This article describes the equilibrium structure of the solar interior plasma (SIP) and solar wind plasma (SWP) in detail under the framework of the gravito-electrostatic sheath (GES) model. This model gives a precise...This article describes the equilibrium structure of the solar interior plasma (SIP) and solar wind plasma (SWP) in detail under the framework of the gravito-electrostatic sheath (GES) model. This model gives a precise definition of the solar surface boundary (SSB), surface origin mechanism of the subsonic SWP, and its supersonic acceleration. Equilibrium parameters like plasma potential, self-gravity, population density, flow, their gradients, and all the relevant inhomogeneity scale lengths are numerically calculated and analyzed as an initial value problem. Physical significance of the structure condition for the SSB is discussed. The plasma oscillation and Jeans time scales are also plotted and compared. In addition, different coupling parameters, and electric current profiles are also numerically studied. The current profiles exhibit an important behavior of directional reversibility, i.e., an electrodynamical transition from negative to positive value. It occurs beyond a few Jeans lengths away from the SSB. The virtual spherical surface lying at the current reversal point, where the net current becomes zero, has the property of a floating surface behavior of the real physical wall. Our investigation indicates that the SWP behaves as an ion current-carrying plasma system. The basic mechanism behind the GES formation and its distinctions from conventional plasma sheath are discussed. The electromagnetic properties of the Sun derived from our model with the most accurate available inputs are compared with those of others. These results are useful as an input element to study the properties of the linear and nonlinear dynamics of various solar plasma waves, oscillations and instabilities.展开更多
Readout electronics is developed for a prototype spectrometer for in situ measurement of low-energy ions of30 e V/e–20 ke V/e in the solar wind plasma.A low-noise preamplifier/discriminator(A111F) is employed for eac...Readout electronics is developed for a prototype spectrometer for in situ measurement of low-energy ions of30 e V/e–20 ke V/e in the solar wind plasma.A low-noise preamplifier/discriminator(A111F) is employed for each channel to process the signal from micro-channel plate(MCP) detectors.A high-voltage(HV) supply solution based on a HV module and a HV optocoupler is adopted to generate a fast sweeping HV and a fixed HV.Due to limitation of telemetry bandwidth in space communication,an algorithm is implemented in an FPGA(field programmable gate array) to compress the raw data.Test results show that the electronics achieves a 1 MHz event rate and a large input dynamic range of 95 p C.A slew rate of 0.8 V/ls and an integral nonlinearity of 0.7-LSB for the sweeping HV,and a precision of less than 0.8 % for the fixed HV are obtained.A vacuum beam test shows an energy resolution of 12 ± 0.7 % full width at half maximum(FWHM) is achieved,and noise counts are less than10/sec,indicating that the performance meets the physical requirement.展开更多
Emitted multi-crystalline silicon and black silicon solar cells are conformal doped by ion implantation using the plasma immersion ion implantation (PⅢ) technique. The non-uniformity of emitter doping is lower than...Emitted multi-crystalline silicon and black silicon solar cells are conformal doped by ion implantation using the plasma immersion ion implantation (PⅢ) technique. The non-uniformity of emitter doping is lower than 5 %. The secondary ion mass spectrometer profile indicates that the PⅢ technique obtained 100-rim shallow emitter and the emitter depth could be impelled by furnace annealing to 220 nm and 330 nm at 850 ℃ with one and two hours, respectively. Furnace annealing at 850 ℃ could effectively electrically activate the dopants in the silicon. The efficiency of the black silicon solar cell is 14.84% higher than that of the mc-silicon solar cell due to more incident light being absorbed.展开更多
This paper reports that the intrinsic microcrystalline silicon (μc-Si:H) films are prepared with plasma enhanced chemical vapour deposition from silane/hydrogen mixtures at 200℃ with the aim to increase the depos...This paper reports that the intrinsic microcrystalline silicon (μc-Si:H) films are prepared with plasma enhanced chemical vapour deposition from silane/hydrogen mixtures at 200℃ with the aim to increase the deposition rate. An increase of the deposition rate to 0.88 nm/s is obtained by using a plasma excitation frequency of 75 MHz. This increase is obtained by the combination of a higher deposition pressure, an increased silane concentration, and higher discharge powers. In addition, the transient behaviour, which can decrease the film crystallinity, could be prevented by filling the background gas with H2 prior to plasma ignition, and selecting proper discharging time after silane flow injection. Material prepared under these conditions at a deposition rate of 0.78nm/s maintains higher crystallinity and fine electronic properties. By H-plasma treatment before i-layer deposition, single junction μc-Si:H solar cells with 5.5% efficiency are fabricated.展开更多
