Recent experiments at the National Ignition Facility and theoretical modeling suggest that side stimulated Raman scattering(SSRS)instability could reduce laser–plasma coupling and generate considerable fluxes of supr...Recent experiments at the National Ignition Facility and theoretical modeling suggest that side stimulated Raman scattering(SSRS)instability could reduce laser–plasma coupling and generate considerable fluxes of suprathermal hot electrons under interaction conditions envisaged for direct-drive schemes for inertial confinement fusion.Nonetheless,SSRS remains to date one of the least understood parametric instabilities.Here,we report the first angularly and spectrally resolved measurements of scattered light at laser intensities relevant for the shock ignition scheme(I×10^(16)W/cm^(2)),showing significant SSRS growth in the direction perpendicular to the laser polarization.Modification of the focal spot shape and orientation,obtained by using two different random phase plates,and of the density gradient of the plasma,by utilizing exploding foil targets of different thicknesses,clearly reveals a different dependence of backward SRS(BSRS)and SSRS on experimental parameters.While convective BSRS scales with plasma density scale length,as expected by linear theory,the growth of SSRS depends on the spot extension in the direction perpendicular to laser polarization.Our analysis therefore demonstrates that under current experimental conditions,with density scale lengths L_(n)≈60–120μm and spot sizes FWHM≈40–100μm,SSRS is limited by laser beam size rather than by the density scale length of the plasma.展开更多
Researches on plasma-facing materials/components(PFMs/PFCs)have become a focus in magnetic confinement fusion studies,particularly for advanced tokamak operation scenarios.Similarly,spacecraft surface materials must m...Researches on plasma-facing materials/components(PFMs/PFCs)have become a focus in magnetic confinement fusion studies,particularly for advanced tokamak operation scenarios.Similarly,spacecraft surface materials must maintain stable performance under relatively high temperatures and other harsh plasma conditions,making studies of their thermal and ablation resistance critical.Recently,a low-cost,low-energy-storage for superconducting magnets,and compact linear device,HIT-PSI,has been designed and constructed at Harbin Institute of Technology(HIT)to investigate the interaction between stable high heat flux plasma and PFMs/PFCs in scrape-off-layer(SOL)and divertor regions,as well as spacecraft surface materials.The parameters of the argon plasma beam of HIT-PSI are diagnosed using a water-cooled planar Langmuir probe and emission spectroscopy.As magnetic field rises to 2 T,the argon plasma beam generated by a cascaded arc source achieves high density exceeding 1.2×10^(21)m^(-3)at a distance of 25 cm from the source with electron temperature surpassing 4 eV,where the particle flux reaches 10^(24)m^(-2)s^(-1),and the heat flux loaded on the graphite target measured by infrared camera reaches 4 MW/m^(2).Combined with probe and emission spectroscopy data,the transport characteristics of the argon plasma beam are analyzed.展开更多
Plasma treatment is necessary to optimize the performance of biomaterial surfaces.It enhances and regulates the performance of biomaterial su rfaces,creating an effective interface with the human body.Plasma treatment...Plasma treatment is necessary to optimize the performance of biomaterial surfaces.It enhances and regulates the performance of biomaterial su rfaces,creating an effective interface with the human body.Plasma treatments have the ability to modify the chemical com position and physical structu re of a surface while leaving its properties unaffected.They possess the ability to modify material su rfaces,eliminate contaminants,conduct investigations on cancer therapy,and facilitate wound healing.The subject of study in question involves the integration of plasma science and technology with biology and medicine.Using a helium plasma jet source,applying up to 18 kV,with an average power of 10 W,polymer foils were treated for 60 s.Plasma treatment has the ability to alter the chemical composition and physical structure of a su rface while maintaining its quality.This investigation involved the application of helium plasma at atmospheric pressure to polyamide 6 and polyethylene terephthalate sheets.The inquiry involves monitoring and assessing the plasma source and polymer materials,as well as analyzing the impacts of plasma therapy.Calculating the mean power of the discharge aids in assessing the economic efficacy of the plasma source.Electric discharge in helium at atmospheric pressure has beneficial effects in technology,where it increases the surface free energy of polymer materials.In biomedicine,it is used to investigate cytotoxicity and cell survival,particularly in direct blood exposure situations that can expedite coagulation.Comprehending the specific parameters that influence the plasma source in the desired manner for the intended application is of utmost im portance.展开更多
A plasma column excited by a surface wave can act as a plasma antenna. Experiments are carried out to study the current and conductivity distributions, field, power patterns, directivity and efficiency of such a plasm...A plasma column excited by a surface wave can act as a plasma antenna. Experiments are carried out to study the current and conductivity distributions, field, power patterns, directivity and efficiency of such a plasma antenna. In addition, an equivalent metallic copper antenna is built up and its antenna parameters are compared with that of the plasma antenna. Our findings indicate that the power content in the harmonics of the plasma antenna is more prominent as compared to the copper antenna （which only generates a fundamental frequency）. However, the power patterns for both antennae are quite similar. To provide a more qualitative understanding regarding the generation of harmonics in the field of the plasma antenna, a bi-spectral analysis is performed to study the nonlinear interactions in the current fluctuations. Some specific features of the plasma antenna are investigated in our study, which may enhance the application prospect of the plasma antenna with respect to the conventional metallic antenna.展开更多
