The ion density distribution in the reaction chamber was diagnosed by a Langmuir probe. The rules of the ion density distribution were obtained under the pressures of 9 Pa, 13 Pa, 27 Pa and 53 Pa in the reaction chamb...The ion density distribution in the reaction chamber was diagnosed by a Langmuir probe. The rules of the ion density distribution were obtained under the pressures of 9 Pa, 13 Pa, 27 Pa and 53 Pa in the reaction chamber, different radio-frequency powers and different positions. The result indicates that the ion density decreases as the pressure increases, and increases as the power decreases. The ion density of axial position z =0 achieves 5.8×1010 on the center of coil under the power of 200 w and pressure of 9 Pa in the reaction chamber.展开更多
Diagnosis of the particle number density of plasma plays an important role in the understanding of plasma sources and processing.Regular radiation signals from plasma oscillation in filaments of atmospheric nitrogen d...Diagnosis of the particle number density of plasma plays an important role in the understanding of plasma sources and processing.Regular radiation signals from plasma oscillation in filaments of atmospheric nitrogen discharge,which were excited by the injection of secondary electron beams during the propagation of the streamer,are employed to determine the ion density of plasma and its evolution in the filaments.Results show that the density of N4＋ in a filament of atmospheric nitrogen discharge is of the order of 1013 cm-3.It is also found that the recombination processes play a dominant role in plasma decay,and that the ion density decreases non-monotonically with time during streamer propagation.展开更多
Neon glow discharge cleaning was firstly attempted in Large Helical Device(LHD) instead of He glow discharge to remove hydrogen neutrals and to control the ion density, n_i.The Ne glow discharge continued for 8 hours ...Neon glow discharge cleaning was firstly attempted in Large Helical Device(LHD) instead of He glow discharge to remove hydrogen neutrals and to control the ion density, n_i.The Ne glow discharge continued for 8 hours overnight after a three-day experiment. At the secondnight H_α emission became weaker than the emission usually observed in the He glow discharge. Aclear reduction of the hydrogen influx was also observed in neutral beam injection (NBI) dischargeswith Ne puff, whereas the neon recycling was strongly enhanced with appearance of a flat densityprofile. As a result, the lowest density limit was further reduced down to 0.2 X 10^(13)cm^(-3). Theuse of Ar puff formed a peaked density profile with a high T_i of 7 keV.展开更多
Aim To investigate the influence of ion density( n i) on the deposition of wurtzite GaN films on the substrate of α Al 2O 3(0001) by electron cyclotron resonance plasma. Methods Langmuir probe measure...Aim To investigate the influence of ion density( n i) on the deposition of wurtzite GaN films on the substrate of α Al 2O 3(0001) by electron cyclotron resonance plasma. Methods Langmuir probe measurement, Double crystal X ray diffraction and Hall measurement were used. Results The quality of GaN film strongly depended on its growth condition. The higher ion density resulted in a higher amount ratio of N/Ga and a lower background electron concentration of GaN film. When the GaN was prepared in the ion density of 2 0×10 11 cm -3 , the amount ratio of N/Ga was close to 1, the electron background density was 3 7×10 18 cm -3 and its full width at half magnitude(FWHM) was 16?arcmin. Conclusion The quality of GaN film can be improved by raising the plasma density.展开更多
The effect of ion current density of argon plasma on target sputtering in magnetron sputtering process was investigated. Using home-made ion probe with computer-based data acquisition system, the ion current density a...The effect of ion current density of argon plasma on target sputtering in magnetron sputtering process was investigated. Using home-made ion probe with computer-based data acquisition system, the ion current density as functions of discharge power, gas pressure and positions was measured. A double-hump shape was found in ion current density curve after the analysis of the effects of power and pressure. The data demonstrate that ion current density increases with the increase in gas pressure in spite of slightly at the double-hump site, sharply at wave-trough and side positions. Simultaneously, the ion current density increases upon increase in power. Es- pecially, the ion current density steeply increases at the double-hump site. The highest energy of the secondary electrons arising from Larmor precession was found at the double-hump position, which results in high ion density. The target was etched seriously at the double-hump position due to the high ion density there. The data indicates that the increase in power can lead to a high sputtering speed rate.展开更多
The layered Li2MnO3 is investigated by using the first-principles calculations within the GGA and GGA-t-U scheme, respectively. Within the GGA4-U approach, the calculated intercalation voltage （ranges from 4,5 V to 4...The layered Li2MnO3 is investigated by using the first-principles calculations within the GGA and GGA-t-U scheme, respectively. Within the GGA4-U approach, the calculated intercalation voltage （ranges from 4,5 V to 4.9 V） is found to be in good agreement with experiments. From the analysis of electronic structure, the pure phase Li2MnO3 is insulating, which is indicative of poor electronic-conduction properties. However, further studies of lithium ion diffusion in bulk Li2MnO3 show that unlike the two-dimensional diffusion pathways in rock salt structure layered cathode materials, lithium can diffuse in a three-dimensional pathway in Li2MnO3, with moderate lithium migration energy barrier ranges from 0.57 to 0.63 e V.展开更多