The thermal pyrolysis of natural gas as a clean hydrogen production route is examined. The concept of a double-walled reactor tube is proposed and implemented. Preliminary experiments using an external plasma heating ...The thermal pyrolysis of natural gas as a clean hydrogen production route is examined. The concept of a double-walled reactor tube is proposed and implemented. Preliminary experiments using an external plasma heating source are carried out to validate this concept. The results point out the efficient CH4 dissociation above 1850 K (CH4 conversion over 90%) and the key influence of the gas residence time. Simulations are performed to predict the conversion rate of CH4 at the reactor outlet, and are consistent with experimental tendencies. A solar reactor prototype featuring four independent double-walled tubes is then developed. The heat in high temperature process required for the endothermic reaction of natural gas pyrolysis is supplied by concentrated solar energy. The tubes are heated uniformly by radiation using the blackbody effect of a cavity-receiver absorbing the concentrated solar irradiation through a quartz window. The gas composition at the reactor outlet, the chemical conversion of CH4, and the yield to H2 are determined with respect to reaction temperature, inlet gas flow-rates, and feed gas composition. The longer the gas residence time, the higher the CH4 conversion and H2 yield, whereas the lower the amount of acetylene. A CH4 conversion of 99% and H2 yield of about 85% are measured at 1880 K with 30% CH4 in the feed gas (6 L/min injected and residence time of 18 ms), A temperature increase from 1870 K to 1970 K does not improve the H2 yield.展开更多
The mask-free SF6/O2 plasma etching technique is used to produce surface texturization of mc-silicon solar cells for efficient light trapping in this work. The SEM images and mc-silicon etching rate show the influence...The mask-free SF6/O2 plasma etching technique is used to produce surface texturization of mc-silicon solar cells for efficient light trapping in this work. The SEM images and mc-silicon etching rate show the influence of plasma power, SF6/O2 flow ratios and etching time on textured surface. With the acidic-texturing samples as a reference, the reflection and IQE spectra are obtained under different experimental conditions. The IQE spectrum measurement shows an evident increase in the visible and infrared responses. By using the optimized plasma power, SF6/O2 flow ratios and etching time, the optimal etticiency of 15.7% on 50 × 50mm2 reactive ion etching textured mc-silicon silicon solar ceils is achieved, mostly due to the improvement in the short-circuit current density. The corresponding open-circuit voltage, short-circuit current density and fill factor are 611 m V, 33.6 mA/cm2, 76.5%, respectively. It is believed that such a low-cost and high-performance texturization process is promising for large-scale industrial silicon solar cell manufacturing.展开更多
Photothermal membrane distillation(MD)is a promising technology for desalination and water purification.However,solar-thermal conversion suffers from low energy efficiency(a typical solar-water efficiency of ~50%),whi...Photothermal membrane distillation(MD)is a promising technology for desalination and water purification.However,solar-thermal conversion suffers from low energy efficiency(a typical solar-water efficiency of ~50%),while complex modifications are needed to reduce membrane fouling.Here,we demonstrate a new concept of solar vapour gap membrane distillation(SVGMD)synergistically combining self-guided water transport,localized heating,and separation of membrane from feed solution.A free-standing,multifunctional light absorber based on graphene array is custom-designed to locally heat the thin water layer transporting through graphene nanochannels.The as-generated vapour passes through a gap and condenses,while salt/contaminants are rejected before reaching the membrane.The high solar-water efficiency(73.4% at 1 sun),clean water collection ratio(82.3%),excellent anti-fouling performance,and stable permeate flux in continuous operation over 72 h are simultaneously achieved.Meanwhile,SVGMD inherits the advantage of MD in microorganism removal and water collection,enabling the solar-water efficiency 3.5 times higher compared to state-of-the-art solar vapour systems.A scaled system to treat oil/seawater mixtures under natural sunlight is developed with a purified water yield of 92.8 kg m-2 day-1.Our results can be applied for diverse mixed-phase feeds,leading to the next-generation solar-driven MD technology.展开更多