Coaxial plasma guns are a type of plasma source that produces plasma which propagates radially and axially controlled by the shape of the ground electrode, which has attracted much interest in several applications. In...Coaxial plasma guns are a type of plasma source that produces plasma which propagates radially and axially controlled by the shape of the ground electrode, which has attracted much interest in several applications. In this work, a 120° opening angle of CPG nozzle is used as a plasma gun configuration that operates at the energy of 150 J. The ionization of polyethylene insulator between the electrodes of the gun produces a cloud of hydrogen and carbon plasma.The triple Langmuir probe and Faraday cup are used to measure plasma density and plasma temperature. These methods are used to measure the on-axis and off-axis plasma divergence of the coaxial plasma gun. The peak values of ion densities measured at a distance of 25 mm on-axis from the plasma gun are(1.6±0.5)×10^(19)m^(-3)and(2.8±0.6)×10^(19)m^(-3)for hydrogen and carbon plasma respectively and the peak temperature is 3.02±0.5 eV. The mean propagation velocity of plasma is calculated using the transit times of plasma at different distances from the plasma gun and is found to be 4.54±0.25 cm/μs and 1.81±0.18 cm/μs for hydrogen and carbon plasma respectively. The Debye radius is obtained from the measured experimental data that satisfies the thin sheath approximation. The shot-to-shot stability of plasma parameters facilitates the use of plasma guns in laboratory experiments. These types of plasma sources can be used in many applications like plasma opening switches, plasma devices, and as plasma sources.展开更多
A simple method for measuring RF plasma parameters by means of a DC-biased Langmuir probe is developed. The object of this paper is to ensure the reliability of this method by using the other methods with different pr...A simple method for measuring RF plasma parameters by means of a DC-biased Langmuir probe is developed. The object of this paper is to ensure the reliability of this method by using the other methods with different principles. First, Langmuir probe current response on RF voltage superimposed to DC biased probe was examined in DC plasmas. Next, probe current response of DC biased probe in RF plasmas was studied and compared with the first experiment. The results were confirmed by using an emissive prove method, an ion acoustic wave method, and a square pulse response method. The method using a simple Langmuir probe is useful and convenient for measuring electron temperature , electron density , time-averaged space potential , and amplitude of space potential oscillation in RF plasmas with a frequency of the order of .展开更多
The dual cylindrical inductively coupled plasma source,compared to the conventional structure of inductively coupled plasma source,can significantly improve the uniformity of plasma.It has an enhanced potential for ap...The dual cylindrical inductively coupled plasma source,compared to the conventional structure of inductively coupled plasma source,can significantly improve the uniformity of plasma.It has an enhanced potential for application in processes,such as etching and ashing.A uniform plasma can be obtained by allowing the remote plasma from the upper chamber modulate the main plasma generated in the lower chamber.In this study,a fluid model was employed to investigate a dual cylindrical inductively coupled Ar/O_(2)discharge.The effects of external parameters on electron density,electron temperature,O atomic density,and plasma uniformity in the main chamber were studied,and the reasons were analyzed.The results of this study show that remote power can control the plasma uniformity and increase the plasma density in the main chamber.As the remote power increased,plasma uniformity improved initially and then deteriorated.The main power affected the plasma density at the edge of the main chamber and can modulate the plasma density in the main chamber.The gas pressure affected both the uniformity and density of the plasma.As the gas pressure increased,the plasma uniformity deteriorated,but the free radical density improved.展开更多
In this experimental prospective study, we aimed to analyze the effect of transient scrotal hyperthermia on the male reproductive organs, from the perspective of sperm parameters, semen plasma biochemical markers, and...In this experimental prospective study, we aimed to analyze the effect of transient scrotal hyperthermia on the male reproductive organs, from the perspective of sperm parameters, semen plasma biochemical markers, and oxidative stress, to evaluate whether different frequencies of heat exposure cause different degrees of damage to spermatogenesis. Two groups of volunteers （10 per group） received testicular warming in a 43~C water bath 10 times, for 30 min each time： group 1：10 consecutive days; group 2： once every 3 days. Sperm parameters, epididymis and accessory sex gland function, semen plasma oxidative stress and serum sex hormones were tested before treatment and in the 16-week recovery period after treatment. At last, we found an obvious reversible decrease in sperm concentration （P = 0.005 for Group 1 and P = 0.008 for Group 2 when the minimums were compared with baseline levels, the same below）, motility （P= 0.009 and 0.021, respectively）, the hypoosmotic swelling test score （P-- 0.007 and 0.008, respectively）, total acrosin activity （P = 0.018 and 0.009, respectively）, and an increase in the seminal plasma malondialdehyde concentration （P = 0.005 and 0.017, respectively）. The decrease of sperm concentration was greater for Group 2 than for Group 1 （P = 0.031）. We concluded that transient scrotal hyperthermia seriously, but reversibly, negatively affected the spermatogenesis, oxidative stress may be involved in this process. In addition, intermittent heat exposure more seriously suppresses the spermatogenesis compared to consecutive heat exposure. This may be indicative for clinical infertility etiology analysis and the design of contraceptive methods based on heat stress.展开更多
Laser Induced Breakdown Spectroscopic(LIBS)technique was used to detect calcium and silicon in an unknown sample.In this method plasma was generated by Nd∶YAG laser of wavelength 1 064 nm with energy 400 mJ and pulse...Laser Induced Breakdown Spectroscopic(LIBS)technique was used to detect calcium and silicon in an unknown sample.In this method plasma was generated by Nd∶YAG laser of wavelength 1 064 nm with energy 400 mJ and pulse duration between 5~10ns.The method was applied for the qualitative as well as quantitative analysis.In the qualitative analysis,the electron number density(Ne)of plasma containing calcium and silicon is determined showing that Neof neutral particles is equivalent to 1016(cm-3)whereas for ionized particles it is 1017(cm-3).Plasma temperature is measured using Boltzmann plot method which must be greater than 10 000 k.Intensity ratio method is used for the quantitative analysis shows various elements in abundance with calcium and silicon in majority.展开更多
