Temperature fluctuations challenge ectothermic species,particularly tropical fish dependent on external temperatures for physiological regulation.However,the molecular mechanisms through which low-temperature stress i...Temperature fluctuations challenge ectothermic species,particularly tropical fish dependent on external temperatures for physiological regulation.However,the molecular mechanisms through which low-temperature stress impacts immune responses in these species,especially in relation to chromatin accessibility and epigenetic regulation,remain poorly understood.In this study,we investigate chromatin and transcriptional changes in the head kidney and thymus tissues of Nile tilapia(Oreochromis niloticus),a tropical fish of significant economic importance,under cold stress.By analyzing cis-regulatory elements in open chromatin regions and their associated transcription factors(TFs),we construct a comprehensive transcriptional regulatory network(TRN)governing immune responses,including DNA damage-induced apoptosis.Our analysis identifies 119 TFs within the TRN,with Stat1 emerging as a central hub exhibiting distinct binding dynamics under cold stress,as revealed by footprint analysis.Overexpression of Stat1 in immune cells leads to apoptosis and increases the expression of apoptosis-related genes,many of which contain Stat1-binding sites in their regulatory regions,emphasizing its critical role in immune cell survival during cold stress.These results provide insights into the transcriptional and epigenetic regulation of immune responses to cold stress in tilapia and highlight Stat1 as a promising target for enhancing cold tolerance in tropical fish species.展开更多
Hepatitis B virus(HBV)infection is a global health concern.The current sequen-tial endpoints for the treatment of HBV infection include viral suppression,hepatitis B e antigen(HBeAg)seroconversion,functional cure,and ...Hepatitis B virus(HBV)infection is a global health concern.The current sequen-tial endpoints for the treatment of HBV infection include viral suppression,hepatitis B e antigen(HBeAg)seroconversion,functional cure,and covalently closed circular DNA(cccDNA)clearance.Serum hepatitis B core-related antigen(HBcrAg)is an emerging HBV marker comprising three components:HBeAg,hepatitis B core antigen,and p22cr.It responds well to the transcriptional activity of cccDNA in the patient's liver and is a promising alternative marker for serolo-gical testing.There is a strong correlation,and a decrease in its level corresponds to sustained viral suppression.In patients with chronic hepatitis B(CHB),serum HBcrAg levels are good predictors of HBeAg seroconversion(both spontaneous and after antiviral therapy),particularly in HBeAg-positive patients.Both low baseline HBcrAg levels and decreasing levels early in antiviral therapy favored HBsAg seroconversion,which may serve as a good surrogate option for treatment endpoints.In this review,we summarize the role of serum HBcrAg in the treat-ment of CHB.Therefore,long-term continuous monitoring of serum HBcrAg levels contributes to the clinical management of patients with CHB and optimizes the choice of treatment regimen,making it a promising marker for monitoring HBV cure.展开更多
BACKGROUND Inferior mesenteric arteriovenous fistula(IMAVF)is an extremely rare condition characterized by abnormal communication between the inferior mesenteric artery and vein.IMAVF often mimics ischemic bowel disea...BACKGROUND Inferior mesenteric arteriovenous fistula(IMAVF)is an extremely rare condition characterized by abnormal communication between the inferior mesenteric artery and vein.IMAVF often mimics ischemic bowel disease and ulcerative colitis(UC),leading to diagnostic challenges and treatment failures.CASE SUMMARY Three consecutive cases presented with non-specific symptoms including perianal pain and bloody diarrhea were reported.Initial diagnosis included acute severe UC and ischemic colitis.Pathology suggested ischemic changes,and with further contrast-enhanced computed tomography together with digital subtraction angiography which confirmed the diagnosis of IMAVF.All three cases were treated by vascular embolization,and symptoms improved rapidly following treatment.CONCLUSION We presented the largest single center IMAVF series with detailed clinical characteristics,facilitating early diagnosis for similar cases in the future.展开更多
Dispersing metals from nanoparticles to clusters is often achieved using ligand protection methods,which exhibit unique properties such as suppressing structure-sensitive side reactions.However,this method is limited ...Dispersing metals from nanoparticles to clusters is often achieved using ligand protection methods,which exhibit unique properties such as suppressing structure-sensitive side reactions.However,this method is limited by the use of different metal precursor salts corresponding to different ligands.An alternative approach,the ion exchange(IE)method,can overcome this limitation to some extent.Nevertheless,there is still an urgent need to address the stabilization of metals(especially precious metals)by using IE method.Here,we reported a Pt cluster catalyst prepared mainly by anchoring Pt atoms via O located near the framework Zn in zincosilicate zeolites and riveted by zeolite surface rings after reduction(reduced Pt/Zn-3-IE).The catalyst can achieve an initial propane conversion of 26%in a pure propane atmosphere at 550℃and shows little deactivation even after 7.5 d of operation.Moreover,the alteration of catalyst by the introduction of framework Zn was also highlighted and interpreted.展开更多