We carried out one-dimensional hybrid simulations of resonant scattering of protons and He2+ ions by ion cyclotron waves in an initially homogeneous, collisionless and magnetized plasma. The initial ion cyclotron wave...We carried out one-dimensional hybrid simulations of resonant scattering of protons and He2+ ions by ion cyclotron waves in an initially homogeneous, collisionless and magnetized plasma. The initial ion cyclotron waves have a power spectrum and propagate both outward and inward. Due to the resonant interaction with the protons and He2+ ions, the wave power will be depleted in the resonance region. Both the protons and He2+ ions can be resonantly heated in the direction perpendicular to the ambient magnetic field and leading to anisotropic velocity distributions, with the anisotropy higher for the He2+ ions than for the protons. At the same time, the anisotropies of the protons and He2+ ions are inversely correlated with the plasma β||p= 8πnpkBT||p/b02, consistent with the prediction of the quasilinear theory (QLT).展开更多
A highly charged manned spacecraft threatens the life of an astronaut and extravehicular activity, which can be effectively reduced by controlling the spacecraft surface charging. In this article, the controlling of s...A highly charged manned spacecraft threatens the life of an astronaut and extravehicular activity, which can be effectively reduced by controlling the spacecraft surface charging. In this article, the controlling of surface charging on Chinese Space Station (CSS) is investigated, and a method to reduce the negative potential to the CSS is the emission electron with a hollow cathode plasma eontactor. The analysis is obtained that the high voltage (HV) solar array of the CSS collecting electron current can reach 4.5 A, which can be eliminated by emitting an adequate electron current on the CSS. The theoretical analysis and experimental results are addressed, when the minimum xenon flow rate of the hollow cathode is 4.0 sccm, the emission electron current can neutralize the collected electron current, which ensures that the potential of the CSS can be controlled in a range of less than 21 V, satisfied with safety voltage. The results can provide a significant reference value to define a flow rate to the potential controlling programme for CSS.展开更多
This paper presents the generation of kinetic Alfv én wave(KAW) coherent structures of magnetic filaments applicable to solar wind at 1 AU,when the background plasma density is modified by parallel ponderomotive ...This paper presents the generation of kinetic Alfv én wave(KAW) coherent structures of magnetic filaments applicable to solar wind at 1 AU,when the background plasma density is modified by parallel ponderomotive force and Joule heating.The inhomogeneity in the magnetic field,which was included as a perturbation in the transverse direction of the magnetic field,takes energy from the main pump KAWs and generates the filamentary structures.When the intensity is high enough,the filaments are broken down and the energy initially confined to low wavenumbers is redistributed to higher wavenumbers,leading to cascades of energy at small scales less than the ion acoustic gyroradius or comparable to electron gyroradius.The magnetic field spectral profile is generated from the numerical simulation results,and its dependence on different directions of the wavevector and initial conditions of the simulation representing the transverse magnetic field inhomogeneity is studied.The relevance of these results with other spacecraft observations and measurements is also pointed out.展开更多
Resonant heating of H, O+5, and Mg+9 by parallel propagating ion cyclotron Alfven waves in solar coronal holes at a heliocentric distance is studied using the heating rate derived from the quasilinear theory. It is sh...Resonant heating of H, O+5, and Mg+9 by parallel propagating ion cyclotron Alfven waves in solar coronal holes at a heliocentric distance is studied using the heating rate derived from the quasilinear theory. It is shown that the particle-AlfVen-wave interaction is a significant microscopic process. The temperatures of the ions are rapidly increased up to the observed order in only microseconds, which implies that simply inserting the quasilinear heating rate into the fluid/MHD energy equation to calculate the radial dependence of ion temperatures may cause errors as the time scales do not match. Different species ions are heated by Alfven waves with a power law spectrum in approximately a mass order. To heat O+5 over Mg+9 as measured by the Ultraviolet Coronagraph Spectrometer (UVCS) in the solar coronal hole at a region ≥ 1.9.R, the energy density of Alfven waves with a frequency close to the O+5-cyclotron frequency must be at least double of that at the Mg+9-cyclotron frequency. With an appropriate wave-energy spectrum, the heating of H, O+5 and Mg+9 can be consistent with the UVCS measurements in solar coronal holes at a heliocentric distance.展开更多