The in-situ measurements of the ionospheric plasma that we use come from two instruments of the scientific payload of the satellite DEMETER; the plasma analyser IAP （Instrument d＇analyse du plasma） and the Langmuir...The in-situ measurements of the ionospheric plasma that we use come from two instruments of the scientific payload of the satellite DEMETER; the plasma analyser IAP （Instrument d＇analyse du plasma） and the Langmuir probe ISL （Instrument Sonde de Langmuir）. DEMETER is a micro-satellite realized by the CNES（Centre National d＇Etudes Spatiales, France） with a principal objective to seek a possible influence of the seismic activity on the electromagnetic waves in the ionosphere and on the ionospheric plasma. The satellite was placed on June 29, 2004, in a circular and quasi helio-synchronous orbit at -710 km altitude. The experiments function primarily at mid-latitudes （from ＋60° to -60°）. The IAP data were analysed to deduce the ion population （densities of the dominant ions, i.e. generally O^＋, H^＋ and He^＋） therefore the total ion density. The use of data IAP thus requires some precaution to make sure that the electric equilibrium conditions of the satellite, such as the satellite potential （Фsat）, are obtained during the treatment of routine, does not induce an error of measurement. When this potential is negative, the minority light ions H^＋ and He^＋ can be measured in a reliable way when their proportion is above 3% to 5% of that of O^＋. The critical limitation is： under certain conditions, the satellite potential becomes positive and reach a value about -0.5 V so that it becomes impossible to measure H^＋ ions. This is likely to involve a significant error on the composition and the density of the plasma. Therefore we carried out a calibration to estimate the missing density. The ISL experiment （Langmuir probe） provided the collected current/polarized tension characteristics of a cylindrical probe from which both electron density Ne and temperature Te were obtained. In some situations it is necessary to examine the accuracy of the electron density using another technique, for instance the high frequency （HF） spectrogram, provided by ICE （instrument champ electrique） instrument. This technique could give precise information about the accuracy of the data provided by the plasma analyser and the Langmuir probes. The observed satellite surface potential was found to be remarkable and subject of question. It displayed negative values at daytime and positive at night.展开更多
The K-V beam through an axisymmetric uniform-focusing channel is studied using the particle-core model. The beam halo-chaos is found, and a sample function controller is proposed based on mechanism of halo formation a...The K-V beam through an axisymmetric uniform-focusing channel is studied using the particle-core model. The beam halo-chaos is found, and a sample function controller is proposed based on mechanism of halo formation and strategy of controlling halo-chaos. We perform multiparticle simulation to control the halo by using the sample function controller. The numerical results show that our control method is effective. We also find that the radial ion density changes when the ion beam is in the channel： not only can the halo-chaos and its regeneration be eliminated by using the sample function control method, but also the density uniformity can be found at the beam＇s centre as long as an appropriate control method is chosen.展开更多
A high-flux linear plasma device in Sichuan University plasma-surface interaction（SCU-PSI）based on a cascaded arc source has been established to simulate the interactions between helium and hydrogen plasma with the ...A high-flux linear plasma device in Sichuan University plasma-surface interaction（SCU-PSI）based on a cascaded arc source has been established to simulate the interactions between helium and hydrogen plasma with the plasma-facing components in fusion reactors.In this paper,the helium plasma has been characterized by a double-pin Langmuir probe.The results show that the stable helium plasma beam with a diameter of 26 mm was constrained very well at a magnetic field strength of 0.3 T.The core density and ion flux of helium plasma have a strong dependence on the applied current,magnetic field strength and gas flow rate.It could reach an electron density of1.2×10^19m^-3and helium ion flux of 3.2×10^22m^-2s^-1,with a gas flow rate of 4 standard liter per minute,magnetic field strength of 0.2 T and input power of 11 k W.With the addition of-80 Vapplied to the target to increase the helium ion energy and the exposure time of 2 h,the flat top temperature reached about 530°C.The different sizes of nanostructured fuzz on irradiated tungsten and molybdenum samples surfaces under the bombardment of helium ions were observed by scanning electron microscopy.These results measured in the SCU-PSI linear device provide a reference for International Thermonuclear Experimental Reactor related PSI research.展开更多
Aluminum doped zinc oxide （AZO） thin films were prepared by DC magnetron sputtering at low substrate temperature. A coaxial solenoid coil was placed near the magnetron target to enhance the plasma density （Ji）. Th...Aluminum doped zinc oxide （AZO） thin films were prepared by DC magnetron sputtering at low substrate temperature. A coaxial solenoid coil was placed near the magnetron target to enhance the plasma density （Ji）. The enhanced plasma density improved significantly the bulk resistivity （p） and its homogeneity in spatial distribution of AZO films. X-ray diffraction （XRD） analysis revealed that the increased Ji had influenced the crystallinity, stress relaxation and other material properties. The AZO films deposited in low plasma density （LPD） mode showed marked variation in p （ranging from -6.5x10-2 to 1.9x10-3 Ω.cm）, whereas those deposited in high plasma density （HPD） mode showed a better homogeneity of films resistivity （ranging from ~1.3x10-3 to 3.3x10-3 ~.cm） at different substrate positions. The average visible transmittance in the wavelength range of 500-800 nm was over 80%, irrespective of the deposition conditions. The atomic force microscopy （AFM） surface morphology showed that AZO films deposited in HPD mode were smoother than that in LPD mode. The high plasma density produced by the coaxial solenoid coil improved the electrical property, surface morphology and the homogeneity in spatial distribution of AZO films deposited at low substrate temperature.展开更多