Ni-based composite coatings with a high content of tungsten carbides(Stelcar65composite coatings)were synthesized by plasma transferred arc(PTA)hardfacing.The welding parameters of Stelcar65composite coatings were opt...Ni-based composite coatings with a high content of tungsten carbides(Stelcar65composite coatings)were synthesized by plasma transferred arc(PTA)hardfacing.The welding parameters of Stelcar65composite coatings were optimized by orthogonal tests.The PTA welding parameters including welding current,powder feed rate and welding speed have significant influence on the tungsten carbide degradation.The values for the optimum welding current,powder feed rate and welding speed were determined to be100A,25g/min and40mm/min,respectively.The produced WC/Ni-based composite coatings were crack-and degradation-free.The microstructure of deposited layers,as well as the microstructure and microhardness of the optimal coating were further analyzed.展开更多
The geometry of an inductively coupled plasma （ICP） etcher is usually considered to be an important factor for determining both plasma and process uniformity over a large wafer. During the past few decades, these pa...The geometry of an inductively coupled plasma （ICP） etcher is usually considered to be an important factor for determining both plasma and process uniformity over a large wafer. During the past few decades, these parameters were determined by the ＂trial and error＂ method, resulting in wastes of time and funds. In this paper, a new approach of regression orthogonal design with plasma simulation experiments is proposed to investigate the sensitivity of the structural parameters on the uniformity of plasma characteristics. The tool for simulating plasma is CFD-ACE＋, which is commercial multi-physical modeling software that has been proven to be accurate for plasma simulation. The simulated experimental results are analyzed to get a regression equation on three structural parameters. Through this equation, engineers can compute the uniformity of the electron number density rapidly without modeling by CFD-ACE＋. An optimization performed at the end produces good results.展开更多
BACKGROUND Chronic obstructive pulmonary disease(COPD)is a chronic respiratory disease with worldwide occurrence and high disability and mortality rate.It occurs mostly in the elderly population with pulmonary heart d...BACKGROUND Chronic obstructive pulmonary disease(COPD)is a chronic respiratory disease with worldwide occurrence and high disability and mortality rate.It occurs mostly in the elderly population with pulmonary heart disease,type II respiratory failure,and other serious complications.AIM To investigate the correlation of plasma brain natriuretic peptide(BNP)and platelet parameters with cardiac function and pulmonary hypertension in patients with COPD and pulmonary heart disease.METHODS From June 2016 to June 2019,52 patients with COPD-pulmonary heart disease(pulmonary heart disease group),30 patients with COPD(COPD group),and 30 healthy individuals(control group)in our hospital were enrolled in the study.The pulmonary heart disease group was further divided into subgroups according to cardiac function classification and pulmonary artery pressure.Plasma BNP and platelet parameters were estimated and compared among each group and subgroup.The correlation of plasma BNP and platelet parameters with cardiac function classification and pulmonary artery pressure was then analyzed.RESULTS In the pulmonary heart disease group,the COPD group,and the control group,the levels of plasma BNP,platelet distribution width(PDW),and mean platelet volume(MPV)showed a decreasing trend(P<0.05),while an increasing trend was found in platelet count(PLT)and plateletcrit(PCT)levels among the three groups(P<0.05).In the pulmonary hypertension mild,moderate,and severe subgroups,the levels of plasma BNP,PDW,and MPV showed an increasing trend(P<0.05),while a decreasing trend was observed in PLT levels(P<0.05);however,PCT levels showed no significant difference among the three subgroups(P>0.05).In the cardiac function grade I,II,III,and IV subgroups,the levels of plasma BNP,PDW,and MPV showed an increasing trend(P<0.05),while a decreasing trend was noted in PLT and PCT levels among the four subgroups(P<0.05).Correlation analysis showed that the levels of plasma BNP,PDW,and MPV in patients with pulmonary heart disease were positively correlated with their pulmonary artery pressure(P<0.05),while PLT was negatively correlated with their pulmonary artery pressure(P<0.05).Moreover,plasma BNP,PDW,and MPV levels were positively correlated with cardiac function grade(P<0.05)of these patients,while PLT and PCT levels were negatively correlated with their cardiac function grade(P<0.05).CONCLUSION Plasma BNP and PLT parameters are significantly correlated with the cardiac function and pulmonary hypertension in patients with COPD and pulmonary heart disease,indicating that these parameters have high clinical relevance in reflecting the health condition of these patients and for guiding their treatment.展开更多
A certain amount of Ti was added to the plasma cladding Fe-Cr-C coating in the early stage in order to improve the quality and properties of the coating.Ti-Fe-Cr-C composite powder was prepared by precursor carbonizat...A certain amount of Ti was added to the plasma cladding Fe-Cr-C coating in the early stage in order to improve the quality and properties of the coating.Ti-Fe-Cr-C composite powder was prepared by precursor carbonization-composition process.In situ synthesized TiC-Fe-Cr coatings were fabricated on substrate of Q235 steel by plasma cladding process with the composite powder.Microstructures of the coatings with different process parameters,including cladding current,cladding speed,number of overlapping cladding layers,were analyzed by scanning electron microscope.The results show that the structure of the TiC-Fe-Cr coating is greatly affected by the cladding current,the cladding speed and the overlapping cladding process.In this test,when the cladding current of 300 A and the cladding process parameter of the cladding speed of 50 mm/min are clad with three layers,a well-formed and well-structured TiC-Fe-Cr coating can be obtained in this test.TiC-Fe-Cr coating has good wear resistance and good load characteristics under dry sliding wear test conditions.展开更多
Air plasma spraying process was employed to fabricate various hydroxyapatite(HA)coatings on titanium substrates.The influence of processing parameters on the phase composition and the microstructure of the obtained co...Air plasma spraying process was employed to fabricate various hydroxyapatite(HA)coatings on titanium substrates.The influence of processing parameters on the phase composition and the microstructure of the obtained coatings was investigated.The effect of heat treatment on as-sprayed coating in terms of the crystallinity and microstructure was also studied.The phase composition of coatings was analyzed by X-ray diffraction(XRD)and FTIR.The surface and cross-section morphologies and microstructure of coatings as well as the morphology of feedstock were evaluated using scanning electron microscope(SEM).The crystallization temperature of amorphous HA phase in as-sprayed coating was examined by using differential thermal analysis(DTA).The results suggest that phase composition and microstructure of as-sprayed HA coatings strongly depend on the spraying parameters,and heat treatment at 760℃for 2 h is one of effective means for increasing the crystallinity and improvement in microstructure of as-sprayed HA coatings.展开更多