A certain number of charges are deposited on the surface of high-voltage solar array because of effects of space plasma,high-energy charged particles,and solar illumination,hence the surface is charged.Phenomena of el...A certain number of charges are deposited on the surface of high-voltage solar array because of effects of space plasma,high-energy charged particles,and solar illumination,hence the surface is charged.Phenomena of electrostatic discharge(ESD) occur on the surface when the deposited charges exceed a threshold amount.In this paper,the mechanism of this ESD is discussed.The ground simulation experiment of the ESD using spacecraft material under surface charging is described,and a novel ESD protecting method for high-voltage solar array,i.e.an active protecting method based on the local strong electric field array is proposed.The results show that the reversal potential gradient field between the cover surface and the substrate materials of high-voltage solar array is a triggering factor for the ESD on the array.The threshold voltage for the ESD occurring on the surface is about 500 V.The charged particles could be deflected using the electric field active protecting method,and hence the ESD on the surface is avoided even when the voltage on the conductor array increases to a certain value.These results pave the way for further developing the protecting measures for high-voltage solar arrays.展开更多
A brief review of our courrent understanding of the interaction between the innermost Galilean satellite,Io,and Jupiter’s magnetosphere is presented.Particular consideration is given to the neutral clouds and lo plas...A brief review of our courrent understanding of the interaction between the innermost Galilean satellite,Io,and Jupiter’s magnetosphere is presented.Particular consideration is given to the neutral clouds and lo plasma torus which have been monitored by ground-based and Earth-orbiting observations for the past 25 years.Detailed investigation of observed phenomena in the neutral clouds has revealed several processes which have a direct bearing on the nature of the interaction and suggest that a revision of the existing concept is necessary.Similarly.observed variability in the torus indicates the presence of complex plasma processes which at present remain unexplained.Areas where further research is necessary are outlined.展开更多
A new theoretical prediction that a plasma can produce antineutrinos is used to solve the solar neutrino problem. The difference between electron-positron induced fusion, and inertial fusion experiments that have been...A new theoretical prediction that a plasma can produce antineutrinos is used to solve the solar neutrino problem. The difference between electron-positron induced fusion, and inertial fusion experiments that have been unsuccessful so far as commercial fusion reactors is also discussed.展开更多
Hetero-junction solar cells with an mc-Si:H window layer were achieved. The open voltage is increased while short current is decreased with increasing the mc-Si:H layer′s thickness of emitter layer. The highest of Vo...Hetero-junction solar cells with an mc-Si:H window layer were achieved. The open voltage is increased while short current is decreased with increasing the mc-Si:H layer′s thickness of emitter layer. The highest of Voc of 597 mV has obtained. When fixed the thickness of 30 nm, changing the N type from amorphous silicon layer to micro-crystalline layer, the efficiency of the hetero-junction solar cells is increased. Although the hydrogen etching before deposition enables the c-Si substrates to become rough by AFM images, it enhances the formation of epitaxial-like micro-crystalline silicon and better parameters of solar cell can be obtained by implying this process. The best result of efficiency is 13.86% with the Voc of 549.8 mV, Jsc of 32.19 mA·cm-2 and the cell′s area of 1 cm2.展开更多
This paper calculates the redshift of the 2292 MHz radio photon emitted by the Pioneer-6 space probe. The signal crossed the solar corona on the days close to the solar occultation between November and December 1968, ...This paper calculates the redshift of the 2292 MHz radio photon emitted by the Pioneer-6 space probe. The signal crossed the solar corona on the days close to the solar occultation between November and December 1968, the only ones for which scientific data are available, until it reached a terrestrial radio receiver. The specific study is based on a calculated orbital model of the Earth and Pioneer-6 system made on a scale of 1:100,000 by a CAD, on the New Tired Light theory adapted to the geometric and physical configuration of the topic and on a computational method. Removing the Doppler shift contributions of proper and rotational motions, due to the set-up of the receiver, and excluding the recombination factor of neutral hydrogen, which is irrelevant for distances within 1 AU, the calculation of the redshift can be traced back to the interactions between the radio signal and the electrons of the solar corona alone. The latter are contained in a Stroemgren sphere and photo-ionized by solar radiation in the UV and X-ray range. Furthermore, in order to have an interactional redshift contribution, the electrons have to satisfy the Wigner-Crystal Precondition for which their unitary potential energy is greater than their kinetic energy. Otherwise, a Thomson scattering process takes place in which the energy of the radio photon remains unchanged. The comparison between the gravitational redshift together with the interactional redshift detected from this study methodology and the total redshift obtained from other scientific studies shows a similarity between the curves, including the observational data, both in terms of values, trend of the graphs and single punctual variations.展开更多