An experimental investigation of the saturation ion current densities （Jions） in hydrogen inductively coupled plasma （ICP） produced by a large-power （2-32 kW） radio frequency （RF） generator is reported, then s...An experimental investigation of the saturation ion current densities （Jions） in hydrogen inductively coupled plasma （ICP） produced by a large-power （2-32 kW） radio frequency （RF） generator is reported, then some reasonable explanations are given out. With the increase of RF power, the experimental results show three stages： in the first stage （2-14 kW）, the electron temperature will rise with the increase of RF power in the ICP, thus, the Jions increases continually as the electron temperature rises in the ICP. In the second stage （14 20 kW）, as some H- ions lead to the mutual neutralization （MN）, the slope of Jio^s variation firstly decreases then increases. In the third stage （20-32 kW）, both the electronic detachment （ED） and the associative detachment （AD） in the ICP result in the destruction of H- ions, therefore, the increased amplitude of the Jions in the third stage is weaker than the one in the first stage. In addition, with the equivalent transformer model, we successfully Explain that the Jions at different radial locations in ICP has the same rule. Finally, it is found that the Jions has nothing to do with the outer/inner puffing gas pressure ratio, which is attributed to the high-speed movement of hydrogen molecules.展开更多
Corona discharge suppression for high-voltage direct-current(HVDC)transmission lines at line terminals such as converter stations is a subject that requires attention.In this paper,a method based on a conductor covere...Corona discharge suppression for high-voltage direct-current(HVDC)transmission lines at line terminals such as converter stations is a subject that requires attention.In this paper,a method based on a conductor covered with dielectric film is proposed and implemented through a bench-scale setup.Compared with the bare conductor,the corona discharge suppression effect of the dielectric-film-covered conductor under positive polarity is studied from the composite field strength and ion current density using a line-plate experimental device.The influences of film thickness and film material on the corona discharge suppression effect are investigated.The charge accumulation and dissipation characteristics of different film materials are also studied.The results show that the conductor covered with dielectric film has excellent ability to inhibit corona discharge.The ground-level composite field strength of the conductor covered with dielectric film is lower than its nominal field strength,and its ion current density is at the nA m^(−2) level.The corona threshold voltage can be promoted by increasing the film thickness,but the ability to inhibit corona discharge becomes weak.The larger the surface electric field strength,the more charge accumulated,but the faster the charge dissipation rate.Compared with polyvinyl chloride film,cross-linked polyethylene film has stronger charge accumulation ability and slower charge dissipation rate,which can better restrain the corona discharge of HVDC transmission lines.展开更多
Hybrid ion capacitors have been considered as a very attractive energy source with high energy density and power density since it combines both merits of lithium ion batteries and supercapacitors. However,their commer...Hybrid ion capacitors have been considered as a very attractive energy source with high energy density and power density since it combines both merits of lithium ion batteries and supercapacitors. However,their commercial application has been limited by the mismatch of charge-storage capacity and electrode kinetics between the capacitor-type cathode and battery-type anode. Herein, B and N dual-doped 3D superstructure carbon cathode is prepared through a facile template method. It delivers a high specific capacity, excellent rate capability and good cycling stability due to the B, N dual-doping, which has a profound effect in control the porosity, functional groups, and electronic conductivity for the carbon cathode. The hybrid ion capacitors using B, N dual-doping carbon cathode and prelithiated graphite anode show a high energy density of 115.5 Wh/kg at 250 W/kg and remain about 53.6 Wh/kg even at a high power density of 10 kW/kg. Additionally, the novel hybrid device achieves 76.3% capacity retention after 2000 cycles tested at 1250 W/kg power density. Significantly, the simultaneous manipulation of heteroatoms in carbon materials provides new opportunities to boost the energy and power density for hybrid ion capacitors.展开更多
Ischemic postconditioning renders brain tissue tolerant to brain ischemia,thereby alleviating ischemic brain injury.However,the exact mechanism of action is still unclear.In this study,a rat model of global brain isch...Ischemic postconditioning renders brain tissue tolerant to brain ischemia,thereby alleviating ischemic brain injury.However,the exact mechanism of action is still unclear.In this study,a rat model of global brain ischemia was subjected to ischemic postconditioning treatment using the vessel occlusion method.After 2 hours of ischemia,the bilateral common carotid arteries were blocked immediately for 10 seconds and then perfused for 10 seconds.This procedure was repeated six times.Ischemic postconditioning was found to mitigate hippocampal CA1 neuronal damage in rats with brain ischemia,and up-regulate acid-sensing ion channel 2a expression at the m RNA and protein level.These findings suggest that ischemic postconditioning up-regulates acid-sensing ion channel 2a expression in the rat hippocampus after global brain ischemia,which promotes neuronal tolerance to ischemic brain injury.展开更多
The article theoretically studied the charge-exchange effects on space charge limitedelectron and ion current densities of non-relativistic one-dimensional slab ion diode, and comparedwith those of without charge exch...The article theoretically studied the charge-exchange effects on space charge limitedelectron and ion current densities of non-relativistic one-dimensional slab ion diode, and comparedwith those of without charge exchange.展开更多
A mini-type of plasma source was studied experimentally. The results showed that the plasma density, which was generated by an atmospheric non-equilibrium plasma source, rises with the increase in driving electric-fie...A mini-type of plasma source was studied experimentally. The results showed that the plasma density, which was generated by an atmospheric non-equilibrium plasma source, rises with the increase in driving electric-field and the momentum of gas particles. For a driving electricfield of 56 kV/cm and a gas particles＇ momentum of 10^9 × 10^-22 g·m/s, the ion density can exceed 10^10/cm^3 while the effective volume of the plasma source is only 2.5 cm^2. This study may help develop a method to generate a minitype plasma source with low energy consumption but high ion concentration. This source can be used in chemical industry, environmental engineering and military applications.展开更多
