As one of the major volatile components in extraterrestrial materials,nitrogen(N_(2))isotopes serve not only as tracers for the formation and evolution of the solar system,but also play a critical role in assessing pl...As one of the major volatile components in extraterrestrial materials,nitrogen(N_(2))isotopes serve not only as tracers for the formation and evolution of the solar system,but also play a critical role in assessing planetary habitability and the search for extraterrestrial life.The integrated measurement of N_(2)and argon(Ar)isotopes by using noble gas mass spectrometry represents a state-of-the-art technique for such investigations.To support the growing demands of planetary science research in China,we have developed a high-efficiency,high-precision method for the integrated analysis of N_(2)and Ar isotopes.This was achieved by enhancing gas extraction and purification systems and integrating them with a static noble gas mass spectrometer.This method enables integrated N_(2)-Ar isotope measurements on submilligram samples,significantly improving sample utilization and reducing the impact of sample heterogeneity on volatile analysis.The system integrates CO_(2)laser heating,a modular two-stage Zr-Al getter pump,and a CuO furnace-based purification process,effectively reducing background levels(N_(2)blank as low as 0.35×10^(−6)cubic centimeters at standard temperature and pressure[ccSTP]).Analytical precision is ensured through calibration with atmospheric air and CO corrections.To validate the reliability of the method,we performed N_(2)-Ar isotope analyses on the Allende carbonaceous chondrite,one of the most extensively studied meteorites internationally.The measured N_(2)concentrations range from 19.2 to 29.8 ppm,withδ15N values between−44.8‰and−33.0‰.Concentrations of 40Ar,36Ar,and 38Ar are(12.5-21.1)×10^(−6)ccSTP/g,(90.9-150.3)×10^(−9)ccSTP/g,and(19.2-30.7)×10^(−9)ccSTP/g,respectively.These values correspond to cosmic-ray exposure ages of 4.5-5.7 Ma,consistent with previous reports.Step-heating experiments further reveal distinct release patterns of N and Ar isotopes,as well as their associations with specific mineral phases in the meteorite.In summary,the combined N_(2)-Ar isotopic system offers significant advantages for tracing volatile sources in extraterrestrial materials and will provide essential analytical support for upcoming Chinese planetary missions,such as Tianwen-2.展开更多
The interfacial properties of Schottky contacts crucially affect the performance of power devices. While a few studies have explored the impact of fluorine on Schottky contacts, a comprehensive theoretical explanation...The interfacial properties of Schottky contacts crucially affect the performance of power devices. While a few studies have explored the impact of fluorine on Schottky contacts, a comprehensive theoretical explanation supported by experimental evidence remains lacking. This work investigates the effects of fluorine incorporation and electrothermal annealing(ETA) on the current transport process at Ni/β-Ga_(2)O_(3) Schottky contacts. X-ray photoelectron spectroscopy and first-principles calculations confirm the presence of fluorine substitutions for oxygen and oxygen vacancies and their lowering effect on the Schottky barrier heights. Additionally, accurate electrothermal hybrid TCAD simulations validates the extremely short-duration high temperatures(683 K) induced by ETA, which facilitates lattice rearrangement and reduces interface trap states. The interface trap states are quantitatively resolved through frequency-dependent conductance technique, showing the trap density(DT)reduction from(0.88-2.48) × 10^(11) cm^(-2)·eV^(-1) to(0.46-2.09) × 10^(11) cm^(-2)·eV^(-1). This investigation offers critical insights into the β-Ga_(2)O_(3) contacts with the collaborative treatment and solids the promotion of high-performance β-Ga_(2)O_(3) power devices.展开更多
A laser lap welding process for zinc-coated steel has a well-known unsolved problem-porosity formation. The boiling temperature of coated zinc is lower than the melting temperature of the base metal, which is steel. I...A laser lap welding process for zinc-coated steel has a well-known unsolved problem-porosity formation. The boiling temperature of coated zinc is lower than the melting temperature of the base metal, which is steel. In the autogenous laser welding, the zinc vapor generates from the lapped surfaces expels the molten pool and the expulsion causes numerous weld defects, such as spatters and blow holes on the weld surface and porosity inside the welds. The laser-arc hybrid welding was suggested as an alternative method for the laser lap welding because the arc can preheat or post-beat the weldment according to the arrangement of the laser beam and the arc. CO2 laser-micro plasma hybrid welding was applied to the lap welding of zinc-coated steel with zero-gap. The relationships among the weld quality and process parameters of the laser-arc arrangement, and the laser-arc interspacing distance and arc current were investigated using a full-factorial experimental design. The effect of laser-arc arrangement is dominant because the leading plasma arc partially melts the upper steel sheets and vaporizes or oxidizes the coated zinc on the lapped surfaces. Compared with the result from the laser-TIG hybrid welding, the heat input from arc can be reduced by 40%.展开更多