A novel theory of acoustics in solar energy supporting the principle of source and sink of solar energy is presented. The significance of the theory is in ascertaining the aftermaths of turning off solar energy. An am...A novel theory of acoustics in solar energy supporting the principle of source and sink of solar energy is presented. The significance of the theory is in ascertaining the aftermaths of turning off solar energy. An amplifier constituting of a parallel plate photovoltaic device connected to a potentiometer is illustrated. It was constructed with a pair of glass coated photovoltaic modules and polystyrene filled plywood board as back panel with air ventilation through a parallel plate channel of amplifier. The sample results obtained from experiments and simulation model are presented to support hypothesis of acoustics for a parallel plate photovoltaic device connected to a potentiometer. A phenomenon of photovoltaic amplification is formulated.展开更多
文摘This article describes the equilibrium structure of the solar interior plasma (SIP) and solar wind plasma (SWP) in detail under the framework of the gravito-electrostatic sheath (GES) model. This model gives a precise definition of the solar surface boundary (SSB), surface origin mechanism of the subsonic SWP, and its supersonic acceleration. Equilibrium parameters like plasma potential, self-gravity, population density, flow, their gradients, and all the relevant inhomogeneity scale lengths are numerically calculated and analyzed as an initial value problem. Physical significance of the structure condition for the SSB is discussed. The plasma oscillation and Jeans time scales are also plotted and compared. In addition, different coupling parameters, and electric current profiles are also numerically studied. The current profiles exhibit an important behavior of directional reversibility, i.e., an electrodynamical transition from negative to positive value. It occurs beyond a few Jeans lengths away from the SSB. The virtual spherical surface lying at the current reversal point, where the net current becomes zero, has the property of a floating surface behavior of the real physical wall. Our investigation indicates that the SWP behaves as an ion current-carrying plasma system. The basic mechanism behind the GES formation and its distinctions from conventional plasma sheath are discussed. The electromagnetic properties of the Sun derived from our model with the most accurate available inputs are compared with those of others. These results are useful as an input element to study the properties of the linear and nonlinear dynamics of various solar plasma waves, oscillations and instabilities.
基金supported by the National Key Scientific Instrument and Equipment Development Projects of the National Natural Science Foundation of China(No.41327802)the Fundamental Research Funds for the Central Universities(WK2030040066)
文摘Readout electronics is developed for a prototype spectrometer for in situ measurement of low-energy ions of30 e V/e–20 ke V/e in the solar wind plasma.A low-noise preamplifier/discriminator(A111F) is employed for each channel to process the signal from micro-channel plate(MCP) detectors.A high-voltage(HV) supply solution based on a HV module and a HV optocoupler is adopted to generate a fast sweeping HV and a fixed HV.Due to limitation of telemetry bandwidth in space communication,an algorithm is implemented in an FPGA(field programmable gate array) to compress the raw data.Test results show that the electronics achieves a 1 MHz event rate and a large input dynamic range of 95 p C.A slew rate of 0.8 V/ls and an integral nonlinearity of 0.7-LSB for the sweeping HV,and a precision of less than 0.8 % for the fixed HV are obtained.A vacuum beam test shows an energy resolution of 12 ± 0.7 % full width at half maximum(FWHM) is achieved,and noise counts are less than10/sec,indicating that the performance meets the physical requirement.
基金supported by the National Natural Science Foundation of China(Grant Nos.61106060 and 61274059)the National High Technology Research and Development Program of China(Grant No.2012AA052401)
文摘Emitted multi-crystalline silicon and black silicon solar cells are conformal doped by ion implantation using the plasma immersion ion implantation (PⅢ) technique. The non-uniformity of emitter doping is lower than 5 %. The secondary ion mass spectrometer profile indicates that the PⅢ technique obtained 100-rim shallow emitter and the emitter depth could be impelled by furnace annealing to 220 nm and 330 nm at 850 ℃ with one and two hours, respectively. Furnace annealing at 850 ℃ could effectively electrically activate the dopants in the silicon. The efficiency of the black silicon solar cell is 14.84% higher than that of the mc-silicon solar cell due to more incident light being absorbed.