A spark generator was employed to assist surface barrier discharge （SBD） in nitrogen at atmospheric pressure. The influence of spark discharge on the SBD electrical behavior is investigated by means of volt-ampere c...A spark generator was employed to assist surface barrier discharge （SBD） in nitrogen at atmospheric pressure. The influence of spark discharge on the SBD electrical behavior is investigated by means of volt-ampere characteristics. Also, the electron density of plasma in the filament of each SBD arrangement is determined by plasma radiation method. It is found that the filaments in spark-assistant SBD are much stronger, while the corresponding mean electron density is much lower. Results show that the spark generator can improve the uniformity of SBD in atmospheric nitrogen in a particular range of applied frequency.展开更多
We study an intense beam propagating through the double periodic focusing channel by the particle-coremodel,and obtain the beam envelope equation.According to the Poincare-Lyapunov theorem,we analyze the stabilityof b...We study an intense beam propagating through the double periodic focusing channel by the particle-coremodel,and obtain the beam envelope equation.According to the Poincare-Lyapunov theorem,we analyze the stabilityof beam envelope equation and find the beam halo.The soliton control method for controlling the beam halo-chaos isput forward based on mechanism of halo formation and strategy of controlling beam halo-chaos,and we also prove thevalidity of the control method,and furthermore,the feasible experimental project is given.We perform multiparticlesimulation to control the halo by using the soliton controller.It is shown that our control method is effective.We alsofind the radial ion density changes when the ion beam is in the channel,not only the halo-chaos and its regeneration canbe eliminated by using the nonlinear control method,but also the density uniformity can be found at beam's centre aslong as an appropriate control method is chosen.展开更多
A novel technique to generate high-density plasma-called inductively coupled plasma （ICP）, enhanced capacitively coupled plasma （CCP）- is successfully developed. The plasma can be generated using different frequen...A novel technique to generate high-density plasma-called inductively coupled plasma （ICP）, enhanced capacitively coupled plasma （CCP）- is successfully developed. The plasma can be generated using different frequency configurations, such as ICP-enhanced single-frequency ca- pacitively coupled plasma （SFCCP） and dual-frequency capacitively coupled plasma （DFCCP）. The characteristics of the plasma in the following frequency combinations are mainly investigated using a Langmuir probe, SFCCP （60 MHz）, DFCCP （60 MHz, 13.56 MHz）, SFCCP （60 MHz） and inductively coupled plasma （13.56 MHz）, DFCCP （60 MHz, 13.56 MHz） and inductively coupled plasma （13.56 MHz）. In this letter, the nitrogen and hydrogen mixture gas discharge charac- teristics of different configurations are studied. After the analysis, we can acquire the electron temperature and ion density. Then, the effect of inductively coupled discharge on SFCCP and DFCCP can be summarized. In our preliminary investigations, the main results can be given as follows. ICP can make the density of SFCCP increase and the distribution of the electron temper- ature in a radial direction more uniform. In addition, ICP not only can make the ion density of DFCCP increase, but also can improve the radial uniformity. F^rther experiments may be needed to clarify the mechanism.展开更多
Layered Li-rich oxides have attracted much attention because of higher capacity than that of traditional layered oxides(more than 250 mAh g^(−1)).However,the intrinsic issues of Li-rich cathode materials suffer from l...Layered Li-rich oxides have attracted much attention because of higher capacity than that of traditional layered oxides(more than 250 mAh g^(−1)).However,the intrinsic issues of Li-rich cathode materials suffer from lattice oxygen loss,poor rate capability,voltage fade,and limited cycle life.To tackle these problems,the Li-rich cathode containing intergrown layer and spinel phases was proposed,and this heterostructure material meets the requirements of high energy and stable surface with a fast Li^(+)diffusion channel.Herein,we review the recent progress and in-depth understanding about heterostructure including microstructure and morphology,performance of advancement and degradation mechanisms,and modification strategies.Special attention is given to the high-performance energy mechanism as follows:(a)spinel phase and oxygen vacancy jointly enhance the lattice structure and prevent the irreversible oxygen release,(b)higher capacity is achieved by promotion of activation of Li_(2)MnO_(3) phase and control of the activation rate to realize stable long-term cyclability,and(c)spinel phase provides the 3D interconnected Li^(+)diffusion channels and protects the surface region from side reactions.The other issue that aroused interest is the undesirable changes of phase transition and degradation mechanisms as follows:(a)the key reconstruction process is to produce a“good”spinel to maintain the surface and interior structure stability.(b)It is significant to figure out the structure degradation and phase transition mechanism in the cycled heterostructure.This review aims to provide inspiration and opportunities for the design of high-energy-density cathode materials,thereby bridging the gap between laboratory research and practical battery applications.展开更多
基金The project supported by the Natural Science Foundation of Guangdong province (No. 000675) the Key project tackled of Guangdong province (ZKM01401G)
文摘The ion density distribution in the reaction chamber was diagnosed by a Langmuir probe. The rules of the ion density distribution were obtained under the pressures of 9 Pa, 13 Pa, 27 Pa and 53 Pa in the reaction chamber, different radio-frequency powers and different positions. The result indicates that the ion density decreases as the pressure increases, and increases as the power decreases. The ion density of axial position z =0 achieves 5.8×1010 on the center of coil under the power of 200 w and pressure of 9 Pa in the reaction chamber.