Al2O3p/Al composite coatings were prepared on the surface of AZ31 magnesium alloy by plasma spraying technology with mixed powders of Al and Al2O3. An orthogonal test containing six factors and five levels was carried...Al2O3p/Al composite coatings were prepared on the surface of AZ31 magnesium alloy by plasma spraying technology with mixed powders of Al and Al2O3. An orthogonal test containing six factors and five levels was carried out to acquire the optimum technical parameters. Mierostruetures and properties of the composite coatings were studied. The results show that the coatings consist of Al2O3 particulates distributed uniformly and Al matrix, and the interface between the particulate and matrix is continuous, compact and clean. With increasing the mass fraction of Al2O3 in the mixed powders, the volume fraction of Al2O3 in the coatings iacreases. The Al2O3p/Al composite coating with 14% Al2O3 volume fraction has more compact microstrueture and more satisfactory properties.展开更多
Plasma source performance parameters, including plasma ejection density and velocity, greatly affect the operation of a short-conduction-time plasma opening switch （POS）. In this paper, the plasma source used in the...Plasma source performance parameters, including plasma ejection density and velocity, greatly affect the operation of a short-conduction-time plasma opening switch （POS）. In this paper, the plasma source used in the POS of Qiangguang I generator is chosen as the study object. At first the POS working process is analyzed. The result shows that the opening performance of the POS can be improved by increasing the plasma ejection velocity and decreasing the plasma density. The influence of the cable plasma gun structure and number on the plasma ejection parameters is experimentally investigated with two charge collectors. Finally a semi-empirical model is proposed to describe the experimental phenomenon.展开更多
Simulation of the core plasma parameters of HCSB-DEMO （helium-cooled solid breeder, HCSB）, by using a 1.5D plasma transport code, was carried out. The study includes investigations of operational scenarios, temperat...Simulation of the core plasma parameters of HCSB-DEMO （helium-cooled solid breeder, HCSB）, by using a 1.5D plasma transport code, was carried out. The study includes investigations of operational scenarios, temperature and density profiles of both ions and electrons, fusion and radiated power, distribution of the safety factor, sensitivity analyses for some input parameters as well as a primary estimate of the divertor heating load. The results indicate that the following fusion reactor parameters can be properly set for HCSB-DEMO, namely major radius of 7.2 m, aspect ratio of 3.4, elongation of 1.85, triangularity of 0.45, plasma current of 14.8 MA, normalized beta of 4.4, toroidal field （TF） of 6.86 T, average electron density of 1.5× 10^20 m^-3, average electron temperature of 14.5 keV, fusion power of 2.55 GW, neutron wall loading of 2.3 MW.m^-2 and fusion multiplication factor of 35.展开更多
Matching optimization of resonant parameters among the high power inverters,low power transformers and plasma reactors have significant effects on the performance and output of the reactor array when applying the part...Matching optimization of resonant parameters among the high power inverters,low power transformers and plasma reactors have significant effects on the performance and output of the reactor array when applying the partitioned operation method.In this paper,the Matlab/Simulink electrical model was established based on the method of partitioned operation.The matching relation between resonant parameters is analyzed on the basis of experimental result.As a consequence,transformer leakage inductance and working frequency are the important parameters influencing the operational efficiency of system,leakage inductance of transformer should be adjusted based on the equivalent capacitance of plasma reactor to realize the matching optimization of resonant parameters.展开更多
Ion parameters in electron cyclotron resonance （ECR） microwave plasma were measured by ion sensitive probe and were compared with the electron parameters obtained by double Langmuir probe. The effects of gas pressur...Ion parameters in electron cyclotron resonance （ECR） microwave plasma were measured by ion sensitive probe and were compared with the electron parameters obtained by double Langmuir probe. The effects of gas pressure and microwave power on the ion temperature and density were analyzed. The spatial distribution of the ion parameters was also investigated by the ion sensitive probes with a tunable radial depth installed on different probe windows along the chamber axis. Results showed that the ion density measured by the ion sensitive probe was in good agreement with the electron density measured by the double Langmuir probe. The influ- ence of gas pressure on the ion parameters was stronger than that of microwave power. With the increase in working pressure, the ion temperature decreased monotonously with a decreasing rate larger than that at higher pressure. The ion density first increased to a peak （42.3~ 101~ cm-3） at 1 Pa and then decreased. The ion temperature and density increased little with the increase in the microwave power from 400 W to 800 W, The plasma far away from the resonant point is found to be radially uniform.展开更多
A total of 480 nursery pigs （Duroc x Landrace x Large White） were utilized in two experiments conducted to determine the effects of different ratios of standardized ileal digestible lysine （SID- Lys） to metaboliza...A total of 480 nursery pigs （Duroc x Landrace x Large White） were utilized in two experiments conducted to determine the effects of different ratios of standardized ileal digestible lysine （SID- Lys） to metabolizable energy （ME） ratio on the performance, nutrient digestibility, plasma urea nitrogen （PUN） ,and plasma free amino acids of 10 to 28 kg pigs. In Exp. 1, 192 pigs （ 10.58 kg） were assigned to one of four treatments. The treatments consisted of diets with a ME content of 3.2, 3.25, 3.3, or 3.35 Mcal/kg with a constant SID-Lys：ME ratio of 3.7 g/Mcal. The experiment lasted 28 days. Pigs which were fed the diets containing 3.3 and 3.35 Mcal/kg ME had lower feed intakes （ P 〈 0.05）than those fed 3.2 Mcal/kg. Feed efficiency was linearly improved with increasing dietary ME （ P 〈0.05）. Increasing the dietary ME level also increased （P 〈0.05 ） dry matter and energy digestibility. Therefore,3.3 Mcal/kg ME was selected for Exp. 2 in which 288 pigs （ 10.60 kg） were assigned to one of six treatments. Treatments consisted of SID-Lys： ME ratios of 3.1,3.3,3.5,3.7,3.9, or 4.1 g/Mcal with all diets providing 3.3 Mcal of ME/kg. Weight gain and feed efficiency were increased （P 〈0.05 ） as the SID-Lys：ME ratio in diet increased. Based on a straight broken-line model ,the estimated SID-Lys：ME ratio to maximize weight gain was 3.74.展开更多