基金supported by the State Key Development Program for Basic Research of China (Grant No 2006CB202601)Basic Research Project of Henan Province in China (Grant No 072300410140)
文摘This paper reports that the intrinsic microcrystalline silicon (μc-Si:H) films are prepared with plasma enhanced chemical vapour deposition from silane/hydrogen mixtures at 200℃ with the aim to increase the deposition rate. An increase of the deposition rate to 0.88 nm/s is obtained by using a plasma excitation frequency of 75 MHz. This increase is obtained by the combination of a higher deposition pressure, an increased silane concentration, and higher discharge powers. In addition, the transient behaviour, which can decrease the film crystallinity, could be prevented by filling the background gas with H2 prior to plasma ignition, and selecting proper discharging time after silane flow injection. Material prepared under these conditions at a deposition rate of 0.78nm/s maintains higher crystallinity and fine electronic properties. By H-plasma treatment before i-layer deposition, single junction μc-Si:H solar cells with 5.5% efficiency are fabricated.
基金European FP6 research project SOLHYCARB (Contract SES-CT-2006-19770)
文摘The thermal pyrolysis of natural gas as a clean hydrogen production route is examined. The concept of a double-walled reactor tube is proposed and implemented. Preliminary experiments using an external plasma heating source are carried out to validate this concept. The results point out the efficient CH4 dissociation above 1850 K (CH4 conversion over 90%) and the key influence of the gas residence time. Simulations are performed to predict the conversion rate of CH4 at the reactor outlet, and are consistent with experimental tendencies. A solar reactor prototype featuring four independent double-walled tubes is then developed. The heat in high temperature process required for the endothermic reaction of natural gas pyrolysis is supplied by concentrated solar energy. The tubes are heated uniformly by radiation using the blackbody effect of a cavity-receiver absorbing the concentrated solar irradiation through a quartz window. The gas composition at the reactor outlet, the chemical conversion of CH4, and the yield to H2 are determined with respect to reaction temperature, inlet gas flow-rates, and feed gas composition. The longer the gas residence time, the higher the CH4 conversion and H2 yield, whereas the lower the amount of acetylene. A CH4 conversion of 99% and H2 yield of about 85% are measured at 1880 K with 30% CH4 in the feed gas (6 L/min injected and residence time of 18 ms), A temperature increase from 1870 K to 1970 K does not improve the H2 yield.
基金Supported by the National Natural Science Foundation of China under Grant No 61306076the Youth Innovation Promotion of Chinese Academy under Grant No Y510411C31
文摘The mask-free SF6/O2 plasma etching technique is used to produce surface texturization of mc-silicon solar cells for efficient light trapping in this work. The SEM images and mc-silicon etching rate show the influence of plasma power, SF6/O2 flow ratios and etching time on textured surface. With the acidic-texturing samples as a reference, the reflection and IQE spectra are obtained under different experimental conditions. The IQE spectrum measurement shows an evident increase in the visible and infrared responses. By using the optimized plasma power, SF6/O2 flow ratios and etching time, the optimal etticiency of 15.7% on 50 × 50mm2 reactive ion etching textured mc-silicon silicon solar ceils is achieved, mostly due to the improvement in the short-circuit current density. The corresponding open-circuit voltage, short-circuit current density and fill factor are 611 m V, 33.6 mA/cm2, 76.5%, respectively. It is believed that such a low-cost and high-performance texturization process is promising for large-scale industrial silicon solar cell manufacturing.
基金supported by the National Natural Science Foundation of China (No. 51722604)the National Program for Support of Top-notch Young Professionals+1 种基金the financial support by the startup funding from the University of Nevadathe Australian Research Council for partial support
文摘Photothermal membrane distillation(MD)is a promising technology for desalination and water purification.However,solar-thermal conversion suffers from low energy efficiency(a typical solar-water efficiency of ~50%),while complex modifications are needed to reduce membrane fouling.Here,we demonstrate a new concept of solar vapour gap membrane distillation(SVGMD)synergistically combining self-guided water transport,localized heating,and separation of membrane from feed solution.A free-standing,multifunctional light absorber based on graphene array is custom-designed to locally heat the thin water layer transporting through graphene nanochannels.The as-generated vapour passes through a gap and condenses,while salt/contaminants are rejected before reaching the membrane.The high solar-water efficiency(73.4% at 1 sun),clean water collection ratio(82.3%),excellent anti-fouling performance,and stable permeate flux in continuous operation over 72 h are simultaneously achieved.Meanwhile,SVGMD inherits the advantage of MD in microorganism removal and water collection,enabling the solar-water efficiency 3.5 times higher compared to state-of-the-art solar vapour systems.A scaled system to treat oil/seawater mixtures under natural sunlight is developed with a purified water yield of 92.8 kg m-2 day-1.Our results can be applied for diverse mixed-phase feeds,leading to the next-generation solar-driven MD technology.
