence of Landau damping on the inhomogeneity, temperature and external magnetic field for electrostatic modes is scrutinized and described in detail through numerical calculations. The associated numerical results are presented and discussed.
基金National R&D Program through the Nation Research Foundation of Korea(NRF)funded by the Ministry of Education(2017R1D1A1B03033076)National R&D Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Science,ICT&Future Planning(2019M1A7A1A03088471).
文摘To investigate the interaction of dusty plasma with magnetized plasmas at divertor plasma simulator,radial profiles of plasma density(ne)and electron temperature were measured in terms of plasma discharge currents and magnetic flux intensity by using a fast scanning probes system with triple tips.Dusty plasma with dusts(a generation rate of 3μg s-1 and a size of 1–10μm)was produced via interactions between a high-power laser beam and a full tungsten target.As ne increases,the scale of the effects of dusty plasma injection on magnetized plasmas was decreased.Also,the duration of transient fluctuation was reduced.For numerical estimation of plasma density perturbation due to dusty plasma injection,the result was 10%at a core region of the magnetized plasma with ne of(2–5)×10^11 cm^-3 at steady state condition.
基金The project supported by the University of Tokyo and partial supported by National Science Foundation of China (grants No.10135020 and 10275067)
文摘A novel fitting procedure is proposed for a better determination of H2 rovibrational distribution from the Fulcher-α band spectroscopy. We have recalculated the transition probabilities and the results show that they deviate from Franck-Condon approximation especially for the non-diagonal transitions. We also calculated the complete sets of vibrationally resolved cross sections for electron impact d3Ⅱu-X3Σg transition based on the semi-classical Gryzinski theory. An example of experimental study confirms that current approach provides a tool for a better diagnostics of H2 rovibrational distribution in electronic ground state.
文摘Particle melting and substrate temperature are important in controlling deposited density and residual stress in thermal plasma deposition of refractory materials. In this paper, both the heating and cooling behaviours of tungsten particles inside a radio frequency inductively coupled plasma （ICP） and the plasma heat flux to the substrate were investigated. The distribution of the plasma-generated heat on device, powder injection probe, deposition chamber, and substrate was determined by measuring the water flow rate and the flow-in and flow-out water temperatures in the four parts. Substrate temperature was measured by a two-colour pyrometer during the ICP deposition of tungsten. Experimental results show that the heat flux to the substrate accounts for about 20% of the total plasma energy, the substrate temperature can reach as high as 2100 K, and the heat loss by radiation is significant in the plasma deposition of tungsten.
文摘In this study, commercial poly vinyl chloride （PVC） films were treated by oxygen and argon plasmas in a cylindrical glass tube which was surrounded by a DC variable magnetic field, with different sample positions in the plasma reactor and also different exposure durations. Effects of the plasma treatment on the hydrophilic properties of the films were studied by mea- suring the water drop contact angle on the surface of the samples. The surface topography of the untreated and plasma treated films was analyzed and compared by atomic force microscopy （AFM）. The optical characteristic changes in treated samples were investigated using reflective spectrophotometry. Also, the chemical changes which appeared on the surface of the samples were investigated using Fourier transform infrared spectroscopy （FTIR）. The results show that the plasma treated PVC becomes more hydrophilic with an enhanced wettability. A sharp de- crease in the water contact angle may also be a consequence of the surface texturization. The aging effect on wettability of the samples was also investigated. The results show that the effect of oxygen plasma on the surface properties of the samples is more pronounced compared with that of argon plasma.