A key problem in CO_2 conversion by thermal plasma is suppressing the inverse reactions,CO?+?O?→?CO_2 and CO?+?0.5O_2?→?CO_2, to simultaneously obtain high CO yield and energy efficiency. This can be done by quickly...A key problem in CO_2 conversion by thermal plasma is suppressing the inverse reactions,CO?+?O?→?CO_2 and CO?+?0.5O_2?→?CO_2, to simultaneously obtain high CO yield and energy efficiency. This can be done by quickly quenching the decomposed gas or rapidly taking away free oxygen from decomposed gas. In this paper, experiments of CO_2 conversion by thermal plasma with carbon as a reducing agent are presented. Carbon quickly devoured free oxygen in thermal plasma decomposed gas, and not only is the inverse reaction completely suppressed, but the discharge energy to form oxygen atoms, oxygen molecular, and thermal energy is also reused.A CO_2 conversion rate of 67%–94% and the corresponding electric energy efficiency of about 70% are achieved, both are much higher than that seen so far by other plasma implementations.展开更多
CO2 methanation has been a hot topic because of its important application in the spacecraft and potential utilization of carbon dioxide. Nickel catalyst is active for this reaction. However, its activity still needs t...CO2 methanation has been a hot topic because of its important application in the spacecraft and potential utilization of carbon dioxide. Nickel catalyst is active for this reaction. However, its activity still needs to be improved. Dielectric barrier discharge （DBD） plasma, initiated at ambient condition and operated at -150 ℃, has been employed in this work for decomposition of nickel precursor to prepare Ni/MgAl2O4. The plasma decomposition results in high dispersion, unique structure, enhanced reducibility of Ni particles and promoted catalyst-support interaction. An improved activity of CO2 methanation with a higher yield of methane has been achieved over the plasma decomposed catalyst, compared to the catalyst prepared thermally. For example, the methane yield of the plasma prepared catalyst is 71.8% at 300 ℃ but it is 62.9% over the thermal prepared catalyst. The catalyst characterization confirmed that CO2 methanation over the DBD plasma prepared catalyst follows pathway of CO methanation.展开更多
In this paper, a high-speed camera and an optical emission monitor were used to study the behavior of vapor/ plasma during CO2 laser welding of SUS304 stainless steel. Results of optical emission from vapor/plasma sho...In this paper, a high-speed camera and an optical emission monitor were used to study the behavior of vapor/ plasma during CO2 laser welding of SUS304 stainless steel. Results of optical emission from vapor/plasma show that two characteristic frequency bands exist, 100 -500 Hz and 1 500 -3 500 Hz. At the same time, the changing images of vapor/ plasma and bottom pool also confirm that there are two different fluctuation frequency bands. One of the frequency bands represents the characteristic of vapor/plasma within the keyhole, and it is within 167 -500 Hz. Another frequency band is within 1 500 - 3 500 Hz, and it obviously derives from the shielding gas. Some factors may cause these frequency differences between the keyhole plasma and the shielding gas plasma. One of them is that the vapor/plasma pressure within the keyhole will increase slowly.展开更多
CO2 pyrolysis by thermal plasma was investigated,and a high conversion rate of 33% and energy efficiency of 17% were obtained.The high performance benefited from a novel quenching method,which synergizes the convergin...CO2 pyrolysis by thermal plasma was investigated,and a high conversion rate of 33% and energy efficiency of 17% were obtained.The high performance benefited from a novel quenching method,which synergizes the converging nozzle and cooling tube.To understand the synergy effect,a computational fluid dynamics simulation was carried out.A quick quenching rate of 10~7Ks（-1） could be expected when the pyrolysis gas temperature decreased from more than 3000 to 1000 K.According to the simulation results,the quenching mechanism was discussed as follows： first,the compressible fluid was adiabatically expanded in the converging nozzle and accelerated to sonic speed,and parts of the heat energy converted to convective kinetic energy; second,the sonic fluid jet into the cooling tube formed a strong eddy,which greatly enhanced the heat transfer between the inverse-flowing fluid and cooling tube.These two mechanisms ensure a quick quenching to prevent the reverse reaction of CO2 pyrolysis gas when it flows out from the thermal plasma reactor.展开更多