基金financial support from the LASERLAB-EUROPE Access to Research Infrastructure Activity (Application No. 23068)carried out within the framework of EUROfusion Enabling Research Projects AWP21-ENR-01-CEA02 and AWP24-ENR-IFE-02-CEA-02+3 种基金received funding from Euratom Research and Training Programme 2021–2025 under Grant No. 633053supported by the Ministry of Youth and Sports of the Czech Republic [Project No. LM2023068 (PALS RI)]by the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant Nos. XDA25030200 and XDA25010100)supported by COST (European Cooperation in Science and Technology) through Action CA21128 PROBONO (PROton BOron Nuclear Fusion: from energy production to medical applicatiOns)
文摘Recent experiments at the National Ignition Facility and theoretical modeling suggest that side stimulated Raman scattering(SSRS)instability could reduce laser–plasma coupling and generate considerable fluxes of suprathermal hot electrons under interaction conditions envisaged for direct-drive schemes for inertial confinement fusion.Nonetheless,SSRS remains to date one of the least understood parametric instabilities.Here,we report the first angularly and spectrally resolved measurements of scattered light at laser intensities relevant for the shock ignition scheme(I×10^(16)W/cm^(2)),showing significant SSRS growth in the direction perpendicular to the laser polarization.Modification of the focal spot shape and orientation,obtained by using two different random phase plates,and of the density gradient of the plasma,by utilizing exploding foil targets of different thicknesses,clearly reveals a different dependence of backward SRS(BSRS)and SSRS on experimental parameters.While convective BSRS scales with plasma density scale length,as expected by linear theory,the growth of SSRS depends on the spot extension in the direction perpendicular to laser polarization.Our analysis therefore demonstrates that under current experimental conditions,with density scale lengths L_(n)≈60–120μm and spot sizes FWHM≈40–100μm,SSRS is limited by laser beam size rather than by the density scale length of the plasma.
基金supported by National Natural Science Foundation of China(No.12105067)the ITER Organization and China Domestic Agency for the support of this work(No.ITER5.5.P01.CN.05)。
文摘Researches on plasma-facing materials/components(PFMs/PFCs)have become a focus in magnetic confinement fusion studies,particularly for advanced tokamak operation scenarios.Similarly,spacecraft surface materials must maintain stable performance under relatively high temperatures and other harsh plasma conditions,making studies of their thermal and ablation resistance critical.Recently,a low-cost,low-energy-storage for superconducting magnets,and compact linear device,HIT-PSI,has been designed and constructed at Harbin Institute of Technology(HIT)to investigate the interaction between stable high heat flux plasma and PFMs/PFCs in scrape-off-layer(SOL)and divertor regions,as well as spacecraft surface materials.The parameters of the argon plasma beam of HIT-PSI are diagnosed using a water-cooled planar Langmuir probe and emission spectroscopy.As magnetic field rises to 2 T,the argon plasma beam generated by a cascaded arc source achieves high density exceeding 1.2×10^(21)m^(-3)at a distance of 25 cm from the source with electron temperature surpassing 4 eV,where the particle flux reaches 10^(24)m^(-2)s^(-1),and the heat flux loaded on the graphite target measured by infrared camera reaches 4 MW/m^(2).Combined with probe and emission spectroscopy data,the transport characteristics of the argon plasma beam are analyzed.
基金financially supported by UEFISCDI,PNCDI III,project PN-III-P1-1.1-TE-2021(No.150/09.06.2022)supported by COST(European Cooperation in Science and Technology,available online:https://www.cost.eu,accessed on 20 November 2023)。
文摘Plasma treatment is necessary to optimize the performance of biomaterial surfaces.It enhances and regulates the performance of biomaterial su rfaces,creating an effective interface with the human body.Plasma treatments have the ability to modify the chemical com position and physical structu re of a surface while leaving its properties unaffected.They possess the ability to modify material su rfaces,eliminate contaminants,conduct investigations on cancer therapy,and facilitate wound healing.The subject of study in question involves the integration of plasma science and technology with biology and medicine.Using a helium plasma jet source,applying up to 18 kV,with an average power of 10 W,polymer foils were treated for 60 s.Plasma treatment has the ability to alter the chemical composition and physical structure of a su rface while maintaining its quality.This investigation involved the application of helium plasma at atmospheric pressure to polyamide 6 and polyethylene terephthalate sheets.The inquiry involves monitoring and assessing the plasma source and polymer materials,as well as analyzing the impacts of plasma therapy.Calculating the mean power of the discharge aids in assessing the economic efficacy of the plasma source.Electric discharge in helium at atmospheric pressure has beneficial effects in technology,where it increases the surface free energy of polymer materials.In biomedicine,it is used to investigate cytotoxicity and cell survival,particularly in direct blood exposure situations that can expedite coagulation.Comprehending the specific parameters that influence the plasma source in the desired manner for the intended application is of utmost im portance.
文摘A plasma column excited by a surface wave can act as a plasma antenna. Experiments are carried out to study the current and conductivity distributions, field, power patterns, directivity and efficiency of such a plasma antenna. In addition, an equivalent metallic copper antenna is built up and its antenna parameters are compared with that of the plasma antenna. Our findings indicate that the power content in the harmonics of the plasma antenna is more prominent as compared to the copper antenna （which only generates a fundamental frequency）. However, the power patterns for both antennae are quite similar. To provide a more qualitative understanding regarding the generation of harmonics in the field of the plasma antenna, a bi-spectral analysis is performed to study the nonlinear interactions in the current fluctuations. Some specific features of the plasma antenna are investigated in our study, which may enhance the application prospect of the plasma antenna with respect to the conventional metallic antenna.