基金supported by the Technological Project of Shenzhen,China(No.JC201005280485A)the Planned S&T Program of Shenzhen,China(No.JC201105170703A)the Foundation of Guangdong Province,China(No.2012LYM0115)
文摘Diagnosis of the particle number density of plasma plays an important role in the understanding of plasma sources and processing.Regular radiation signals from plasma oscillation in filaments of atmospheric nitrogen discharge,which were excited by the injection of secondary electron beams during the propagation of the streamer,are employed to determine the ion density of plasma and its evolution in the filaments.Results show that the density of N4＋ in a filament of atmospheric nitrogen discharge is of the order of 1013 cm-3.It is also found that the recombination processes play a dominant role in plasma decay,and that the ion density decreases non-monotonically with time during streamer propagation.
文摘Neon glow discharge cleaning was firstly attempted in Large Helical Device(LHD) instead of He glow discharge to remove hydrogen neutrals and to control the ion density, n_i.The Ne glow discharge continued for 8 hours overnight after a three-day experiment. At the secondnight H_α emission became weaker than the emission usually observed in the He glow discharge. Aclear reduction of the hydrogen influx was also observed in neutral beam injection (NBI) dischargeswith Ne puff, whereas the neon recycling was strongly enhanced with appearance of a flat densityprofile. As a result, the lowest density limit was further reduced down to 0.2 X 10^(13)cm^(-3). Theuse of Ar puff formed a peaked density profile with a high T_i of 7 keV.
文摘Aim To investigate the influence of ion density( n i) on the deposition of wurtzite GaN films on the substrate of α Al 2O 3(0001) by electron cyclotron resonance plasma. Methods Langmuir probe measurement, Double crystal X ray diffraction and Hall measurement were used. Results The quality of GaN film strongly depended on its growth condition. The higher ion density resulted in a higher amount ratio of N/Ga and a lower background electron concentration of GaN film. When the GaN was prepared in the ion density of 2 0×10 11 cm -3 , the amount ratio of N/Ga was close to 1, the electron background density was 3 7×10 18 cm -3 and its full width at half magnitude(FWHM) was 16?arcmin. Conclusion The quality of GaN film can be improved by raising the plasma density.
文摘The effect of ion current density of argon plasma on target sputtering in magnetron sputtering process was investigated. Using home-made ion probe with computer-based data acquisition system, the ion current density as functions of discharge power, gas pressure and positions was measured. A double-hump shape was found in ion current density curve after the analysis of the effects of power and pressure. The data demonstrate that ion current density increases with the increase in gas pressure in spite of slightly at the double-hump site, sharply at wave-trough and side positions. Simultaneously, the ion current density increases upon increase in power. Es- pecially, the ion current density steeply increases at the double-hump site. The highest energy of the secondary electrons arising from Larmor precession was found at the double-hump position, which results in high ion density. The target was etched seriously at the double-hump position due to the high ion density there. The data indicates that the increase in power can lead to a high sputtering speed rate.
基金Supported by the National Natural Science Foundation of China under Grant No 21363016the Natural Science Foundation of Jiangxi Province under Grant No 20142BAB216030the PhD Early Development Program of Nanchang Hangkong University under Grant No EA201502007
文摘The layered Li2MnO3 is investigated by using the first-principles calculations within the GGA and GGA-t-U scheme, respectively. Within the GGA4-U approach, the calculated intercalation voltage （ranges from 4,5 V to 4.9 V） is found to be in good agreement with experiments. From the analysis of electronic structure, the pure phase Li2MnO3 is insulating, which is indicative of poor electronic-conduction properties. However, further studies of lithium ion diffusion in bulk Li2MnO3 show that unlike the two-dimensional diffusion pathways in rock salt structure layered cathode materials, lithium can diffuse in a three-dimensional pathway in Li2MnO3, with moderate lithium migration energy barrier ranges from 0.57 to 0.63 e V.