In this paper, the conversion of CO2/CH4 by using pulse corona plasma was studied at atmospheric pressure and ambient temperature. The effects of ratio of CO2/CH4, pulse voltage and repeated frequency of plasma discha...In this paper, the conversion of CO2/CH4 by using pulse corona plasma was studied at atmospheric pressure and ambient temperature. The effects of ratio of CO2/CH4, pulse voltage and repeated frequency of plasma discharge were first studied in the system.展开更多
Results in the air-breathing propulsion experiments with a parabolic light craft and a self-made UV-preionized 100 J TEA CO2 laser device are presented. Air disturbance and the spectrum of the plasma after the interac...Results in the air-breathing propulsion experiments with a parabolic light craft and a self-made UV-preionized 100 J TEA CO2 laser device are presented. Air disturbance and the spectrum of the plasma after the interaction of pulsed laser radiation with the light craft were studied. It was found that the focal length of the parabolic light craft had a significant effect on the air-disturbance. Two shock waves were detected for the longer focal length, while only one shock wave detected for the short focal length. The spectrum of the laser-induced plasma, the distribution of the characteristic lines, and the temporal behaviors of the air plasma were studied in detail. The results showed that, the evolution of the laser-induced plasma lasted 20μs, and the plasma spectrum would reach the maximum intensity at 7μs.展开更多
This paper presents a brief overview of CO2 reforming of CH4 （CRM） by various forms of ＂arc＂ plasma, which is more suitable to CRM, and the energy efficiency is used to evaluate different plasma processes specific...This paper presents a brief overview of CO2 reforming of CH4 （CRM） by various forms of ＂arc＂ plasma, which is more suitable to CRM, and the energy efficiency is used to evaluate different plasma processes specifically. According to the reported results, the arc thermal plasma with binode exhibited better performance. Moreover, the plasma CRM process was compared with the reported plasma steam reforming of CH4 （SRM） process, and the results showed that the former process has advantages on energy efficiency and CH4 consumption. Additionally, it is believed that the plasma CRM process would be competitive with the conventional SRM process in both energy efficiency and CO2 emission once the heat management is emphasized and the renewable power is used. Finally, a concept of plasma reactor for industrial application is proposed.展开更多
In this study,spectroscopic measurements of CO2- Ar arc plasma flow are conducted using a hollow electrode arc heated wind tunnel. In CO2- Ar plasma,radiation of C2 Swan band system is predominant. Other molecular and...In this study,spectroscopic measurements of CO2- Ar arc plasma flow are conducted using a hollow electrode arc heated wind tunnel. In CO2- Ar plasma,radiation of C2 Swan band system is predominant. Other molecular and atomic spectra are not observed except Cu spectra which are produced due to the electrode melting. Background continuum radiation is observed and overlapped with C2 Swan band system. Temperature evaluation of CO2- Ar arc plasma flow is conducted by the area intensity method and temperature distribution is obtained along the stagnation streamline around a disk model. It is found that the vibrational temperature is much higher than the rotational temperature in the free stream region due to the vibrational nonequilibrium process. In the shock layer,the rotational temperature increases by about 1 000 K while the vibrational temperature decreases by about 1 000 K. Energy exchange between translation and vibration modes is activated in the shock layer,resulting in the decrease of the vibrational temperature. However,the vibrational temperature is still higher than the rotational temperature,indicating that the vibrational relaxation process is not completed. In conclusion,the thermochemical state of the CO2- Ar arc plasma flow is in the vibrational nonequilibrium state along the stagnation streamline around the disk model.展开更多
基金supported by the Bureau of Frontier Sciences and Basic Research,Chinese Academy of Sciences(Grant No.QYJ-2025-0103)the National Natural Science Foundation of China(Grant Nos.42441834,42241105,42441825,and 42203048)the Key Research Program of the Institute of Geology and Geophysics,Chinese Academy of Sciences(Grant No.IGGCAS-202401).