基金supported by Bhabha Atomic Research Centre, Department of Atomic Energy, Government of IndiaDepartment of Atomic Energy, Government of India for financial assistance under DAE Doctoral Fellowship Scheme-2018。
文摘Coaxial plasma guns are a type of plasma source that produces plasma which propagates radially and axially controlled by the shape of the ground electrode, which has attracted much interest in several applications. In this work, a 120° opening angle of CPG nozzle is used as a plasma gun configuration that operates at the energy of 150 J. The ionization of polyethylene insulator between the electrodes of the gun produces a cloud of hydrogen and carbon plasma.The triple Langmuir probe and Faraday cup are used to measure plasma density and plasma temperature. These methods are used to measure the on-axis and off-axis plasma divergence of the coaxial plasma gun. The peak values of ion densities measured at a distance of 25 mm on-axis from the plasma gun are(1.6±0.5)×10^(19)m^(-3)and(2.8±0.6)×10^(19)m^(-3)for hydrogen and carbon plasma respectively and the peak temperature is 3.02±0.5 eV. The mean propagation velocity of plasma is calculated using the transit times of plasma at different distances from the plasma gun and is found to be 4.54±0.25 cm/μs and 1.81±0.18 cm/μs for hydrogen and carbon plasma respectively. The Debye radius is obtained from the measured experimental data that satisfies the thin sheath approximation. The shot-to-shot stability of plasma parameters facilitates the use of plasma guns in laboratory experiments. These types of plasma sources can be used in many applications like plasma opening switches, plasma devices, and as plasma sources.
文摘A simple method for measuring RF plasma parameters by means of a DC-biased Langmuir probe is developed. The object of this paper is to ensure the reliability of this method by using the other methods with different principles. First, Langmuir probe current response on RF voltage superimposed to DC biased probe was examined in DC plasmas. Next, probe current response of DC biased probe in RF plasmas was studied and compared with the first experiment. The results were confirmed by using an emissive prove method, an ion acoustic wave method, and a square pulse response method. The method using a simple Langmuir probe is useful and convenient for measuring electron temperature , electron density , time-averaged space potential , and amplitude of space potential oscillation in RF plasmas with a frequency of the order of .
基金financially supported by National Natural Science Foundation of China(Nos.12075049 and 11935005)。
文摘The dual cylindrical inductively coupled plasma source,compared to the conventional structure of inductively coupled plasma source,can significantly improve the uniformity of plasma.It has an enhanced potential for application in processes,such as etching and ashing.A uniform plasma can be obtained by allowing the remote plasma from the upper chamber modulate the main plasma generated in the lower chamber.In this study,a fluid model was employed to investigate a dual cylindrical inductively coupled Ar/O_(2)discharge.The effects of external parameters on electron density,electron temperature,O atomic density,and plasma uniformity in the main chamber were studied,and the reasons were analyzed.The results of this study show that remote power can control the plasma uniformity and increase the plasma density in the main chamber.As the remote power increased,plasma uniformity improved initially and then deteriorated.The main power affected the plasma density at the edge of the main chamber and can modulate the plasma density in the main chamber.The gas pressure affected both the uniformity and density of the plasma.As the gas pressure increased,the plasma uniformity deteriorated,but the free radical density improved.
基金ACKNOWLEDGMENTS This study was supported by the National Science and Technology Support Program of the Ministry of Science and Technology （No. 2012BAI31B08）, the National Natural Science Foundation of China （No. 31171380）.
文摘In this experimental prospective study, we aimed to analyze the effect of transient scrotal hyperthermia on the male reproductive organs, from the perspective of sperm parameters, semen plasma biochemical markers, and oxidative stress, to evaluate whether different frequencies of heat exposure cause different degrees of damage to spermatogenesis. Two groups of volunteers （10 per group） received testicular warming in a 43~C water bath 10 times, for 30 min each time： group 1：10 consecutive days; group 2： once every 3 days. Sperm parameters, epididymis and accessory sex gland function, semen plasma oxidative stress and serum sex hormones were tested before treatment and in the 16-week recovery period after treatment. At last, we found an obvious reversible decrease in sperm concentration （P = 0.005 for Group 1 and P = 0.008 for Group 2 when the minimums were compared with baseline levels, the same below）, motility （P= 0.009 and 0.021, respectively）, the hypoosmotic swelling test score （P-- 0.007 and 0.008, respectively）, total acrosin activity （P = 0.018 and 0.009, respectively）, and an increase in the seminal plasma malondialdehyde concentration （P = 0.005 and 0.017, respectively）. The decrease of sperm concentration was greater for Group 2 than for Group 1 （P = 0.031）. We concluded that transient scrotal hyperthermia seriously, but reversibly, negatively affected the spermatogenesis, oxidative stress may be involved in this process. In addition, intermittent heat exposure more seriously suppresses the spermatogenesis compared to consecutive heat exposure. This may be indicative for clinical infertility etiology analysis and the design of contraceptive methods based on heat stress.
文摘Laser Induced Breakdown Spectroscopic(LIBS)technique was used to detect calcium and silicon in an unknown sample.In this method plasma was generated by Nd∶YAG laser of wavelength 1 064 nm with energy 400 mJ and pulse duration between 5~10ns.The method was applied for the qualitative as well as quantitative analysis.In the qualitative analysis,the electron number density(Ne)of plasma containing calcium and silicon is determined showing that Neof neutral particles is equivalent to 1016(cm-3)whereas for ionized particles it is 1017(cm-3).Plasma temperature is measured using Boltzmann plot method which must be greater than 10 000 k.Intensity ratio method is used for the quantitative analysis shows various elements in abundance with calcium and silicon in majority.