基金This work is undertaken in CETP, Paris and supported in part by CNR.S-France
文摘The in-situ measurements of the ionospheric plasma that we use come from two instruments of the scientific payload of the satellite DEMETER; the plasma analyser IAP （Instrument d＇analyse du plasma） and the Langmuir probe ISL （Instrument Sonde de Langmuir）. DEMETER is a micro-satellite realized by the CNES（Centre National d＇Etudes Spatiales, France） with a principal objective to seek a possible influence of the seismic activity on the electromagnetic waves in the ionosphere and on the ionospheric plasma. The satellite was placed on June 29, 2004, in a circular and quasi helio-synchronous orbit at -710 km altitude. The experiments function primarily at mid-latitudes （from ＋60° to -60°）. The IAP data were analysed to deduce the ion population （densities of the dominant ions, i.e. generally O^＋, H^＋ and He^＋） therefore the total ion density. The use of data IAP thus requires some precaution to make sure that the electric equilibrium conditions of the satellite, such as the satellite potential （Фsat）, are obtained during the treatment of routine, does not induce an error of measurement. When this potential is negative, the minority light ions H^＋ and He^＋ can be measured in a reliable way when their proportion is above 3% to 5% of that of O^＋. The critical limitation is： under certain conditions, the satellite potential becomes positive and reach a value about -0.5 V so that it becomes impossible to measure H^＋ ions. This is likely to involve a significant error on the composition and the density of the plasma. Therefore we carried out a calibration to estimate the missing density. The ISL experiment （Langmuir probe） provided the collected current/polarized tension characteristics of a cylindrical probe from which both electron density Ne and temperature Te were obtained. In some situations it is necessary to examine the accuracy of the electron density using another technique, for instance the high frequency （HF） spectrogram, provided by ICE （instrument champ electrique） instrument. This technique could give precise information about the accuracy of the data provided by the plasma analyser and the Langmuir probes. The observed satellite surface potential was found to be remarkable and subject of question. It displayed negative values at daytime and positive at night.
基金Project supported by the National Natural Science Foundation of China （Grant Nos 10247005 and 70071047） and the Scientific Research Foundation of China University of Mining and Technology for the Young （Grant No 2005A037）.
文摘The K-V beam through an axisymmetric uniform-focusing channel is studied using the particle-core model. The beam halo-chaos is found, and a sample function controller is proposed based on mechanism of halo formation and strategy of controlling halo-chaos. We perform multiparticle simulation to control the halo by using the sample function controller. The numerical results show that our control method is effective. We also find that the radial ion density changes when the ion beam is in the channel： not only can the halo-chaos and its regeneration be eliminated by using the sample function control method, but also the density uniformity can be found at the beam＇s centre as long as an appropriate control method is chosen.
基金supported by International Thermonuclear Experimental Reactor(ITER) program special(Grant No.2013GB114003)National Natural Science Foundation of China(project approval Nos.11275135,11475122)
文摘A high-flux linear plasma device in Sichuan University plasma-surface interaction（SCU-PSI）based on a cascaded arc source has been established to simulate the interactions between helium and hydrogen plasma with the plasma-facing components in fusion reactors.In this paper,the helium plasma has been characterized by a double-pin Langmuir probe.The results show that the stable helium plasma beam with a diameter of 26 mm was constrained very well at a magnetic field strength of 0.3 T.The core density and ion flux of helium plasma have a strong dependence on the applied current,magnetic field strength and gas flow rate.It could reach an electron density of1.2×10^19m^-3and helium ion flux of 3.2×10^22m^-2s^-1,with a gas flow rate of 4 standard liter per minute,magnetic field strength of 0.2 T and input power of 11 k W.With the addition of-80 Vapplied to the target to increase the helium ion energy and the exposure time of 2 h,the flat top temperature reached about 530°C.The different sizes of nanostructured fuzz on irradiated tungsten and molybdenum samples surfaces under the bombardment of helium ions were observed by scanning electron microscopy.These results measured in the SCU-PSI linear device provide a reference for International Thermonuclear Experimental Reactor related PSI research.
基金the financial support of the National Natural Science Foundation of China under contract No. 50172051
文摘Aluminum doped zinc oxide （AZO） thin films were prepared by DC magnetron sputtering at low substrate temperature. A coaxial solenoid coil was placed near the magnetron target to enhance the plasma density （Ji）. The enhanced plasma density improved significantly the bulk resistivity （p） and its homogeneity in spatial distribution of AZO films. X-ray diffraction （XRD） analysis revealed that the increased Ji had influenced the crystallinity, stress relaxation and other material properties. The AZO films deposited in low plasma density （LPD） mode showed marked variation in p （ranging from -6.5x10-2 to 1.9x10-3 Ω.cm）, whereas those deposited in high plasma density （HPD） mode showed a better homogeneity of films resistivity （ranging from ~1.3x10-3 to 3.3x10-3 ~.cm） at different substrate positions. The average visible transmittance in the wavelength range of 500-800 nm was over 80%, irrespective of the deposition conditions. The atomic force microscopy （AFM） surface morphology showed that AZO films deposited in HPD mode were smoother than that in LPD mode. The high plasma density produced by the coaxial solenoid coil improved the electrical property, surface morphology and the homogeneity in spatial distribution of AZO films deposited at low substrate temperature.