文摘As one of the major volatile components in extraterrestrial materials,nitrogen(N_(2))isotopes serve not only as tracers for the formation and evolution of the solar system,but also play a critical role in assessing planetary habitability and the search for extraterrestrial life.The integrated measurement of N_(2)and argon(Ar)isotopes by using noble gas mass spectrometry represents a state-of-the-art technique for such investigations.To support the growing demands of planetary science research in China,we have developed a high-efficiency,high-precision method for the integrated analysis of N_(2)and Ar isotopes.This was achieved by enhancing gas extraction and purification systems and integrating them with a static noble gas mass spectrometer.This method enables integrated N_(2)-Ar isotope measurements on submilligram samples,significantly improving sample utilization and reducing the impact of sample heterogeneity on volatile analysis.The system integrates CO_(2)laser heating,a modular two-stage Zr-Al getter pump,and a CuO furnace-based purification process,effectively reducing background levels(N_(2)blank as low as 0.35×10^(−6)cubic centimeters at standard temperature and pressure[ccSTP]).Analytical precision is ensured through calibration with atmospheric air and CO corrections.To validate the reliability of the method,we performed N_(2)-Ar isotope analyses on the Allende carbonaceous chondrite,one of the most extensively studied meteorites internationally.The measured N_(2)concentrations range from 19.2 to 29.8 ppm,withδ15N values between−44.8‰and−33.0‰.Concentrations of 40Ar,36Ar,and 38Ar are(12.5-21.1)×10^(−6)ccSTP/g,(90.9-150.3)×10^(−9)ccSTP/g,and(19.2-30.7)×10^(−9)ccSTP/g,respectively.These values correspond to cosmic-ray exposure ages of 4.5-5.7 Ma,consistent with previous reports.Step-heating experiments further reveal distinct release patterns of N and Ar isotopes,as well as their associations with specific mineral phases in the meteorite.In summary,the combined N_(2)-Ar isotopic system offers significant advantages for tracing volatile sources in extraterrestrial materials and will provide essential analytical support for upcoming Chinese planetary missions,such as Tianwen-2.
基金supported by the National Natural Science Foundation of China (Grant Nos. 62174019, 52302046, L2424216)the Guangdong Basic and Applied Basic Research Foundation (Grant No. 2024A1515012139)+2 种基金the Major Program (JD) of Hubei Province (Grant No. 2023BAA009)the Knowledge Innovation Program of Wuhan-Shuguang Project (Grant No. 2023010201020262)the Basic Research Program of Jiangsu (Grant No. BK20230268)。
文摘The interfacial properties of Schottky contacts crucially affect the performance of power devices. While a few studies have explored the impact of fluorine on Schottky contacts, a comprehensive theoretical explanation supported by experimental evidence remains lacking. This work investigates the effects of fluorine incorporation and electrothermal annealing(ETA) on the current transport process at Ni/β-Ga_(2)O_(3) Schottky contacts. X-ray photoelectron spectroscopy and first-principles calculations confirm the presence of fluorine substitutions for oxygen and oxygen vacancies and their lowering effect on the Schottky barrier heights. Additionally, accurate electrothermal hybrid TCAD simulations validates the extremely short-duration high temperatures(683 K) induced by ETA, which facilitates lattice rearrangement and reduces interface trap states. The interface trap states are quantitatively resolved through frequency-dependent conductance technique, showing the trap density(DT)reduction from(0.88-2.48) × 10^(11) cm^(-2)·eV^(-1) to(0.46-2.09) × 10^(11) cm^(-2)·eV^(-1). This investigation offers critical insights into the β-Ga_(2)O_(3) contacts with the collaborative treatment and solids the promotion of high-performance β-Ga_(2)O_(3) power devices.