基金the National Natural Science Foundation of China.
文摘We carried out one-dimensional hybrid simulations of resonant scattering of protons and He2+ ions by ion cyclotron waves in an initially homogeneous, collisionless and magnetized plasma. The initial ion cyclotron waves have a power spectrum and propagate both outward and inward. Due to the resonant interaction with the protons and He2+ ions, the wave power will be depleted in the resonance region. Both the protons and He2+ ions can be resonantly heated in the direction perpendicular to the ambient magnetic field and leading to anisotropic velocity distributions, with the anisotropy higher for the He2+ ions than for the protons. At the same time, the anisotropies of the protons and He2+ ions are inversely correlated with the plasma β||p= 8πnpkBT||p/b02, consistent with the prediction of the quasilinear theory (QLT).
文摘A highly charged manned spacecraft threatens the life of an astronaut and extravehicular activity, which can be effectively reduced by controlling the spacecraft surface charging. In this article, the controlling of surface charging on Chinese Space Station (CSS) is investigated, and a method to reduce the negative potential to the CSS is the emission electron with a hollow cathode plasma eontactor. The analysis is obtained that the high voltage (HV) solar array of the CSS collecting electron current can reach 4.5 A, which can be eliminated by emitting an adequate electron current on the CSS. The theoretical analysis and experimental results are addressed, when the minimum xenon flow rate of the hollow cathode is 4.0 sccm, the emission electron current can neutralize the collected electron current, which ensures that the potential of the CSS can be controlled in a range of less than 21 V, satisfied with safety voltage. The results can provide a significant reference value to define a flow rate to the potential controlling programme for CSS.
文摘This paper presents the generation of kinetic Alfv én wave(KAW) coherent structures of magnetic filaments applicable to solar wind at 1 AU,when the background plasma density is modified by parallel ponderomotive force and Joule heating.The inhomogeneity in the magnetic field,which was included as a perturbation in the transverse direction of the magnetic field,takes energy from the main pump KAWs and generates the filamentary structures.When the intensity is high enough,the filaments are broken down and the energy initially confined to low wavenumbers is redistributed to higher wavenumbers,leading to cascades of energy at small scales less than the ion acoustic gyroradius or comparable to electron gyroradius.The magnetic field spectral profile is generated from the numerical simulation results,and its dependence on different directions of the wavevector and initial conditions of the simulation representing the transverse magnetic field inhomogeneity is studied.The relevance of these results with other spacecraft observations and measurements is also pointed out.
基金Supported by the National Natural Science Foundation of China.
文摘Resonant heating of H, O+5, and Mg+9 by parallel propagating ion cyclotron Alfven waves in solar coronal holes at a heliocentric distance is studied using the heating rate derived from the quasilinear theory. It is shown that the particle-AlfVen-wave interaction is a significant microscopic process. The temperatures of the ions are rapidly increased up to the observed order in only microseconds, which implies that simply inserting the quasilinear heating rate into the fluid/MHD energy equation to calculate the radial dependence of ion temperatures may cause errors as the time scales do not match. Different species ions are heated by Alfven waves with a power law spectrum in approximately a mass order. To heat O+5 over Mg+9 as measured by the Ultraviolet Coronagraph Spectrometer (UVCS) in the solar coronal hole at a region ≥ 1.9.R, the energy density of Alfven waves with a frequency close to the O+5-cyclotron frequency must be at least double of that at the Mg+9-cyclotron frequency. With an appropriate wave-energy spectrum, the heating of H, O+5 and Mg+9 can be consistent with the UVCS measurements in solar coronal holes at a heliocentric distance.
基金Project supported by National Natural Science Foundation of China(51177173), Elec- tromagnetic Environment Effect Key Laboratory Foundation(9140C87010313 JB34004).