基金supported by the National Magnetic Confinement Fusion Science Program of China(Nos.2011GB108011 and 2010GB103001)the Major International(Regional)Project Cooperation and Exchanges of China(No.11320101005)the Startup Fund from Fuzhou University(No.510071)
文摘An experimental investigation of the saturation ion current densities （Jions） in hydrogen inductively coupled plasma （ICP） produced by a large-power （2-32 kW） radio frequency （RF） generator is reported, then some reasonable explanations are given out. With the increase of RF power, the experimental results show three stages： in the first stage （2-14 kW）, the electron temperature will rise with the increase of RF power in the ICP, thus, the Jions increases continually as the electron temperature rises in the ICP. In the second stage （14 20 kW）, as some H- ions lead to the mutual neutralization （MN）, the slope of Jio^s variation firstly decreases then increases. In the third stage （20-32 kW）, both the electronic detachment （ED） and the associative detachment （AD） in the ICP result in the destruction of H- ions, therefore, the increased amplitude of the Jions in the third stage is weaker than the one in the first stage. In addition, with the equivalent transformer model, we successfully Explain that the Jions at different radial locations in ICP has the same rule. Finally, it is found that the Jions has nothing to do with the outer/inner puffing gas pressure ratio, which is attributed to the high-speed movement of hydrogen molecules.
基金by State Grid Shandong Electric Power Company(52062618001M)。
文摘Corona discharge suppression for high-voltage direct-current(HVDC)transmission lines at line terminals such as converter stations is a subject that requires attention.In this paper,a method based on a conductor covered with dielectric film is proposed and implemented through a bench-scale setup.Compared with the bare conductor,the corona discharge suppression effect of the dielectric-film-covered conductor under positive polarity is studied from the composite field strength and ion current density using a line-plate experimental device.The influences of film thickness and film material on the corona discharge suppression effect are investigated.The charge accumulation and dissipation characteristics of different film materials are also studied.The results show that the conductor covered with dielectric film has excellent ability to inhibit corona discharge.The ground-level composite field strength of the conductor covered with dielectric film is lower than its nominal field strength,and its ion current density is at the nA m^(−2) level.The corona threshold voltage can be promoted by increasing the film thickness,but the ability to inhibit corona discharge becomes weak.The larger the surface electric field strength,the more charge accumulated,but the faster the charge dissipation rate.Compared with polyvinyl chloride film,cross-linked polyethylene film has stronger charge accumulation ability and slower charge dissipation rate,which can better restrain the corona discharge of HVDC transmission lines.
基金financial support from the National Program on Key Basic Research Project of China (No. 2014CB239701)the National Natural Science Foundation of China (Nos. 51372116, 51672128, 21773118)+1 种基金Prospective Joint Research Project of Cooperative Innovation Fund of Jiangsu Province (No. BY2015003-7)Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)
文摘Hybrid ion capacitors have been considered as a very attractive energy source with high energy density and power density since it combines both merits of lithium ion batteries and supercapacitors. However,their commercial application has been limited by the mismatch of charge-storage capacity and electrode kinetics between the capacitor-type cathode and battery-type anode. Herein, B and N dual-doped 3D superstructure carbon cathode is prepared through a facile template method. It delivers a high specific capacity, excellent rate capability and good cycling stability due to the B, N dual-doping, which has a profound effect in control the porosity, functional groups, and electronic conductivity for the carbon cathode. The hybrid ion capacitors using B, N dual-doping carbon cathode and prelithiated graphite anode show a high energy density of 115.5 Wh/kg at 250 W/kg and remain about 53.6 Wh/kg even at a high power density of 10 kW/kg. Additionally, the novel hybrid device achieves 76.3% capacity retention after 2000 cycles tested at 1250 W/kg power density. Significantly, the simultaneous manipulation of heteroatoms in carbon materials provides new opportunities to boost the energy and power density for hybrid ion capacitors.
文摘Ischemic postconditioning renders brain tissue tolerant to brain ischemia,thereby alleviating ischemic brain injury.However,the exact mechanism of action is still unclear.In this study,a rat model of global brain ischemia was subjected to ischemic postconditioning treatment using the vessel occlusion method.After 2 hours of ischemia,the bilateral common carotid arteries were blocked immediately for 10 seconds and then perfused for 10 seconds.This procedure was repeated six times.Ischemic postconditioning was found to mitigate hippocampal CA1 neuronal damage in rats with brain ischemia,and up-regulate acid-sensing ion channel 2a expression at the m RNA and protein level.These findings suggest that ischemic postconditioning up-regulates acid-sensing ion channel 2a expression in the rat hippocampus after global brain ischemia,which promotes neuronal tolerance to ischemic brain injury.
文摘The article theoretically studied the charge-exchange effects on space charge limitedelectron and ion current densities of non-relativistic one-dimensional slab ion diode, and comparedwith those of without charge exchange.