文摘A laser lap welding process for zinc-coated steel has a well-known unsolved problem-porosity formation. The boiling temperature of coated zinc is lower than the melting temperature of the base metal, which is steel. In the autogenous laser welding, the zinc vapor generates from the lapped surfaces expels the molten pool and the expulsion causes numerous weld defects, such as spatters and blow holes on the weld surface and porosity inside the welds. The laser-arc hybrid welding was suggested as an alternative method for the laser lap welding because the arc can preheat or post-beat the weldment according to the arrangement of the laser beam and the arc. CO2 laser-micro plasma hybrid welding was applied to the lap welding of zinc-coated steel with zero-gap. The relationships among the weld quality and process parameters of the laser-arc arrangement, and the laser-arc interspacing distance and arc current were investigated using a full-factorial experimental design. The effect of laser-arc arrangement is dominant because the leading plasma arc partially melts the upper steel sheets and vaporizes or oxidizes the coated zinc on the lapped surfaces. Compared with the result from the laser-TIG hybrid welding, the heat input from arc can be reduced by 40%.
基金the supports of National Natural Science Foundation of China (Nos. 11775155, 51561135013, 21603202)
文摘A key problem in CO_2 conversion by thermal plasma is suppressing the inverse reactions,CO?+?O?→?CO_2 and CO?+?0.5O_2?→?CO_2, to simultaneously obtain high CO yield and energy efficiency. This can be done by quickly quenching the decomposed gas or rapidly taking away free oxygen from decomposed gas. In this paper, experiments of CO_2 conversion by thermal plasma with carbon as a reducing agent are presented. Carbon quickly devoured free oxygen in thermal plasma decomposed gas, and not only is the inverse reaction completely suppressed, but the discharge energy to form oxygen atoms, oxygen molecular, and thermal energy is also reused.A CO_2 conversion rate of 67%–94% and the corresponding electric energy efficiency of about 70% are achieved, both are much higher than that seen so far by other plasma implementations.
基金supported by the National Natural Science Foundation of China(under contracts#21476157 and#21406177)
文摘CO2 methanation has been a hot topic because of its important application in the spacecraft and potential utilization of carbon dioxide. Nickel catalyst is active for this reaction. However, its activity still needs to be improved. Dielectric barrier discharge （DBD） plasma, initiated at ambient condition and operated at -150 ℃, has been employed in this work for decomposition of nickel precursor to prepare Ni/MgAl2O4. The plasma decomposition results in high dispersion, unique structure, enhanced reducibility of Ni particles and promoted catalyst-support interaction. An improved activity of CO2 methanation with a higher yield of methane has been achieved over the plasma decomposed catalyst, compared to the catalyst prepared thermally. For example, the methane yield of the plasma prepared catalyst is 71.8% at 300 ℃ but it is 62.9% over the thermal prepared catalyst. The catalyst characterization confirmed that CO2 methanation over the DBD plasma prepared catalyst follows pathway of CO methanation.
文摘In this paper, a high-speed camera and an optical emission monitor were used to study the behavior of vapor/ plasma during CO2 laser welding of SUS304 stainless steel. Results of optical emission from vapor/plasma show that two characteristic frequency bands exist, 100 -500 Hz and 1 500 -3 500 Hz. At the same time, the changing images of vapor/ plasma and bottom pool also confirm that there are two different fluctuation frequency bands. One of the frequency bands represents the characteristic of vapor/plasma within the keyhole, and it is within 167 -500 Hz. Another frequency band is within 1 500 - 3 500 Hz, and it obviously derives from the shielding gas. Some factors may cause these frequency differences between the keyhole plasma and the shielding gas plasma. One of them is that the vapor/plasma pressure within the keyhole will increase slowly.