文摘A certain number of charges are deposited on the surface of high-voltage solar array because of effects of space plasma,high-energy charged particles,and solar illumination,hence the surface is charged.Phenomena of electrostatic discharge(ESD) occur on the surface when the deposited charges exceed a threshold amount.In this paper,the mechanism of this ESD is discussed.The ground simulation experiment of the ESD using spacecraft material under surface charging is described,and a novel ESD protecting method for high-voltage solar array,i.e.an active protecting method based on the local strong electric field array is proposed.The results show that the reversal potential gradient field between the cover surface and the substrate materials of high-voltage solar array is a triggering factor for the ESD on the array.The threshold voltage for the ESD occurring on the surface is about 500 V.The charged particles could be deflected using the electric field active protecting method,and hence the ESD on the surface is avoided even when the voltage on the conductor array increases to a certain value.These results pave the way for further developing the protecting measures for high-voltage solar arrays.
文摘A brief review of our courrent understanding of the interaction between the innermost Galilean satellite,Io,and Jupiter’s magnetosphere is presented.Particular consideration is given to the neutral clouds and lo plasma torus which have been monitored by ground-based and Earth-orbiting observations for the past 25 years.Detailed investigation of observed phenomena in the neutral clouds has revealed several processes which have a direct bearing on the nature of the interaction and suggest that a revision of the existing concept is necessary.Similarly.observed variability in the torus indicates the presence of complex plasma processes which at present remain unexplained.Areas where further research is necessary are outlined.
文摘A new theoretical prediction that a plasma can produce antineutrinos is used to solve the solar neutrino problem. The difference between electron-positron induced fusion, and inertial fusion experiments that have been unsuccessful so far as commercial fusion reactors is also discussed.
基金This project was financially supported by the National Science Foundation of Beijing, China (No.04D063)
文摘Hetero-junction solar cells with an mc-Si:H window layer were achieved. The open voltage is increased while short current is decreased with increasing the mc-Si:H layer′s thickness of emitter layer. The highest of Voc of 597 mV has obtained. When fixed the thickness of 30 nm, changing the N type from amorphous silicon layer to micro-crystalline layer, the efficiency of the hetero-junction solar cells is increased. Although the hydrogen etching before deposition enables the c-Si substrates to become rough by AFM images, it enhances the formation of epitaxial-like micro-crystalline silicon and better parameters of solar cell can be obtained by implying this process. The best result of efficiency is 13.86% with the Voc of 549.8 mV, Jsc of 32.19 mA·cm-2 and the cell′s area of 1 cm2.
文摘This paper calculates the redshift of the 2292 MHz radio photon emitted by the Pioneer-6 space probe. The signal crossed the solar corona on the days close to the solar occultation between November and December 1968, the only ones for which scientific data are available, until it reached a terrestrial radio receiver. The specific study is based on a calculated orbital model of the Earth and Pioneer-6 system made on a scale of 1:100,000 by a CAD, on the New Tired Light theory adapted to the geometric and physical configuration of the topic and on a computational method. Removing the Doppler shift contributions of proper and rotational motions, due to the set-up of the receiver, and excluding the recombination factor of neutral hydrogen, which is irrelevant for distances within 1 AU, the calculation of the redshift can be traced back to the interactions between the radio signal and the electrons of the solar corona alone. The latter are contained in a Stroemgren sphere and photo-ionized by solar radiation in the UV and X-ray range. Furthermore, in order to have an interactional redshift contribution, the electrons have to satisfy the Wigner-Crystal Precondition for which their unitary potential energy is greater than their kinetic energy. Otherwise, a Thomson scattering process takes place in which the energy of the radio photon remains unchanged. The comparison between the gravitational redshift together with the interactional redshift detected from this study methodology and the total redshift obtained from other scientific studies shows a similarity between the curves, including the observational data, both in terms of values, trend of the graphs and single punctual variations.
文摘A novel theory of acoustics in solar energy supporting the principle of source and sink of solar energy is presented. The significance of the theory is in ascertaining the aftermaths of turning off solar energy. An amplifier constituting of a parallel plate photovoltaic device connected to a potentiometer is illustrated. It was constructed with a pair of glass coated photovoltaic modules and polystyrene filled plywood board as back panel with air ventilation through a parallel plate channel of amplifier. The sample results obtained from experiments and simulation model are presented to support hypothesis of acoustics for a parallel plate photovoltaic device connected to a potentiometer. A phenomenon of photovoltaic amplification is formulated.