基金Project (2016YFB0300502) supported by the National Key Research and Development Program of ChinaProjects (51601129,51775386) supported by the National Natural Science Foundation of China+2 种基金Project (16PJ1410000) supported by Shanghai Pujiang Program,ChinaProject (16ZR1438700) supported by the Natural Science Foundation of Shanghai,ChinaProject (TPL1706) supported by Traction Power State Key Laboratory of Southwest Jiaotong University,China
文摘Ni-based composite coatings with a high content of tungsten carbides(Stelcar65composite coatings)were synthesized by plasma transferred arc(PTA)hardfacing.The welding parameters of Stelcar65composite coatings were optimized by orthogonal tests.The PTA welding parameters including welding current,powder feed rate and welding speed have significant influence on the tungsten carbide degradation.The values for the optimum welding current,powder feed rate and welding speed were determined to be100A,25g/min and40mm/min,respectively.The produced WC/Ni-based composite coatings were crack-and degradation-free.The microstructure of deposited layers,as well as the microstructure and microhardness of the optimal coating were further analyzed.
基金supported by Important National Science & Technology Specific Projects of China (No.2) (Nos.2009ZX02001,2011ZX02403)
文摘The geometry of an inductively coupled plasma （ICP） etcher is usually considered to be an important factor for determining both plasma and process uniformity over a large wafer. During the past few decades, these parameters were determined by the ＂trial and error＂ method, resulting in wastes of time and funds. In this paper, a new approach of regression orthogonal design with plasma simulation experiments is proposed to investigate the sensitivity of the structural parameters on the uniformity of plasma characteristics. The tool for simulating plasma is CFD-ACE＋, which is commercial multi-physical modeling software that has been proven to be accurate for plasma simulation. The simulated experimental results are analyzed to get a regression equation on three structural parameters. Through this equation, engineers can compute the uniformity of the electron number density rapidly without modeling by CFD-ACE＋. An optimization performed at the end produces good results.
文摘BACKGROUND Chronic obstructive pulmonary disease(COPD)is a chronic respiratory disease with worldwide occurrence and high disability and mortality rate.It occurs mostly in the elderly population with pulmonary heart disease,type II respiratory failure,and other serious complications.AIM To investigate the correlation of plasma brain natriuretic peptide(BNP)and platelet parameters with cardiac function and pulmonary hypertension in patients with COPD and pulmonary heart disease.METHODS From June 2016 to June 2019,52 patients with COPD-pulmonary heart disease(pulmonary heart disease group),30 patients with COPD(COPD group),and 30 healthy individuals(control group)in our hospital were enrolled in the study.The pulmonary heart disease group was further divided into subgroups according to cardiac function classification and pulmonary artery pressure.Plasma BNP and platelet parameters were estimated and compared among each group and subgroup.The correlation of plasma BNP and platelet parameters with cardiac function classification and pulmonary artery pressure was then analyzed.RESULTS In the pulmonary heart disease group,the COPD group,and the control group,the levels of plasma BNP,platelet distribution width(PDW),and mean platelet volume(MPV)showed a decreasing trend(P<0.05),while an increasing trend was found in platelet count(PLT)and plateletcrit(PCT)levels among the three groups(P<0.05).In the pulmonary hypertension mild,moderate,and severe subgroups,the levels of plasma BNP,PDW,and MPV showed an increasing trend(P<0.05),while a decreasing trend was observed in PLT levels(P<0.05);however,PCT levels showed no significant difference among the three subgroups(P>0.05).In the cardiac function grade I,II,III,and IV subgroups,the levels of plasma BNP,PDW,and MPV showed an increasing trend(P<0.05),while a decreasing trend was noted in PLT and PCT levels among the four subgroups(P<0.05).Correlation analysis showed that the levels of plasma BNP,PDW,and MPV in patients with pulmonary heart disease were positively correlated with their pulmonary artery pressure(P<0.05),while PLT was negatively correlated with their pulmonary artery pressure(P<0.05).Moreover,plasma BNP,PDW,and MPV levels were positively correlated with cardiac function grade(P<0.05)of these patients,while PLT and PCT levels were negatively correlated with their cardiac function grade(P<0.05).CONCLUSION Plasma BNP and PLT parameters are significantly correlated with the cardiac function and pulmonary hypertension in patients with COPD and pulmonary heart disease,indicating that these parameters have high clinical relevance in reflecting the health condition of these patients and for guiding their treatment.
基金National Natural Science Foundation of China (Grant No. 51905382)the Cooperation in Production and Education by Ministry of Education (Grant No. 201802252016)Weifang University Distinguished Professor Support Programme
文摘A certain amount of Ti was added to the plasma cladding Fe-Cr-C coating in the early stage in order to improve the quality and properties of the coating.Ti-Fe-Cr-C composite powder was prepared by precursor carbonization-composition process.In situ synthesized TiC-Fe-Cr coatings were fabricated on substrate of Q235 steel by plasma cladding process with the composite powder.Microstructures of the coatings with different process parameters,including cladding current,cladding speed,number of overlapping cladding layers,were analyzed by scanning electron microscope.The results show that the structure of the TiC-Fe-Cr coating is greatly affected by the cladding current,the cladding speed and the overlapping cladding process.In this test,when the cladding current of 300 A and the cladding process parameter of the cladding speed of 50 mm/min are clad with three layers,a well-formed and well-structured TiC-Fe-Cr coating can be obtained in this test.TiC-Fe-Cr coating has good wear resistance and good load characteristics under dry sliding wear test conditions.
文摘Air plasma spraying process was employed to fabricate various hydroxyapatite(HA)coatings on titanium substrates.The influence of processing parameters on the phase composition and the microstructure of the obtained coatings was investigated.The effect of heat treatment on as-sprayed coating in terms of the crystallinity and microstructure was also studied.The phase composition of coatings was analyzed by X-ray diffraction(XRD)and FTIR.The surface and cross-section morphologies and microstructure of coatings as well as the morphology of feedstock were evaluated using scanning electron microscope(SEM).The crystallization temperature of amorphous HA phase in as-sprayed coating was examined by using differential thermal analysis(DTA).The results suggest that phase composition and microstructure of as-sprayed HA coatings strongly depend on the spraying parameters,and heat treatment at 760℃for 2 h is one of effective means for increasing the crystallinity and improvement in microstructure of as-sprayed HA coatings.
基金This research was supported by Jilin Province Science Foundation （No. 20090552）.