基金the funding of National Natural Science Foundation of China (Grant No.11775155)
文摘CO2 pyrolysis by thermal plasma was investigated,and a high conversion rate of 33% and energy efficiency of 17% were obtained.The high performance benefited from a novel quenching method,which synergizes the converging nozzle and cooling tube.To understand the synergy effect,a computational fluid dynamics simulation was carried out.A quick quenching rate of 10~7Ks（-1） could be expected when the pyrolysis gas temperature decreased from more than 3000 to 1000 K.According to the simulation results,the quenching mechanism was discussed as follows： first,the compressible fluid was adiabatically expanded in the converging nozzle and accelerated to sonic speed,and parts of the heat energy converted to convective kinetic energy; second,the sonic fluid jet into the cooling tube formed a strong eddy,which greatly enhanced the heat transfer between the inverse-flowing fluid and cooling tube.These two mechanisms ensure a quick quenching to prevent the reverse reaction of CO2 pyrolysis gas when it flows out from the thermal plasma reactor.
文摘In this paper, the conversion of CO2/CH4 by using pulse corona plasma was studied at atmospheric pressure and ambient temperature. The effects of ratio of CO2/CH4, pulse voltage and repeated frequency of plasma discharge were first studied in the system.
基金National Key Basic Research Special Foundation of China
文摘Results in the air-breathing propulsion experiments with a parabolic light craft and a self-made UV-preionized 100 J TEA CO2 laser device are presented. Air disturbance and the spectrum of the plasma after the interaction of pulsed laser radiation with the light craft were studied. It was found that the focal length of the parabolic light craft had a significant effect on the air-disturbance. Two shock waves were detected for the longer focal length, while only one shock wave detected for the short focal length. The spectrum of the laser-induced plasma, the distribution of the characteristic lines, and the temporal behaviors of the air plasma were studied in detail. The results showed that, the evolution of the laser-induced plasma lasted 20μs, and the plasma spectrum would reach the maximum intensity at 7μs.
基金supported by National Natural Science Foundation of China(No.11375123)the Research Project of Xuzhou Institute of Technology,China(No.XKY2015308)
文摘This paper presents a brief overview of CO2 reforming of CH4 （CRM） by various forms of ＂arc＂ plasma, which is more suitable to CRM, and the energy efficiency is used to evaluate different plasma processes specifically. According to the reported results, the arc thermal plasma with binode exhibited better performance. Moreover, the plasma CRM process was compared with the reported plasma steam reforming of CH4 （SRM） process, and the results showed that the former process has advantages on energy efficiency and CH4 consumption. Additionally, it is believed that the plasma CRM process would be competitive with the conventional SRM process in both energy efficiency and CO2 emission once the heat management is emphasized and the renewable power is used. Finally, a concept of plasma reactor for industrial application is proposed.
文摘In this study,spectroscopic measurements of CO2- Ar arc plasma flow are conducted using a hollow electrode arc heated wind tunnel. In CO2- Ar plasma,radiation of C2 Swan band system is predominant. Other molecular and atomic spectra are not observed except Cu spectra which are produced due to the electrode melting. Background continuum radiation is observed and overlapped with C2 Swan band system. Temperature evaluation of CO2- Ar arc plasma flow is conducted by the area intensity method and temperature distribution is obtained along the stagnation streamline around a disk model. It is found that the vibrational temperature is much higher than the rotational temperature in the free stream region due to the vibrational nonequilibrium process. In the shock layer,the rotational temperature increases by about 1 000 K while the vibrational temperature decreases by about 1 000 K. Energy exchange between translation and vibration modes is activated in the shock layer,resulting in the decrease of the vibrational temperature. However,the vibrational temperature is still higher than the rotational temperature,indicating that the vibrational relaxation process is not completed. In conclusion,the thermochemical state of the CO2- Ar arc plasma flow is in the vibrational nonequilibrium state along the stagnation streamline around the disk model.