基金National High-tech Research & Development Plan(863 Projeet)(No.2008AA062317)National Natural Science Foundation of China(No.50578020)
文摘A mini-type of plasma source was studied experimentally. The results showed that the plasma density, which was generated by an atmospheric non-equilibrium plasma source, rises with the increase in driving electric-field and the momentum of gas particles. For a driving electricfield of 56 kV/cm and a gas particles＇ momentum of 10^9 × 10^-22 g·m/s, the ion density can exceed 10^10/cm^3 while the effective volume of the plasma source is only 2.5 cm^2. This study may help develop a method to generate a minitype plasma source with low energy consumption but high ion concentration. This source can be used in chemical industry, environmental engineering and military applications.
基金supported by the technological project of Shenzhen, China (No.200620)Shenzhen Key Laboratory of Sensors Technology Open Fund of China (Nos.SST200908, SST200911)
文摘A spark generator was employed to assist surface barrier discharge （SBD） in nitrogen at atmospheric pressure. The influence of spark discharge on the SBD electrical behavior is investigated by means of volt-ampere characteristics. Also, the electron density of plasma in the filament of each SBD arrangement is determined by plasma radiation method. It is found that the filaments in spark-assistant SBD are much stronger, while the corresponding mean electron density is much lower. Results show that the spark generator can improve the uniformity of SBD in atmospheric nitrogen in a particular range of applied frequency.
基金National Natural Science Foundation of China under Grant Nos.10247005 and 70071047the Scientific Research Foundation of China University of Mining and Technology for the Young Teachers under Grant No.OK060119
文摘We study an intense beam propagating through the double periodic focusing channel by the particle-coremodel,and obtain the beam envelope equation.According to the Poincare-Lyapunov theorem,we analyze the stabilityof beam envelope equation and find the beam halo.The soliton control method for controlling the beam halo-chaos isput forward based on mechanism of halo formation and strategy of controlling beam halo-chaos,and we also prove thevalidity of the control method,and furthermore,the feasible experimental project is given.We perform multiparticlesimulation to control the halo by using the soliton controller.It is shown that our control method is effective.We alsofind the radial ion density changes when the ion beam is in the channel,not only the halo-chaos and its regeneration canbe eliminated by using the nonlinear control method,but also the density uniformity can be found at beam's centre aslong as an appropriate control method is chosen.
基金supported by National Natural Science Foundation of China(Nos.11075114,10975106)the Priority Academic Program Development of Jiangsu Higher Education Institutions of China
文摘A novel technique to generate high-density plasma-called inductively coupled plasma （ICP）, enhanced capacitively coupled plasma （CCP）- is successfully developed. The plasma can be generated using different frequency configurations, such as ICP-enhanced single-frequency ca- pacitively coupled plasma （SFCCP） and dual-frequency capacitively coupled plasma （DFCCP）. The characteristics of the plasma in the following frequency combinations are mainly investigated using a Langmuir probe, SFCCP （60 MHz）, DFCCP （60 MHz, 13.56 MHz）, SFCCP （60 MHz） and inductively coupled plasma （13.56 MHz）, DFCCP （60 MHz, 13.56 MHz） and inductively coupled plasma （13.56 MHz）. In this letter, the nitrogen and hydrogen mixture gas discharge charac- teristics of different configurations are studied. After the analysis, we can acquire the electron temperature and ion density. Then, the effect of inductively coupled discharge on SFCCP and DFCCP can be summarized. In our preliminary investigations, the main results can be given as follows. ICP can make the density of SFCCP increase and the distribution of the electron temper- ature in a radial direction more uniform. In addition, ICP not only can make the ion density of DFCCP increase, but also can improve the radial uniformity. F^rther experiments may be needed to clarify the mechanism.
基金supported by the National Natural Science Foundation of China(22179008 and 21875022)the Yibin“Jie Bang Gua Shuai”(2022JB004)+1 种基金support from the Postdoctoral Fellowship Program of CPSF(GZB20230931)the Special Support of Chongqing Postdoctoral Research Project(2023CQBSHTB2041).
文摘Layered Li-rich oxides have attracted much attention because of higher capacity than that of traditional layered oxides(more than 250 mAh g^(−1)).However,the intrinsic issues of Li-rich cathode materials suffer from lattice oxygen loss,poor rate capability,voltage fade,and limited cycle life.To tackle these problems,the Li-rich cathode containing intergrown layer and spinel phases was proposed,and this heterostructure material meets the requirements of high energy and stable surface with a fast Li^(+)diffusion channel.Herein,we review the recent progress and in-depth understanding about heterostructure including microstructure and morphology,performance of advancement and degradation mechanisms,and modification strategies.Special attention is given to the high-performance energy mechanism as follows:(a)spinel phase and oxygen vacancy jointly enhance the lattice structure and prevent the irreversible oxygen release,(b)higher capacity is achieved by promotion of activation of Li_(2)MnO_(3) phase and control of the activation rate to realize stable long-term cyclability,and(c)spinel phase provides the 3D interconnected Li^(+)diffusion channels and protects the surface region from side reactions.The other issue that aroused interest is the undesirable changes of phase transition and degradation mechanisms as follows:(a)the key reconstruction process is to produce a“good”spinel to maintain the surface and interior structure stability.(b)It is significant to figure out the structure degradation and phase transition mechanism in the cycled heterostructure.This review aims to provide inspiration and opportunities for the design of high-energy-density cathode materials,thereby bridging the gap between laboratory research and practical battery applications.