文摘Al2O3p/Al composite coatings were prepared on the surface of AZ31 magnesium alloy by plasma spraying technology with mixed powders of Al and Al2O3. An orthogonal test containing six factors and five levels was carried out to acquire the optimum technical parameters. Mierostruetures and properties of the composite coatings were studied. The results show that the coatings consist of Al2O3 particulates distributed uniformly and Al matrix, and the interface between the particulate and matrix is continuous, compact and clean. With increasing the mass fraction of Al2O3 in the mixed powders, the volume fraction of Al2O3 in the coatings iacreases. The Al2O3p/Al composite coating with 14% Al2O3 volume fraction has more compact microstrueture and more satisfactory properties.
文摘Plasma source performance parameters, including plasma ejection density and velocity, greatly affect the operation of a short-conduction-time plasma opening switch （POS）. In this paper, the plasma source used in the POS of Qiangguang I generator is chosen as the study object. At first the POS working process is analyzed. The result shows that the opening performance of the POS can be improved by increasing the plasma ejection velocity and decreasing the plasma density. The influence of the cable plasma gun structure and number on the plasma ejection parameters is experimentally investigated with two charge collectors. Finally a semi-empirical model is proposed to describe the experimental phenomenon.
文摘Simulation of the core plasma parameters of HCSB-DEMO （helium-cooled solid breeder, HCSB）, by using a 1.5D plasma transport code, was carried out. The study includes investigations of operational scenarios, temperature and density profiles of both ions and electrons, fusion and radiated power, distribution of the safety factor, sensitivity analyses for some input parameters as well as a primary estimate of the divertor heating load. The results indicate that the following fusion reactor parameters can be properly set for HCSB-DEMO, namely major radius of 7.2 m, aspect ratio of 3.4, elongation of 1.85, triangularity of 0.45, plasma current of 14.8 MA, normalized beta of 4.4, toroidal field （TF） of 6.86 T, average electron density of 1.5× 10^20 m^-3, average electron temperature of 14.5 keV, fusion power of 2.55 GW, neutron wall loading of 2.3 MW.m^-2 and fusion multiplication factor of 35.
基金supported by National Key Technology Research and Development Program of the Ministry of Science and Technology of China(No.2013BAC06B02)Public Science and Technology Research Funds Projects of Ocean (No.201305027)+2 种基金National Natural Science Foundation of China(No.51877024)Liaoning Scientific Research Project of Department of Education of Liaoning Province(No.LZ2015007)High Level Talent Innovation Project of Dalian(No.2016RQ040)
文摘Matching optimization of resonant parameters among the high power inverters,low power transformers and plasma reactors have significant effects on the performance and output of the reactor array when applying the partitioned operation method.In this paper,the Matlab/Simulink electrical model was established based on the method of partitioned operation.The matching relation between resonant parameters is analyzed on the basis of experimental result.As a consequence,transformer leakage inductance and working frequency are the important parameters influencing the operational efficiency of system,leakage inductance of transformer should be adjusted based on the equivalent capacitance of plasma reactor to realize the matching optimization of resonant parameters.
基金supported by National Natural Science Foundation of China (No. 10875093)
文摘Ion parameters in electron cyclotron resonance （ECR） microwave plasma were measured by ion sensitive probe and were compared with the electron parameters obtained by double Langmuir probe. The effects of gas pressure and microwave power on the ion temperature and density were analyzed. The spatial distribution of the ion parameters was also investigated by the ion sensitive probes with a tunable radial depth installed on different probe windows along the chamber axis. Results showed that the ion density measured by the ion sensitive probe was in good agreement with the electron density measured by the double Langmuir probe. The influ- ence of gas pressure on the ion parameters was stronger than that of microwave power. With the increase in working pressure, the ion temperature decreased monotonously with a decreasing rate larger than that at higher pressure. The ion density first increased to a peak （42.3~ 101~ cm-3） at 1 Pa and then decreased. The ion temperature and density increased little with the increase in the microwave power from 400 W to 800 W, The plasma far away from the resonant point is found to be radially uniform.
基金support received from the State Key Laboratory of Animal Nutrition of China ( No .2004DA125184-0810)National Natural Science Foundation of China(No .31072040)+1 种基金Guangdong Cooperation Project be-tween Industry-Academia-Research of China ( No .2009B090300110)the Ministry of Science and Technology of the People’s Republic of China ( No .2006BAD12B05-10and No . Nyhyzx07-34)
文摘A total of 480 nursery pigs （Duroc x Landrace x Large White） were utilized in two experiments conducted to determine the effects of different ratios of standardized ileal digestible lysine （SID- Lys） to metabolizable energy （ME） ratio on the performance, nutrient digestibility, plasma urea nitrogen （PUN） ,and plasma free amino acids of 10 to 28 kg pigs. In Exp. 1, 192 pigs （ 10.58 kg） were assigned to one of four treatments. The treatments consisted of diets with a ME content of 3.2, 3.25, 3.3, or 3.35 Mcal/kg with a constant SID-Lys：ME ratio of 3.7 g/Mcal. The experiment lasted 28 days. Pigs which were fed the diets containing 3.3 and 3.35 Mcal/kg ME had lower feed intakes （ P 〈 0.05）than those fed 3.2 Mcal/kg. Feed efficiency was linearly improved with increasing dietary ME （ P 〈0.05）. Increasing the dietary ME level also increased （P 〈0.05 ） dry matter and energy digestibility. Therefore,3.3 Mcal/kg ME was selected for Exp. 2 in which 288 pigs （ 10.60 kg） were assigned to one of six treatments. Treatments consisted of SID-Lys： ME ratios of 3.1,3.3,3.5,3.7,3.9, or 4.1 g/Mcal with all diets providing 3.3 Mcal of ME/kg. Weight gain and feed efficiency were increased （P 〈0.05 ） as the SID-Lys：ME ratio in diet increased. Based on a straight broken-line model ,the estimated SID-Lys：ME ratio to maximize weight gain was 3.74.