The effect of(CaO+SiO_(2))mass ratio on high-Ti vanadium titanomagnetite sintering was systematically studied at the fixed basicity(CaO/SiO_(2))of 2.0.The results show that sinter matrix strength is improved with(CaO+...The effect of(CaO+SiO_(2))mass ratio on high-Ti vanadium titanomagnetite sintering was systematically studied at the fixed basicity(CaO/SiO_(2))of 2.0.The results show that sinter matrix strength is improved with(CaO+SiO_(2))mass ratio while the total iron content is reduced.Thermodynamic analysis indicates that the increase in(CaO+SiO_(2))mass ratio from 15.0 to 22.5 wt.%contributes to the formation of liquid phase,especially silico-ferrite of calcium and aluminum(SFCA).In addition,the formation of perovskite is inhibited and liquid phase fluidity is improved.The porosity of sinter matrix is reduced by 34.5%and SFCA amount is increased by 47.2%when(CaO+SiO_(2))mass ratio is increased from 15.0 to 18.0 wt.%.With the further increase in(CaO+SiO_(2))mass ratio,the structure of sinter matrix is too dense and the improved extent of SFCA amount is increasingly low.The appropriate(CaO+SiO_(2))mass ratio should be 18.0 wt.%overall.Under this condition,sinter matrix strength is greatly improved by over 13.5%compared with the base case and the total iron content can be maintained at about 49 wt.%.展开更多
Aiming at the global design issue of transpiration cooling thermal protection system,a self-driven circulation loop is proposed as the internal coolant flow passage for the transpiration cooling structure to achieve a...Aiming at the global design issue of transpiration cooling thermal protection system,a self-driven circulation loop is proposed as the internal coolant flow passage for the transpiration cooling structure to achieve adaptive cooling.To enhance the universality of this internal cooling pipe design and facilitate its application,numerical studies are conducted on this systemwith four commonly used cooling mediums as coolant.Firstly,the accuracy of the numerical method is verified through an established experimental platform.Then,transient numerical simulations are performed on the flow states of different cooling mediums in the new self-circulation system.Based on the numerical result,the flow,phase change,and heat transfer characteristics of different cooling mediums are analyzed.Differences in fluid velocity and latent heat of phase change result in significant variation in heat exchange capacity among different coolingmediums,with the maximumdifference reaching up to 3 times.Besides,faster circulation speed leads to greater heat transfer capacity,with a maximum of 7600 W/m^(2).Consequently,the operating mechanism and cooling laws of the natural circulation system is further investigated,providing a reference for the practical application of this system.展开更多
Traditional Si-based photoconductive detectors face problems such as low response in the ultraviolet(UV)and infrared regions,high dark current,and low light absorption efficiency,which seriously limit their applicatio...Traditional Si-based photoconductive detectors face problems such as low response in the ultraviolet(UV)and infrared regions,high dark current,and low light absorption efficiency,which seriously limit their applications in the field of high-performance wide-spectrum detection.In this study,a self-powered broadband photodetector based on a Si/TiO_(2)heterojunction is proposed.The detector has a pyramidal structure.By constructing a pyramidal microstructure on the surface of silicon,the light capture and absorption efficiency is significantly improved,representing a breakthrough in response performance in the visible and near-infrared(NIR)bands.In order to further enhance the photoelectric response in the UV band,a TiO_(2)layer was coated on the surface of the silicon pyramid through a simple spin-coating method and annealing process.The introduction of TiO_(2)effectively broadened the spectral response range of the photoelectric detector and further improved the light absorption of the device.Meanwhile,due to the built-in electric field formed by the n-TiO_(2)/p-Si heterojunction,the dark current was effectively reduced,and the responsivity was improved.Experiments showed that the device exhibits high responsivity,high detectivity,and relatively low dark current in the range of 365-1305 nm.Under light at 780 nm,the device’s on-off ratio reached 2.7×10^(3);its specific detectivity,D^(*),was 3.9×10^(11)Jones;and its responsivity reached 0.174 A/W.In addition,this detector does not require the assistance of expensive equipment.Its preparation process is simple and inexpensive,and there is no need for an external power supply,which gives it broad application potential in wearable devices,environmental monitoring,communications,biosensing,and other fields.This study provides a brand-new strategy for the design of new wide-spectrum detectors.展开更多
Room-temperature sodium-sulfur batteries are promising grid-scale energy storage systems owing to their high energy density and low cost.However,their application is limited by the dissolution of long-chain sodium pol...Room-temperature sodium-sulfur batteries are promising grid-scale energy storage systems owing to their high energy density and low cost.However,their application is limited by the dissolution of long-chain sodium polysulfides and slow redox kinetics.To address these issues,a cobalt single-atom catalyst with N/O dual coordination was derived from a metal-organic framework precursor(denoted as Co-N_(2)O_(2)/MOFc)for sulfur storage.Theoretical analysis demonstrates that,compared with the Co-N4 structure,the introduction of oxygen atoms can further tune the d-electron density of Co atoms via the coordinative effect,which enhances d-p hybridization after Na_(2)Sx adsorption on Co-N_(2)O_(2)/MOFc.This leads to higher adsorption energy for Na_(2)Sx,lower Gibbs free energy for the rate-limiting process and a decreased Na_(2)S decomposition energy barrier,thereby promoting the polysulfide conversion reaction kinetics.When used as a sulfur host,the Co-N_(2)O_(2)/MOFc/S cathode exhibits excellent performance with a capacity of 590 mAh·g^(-2)(983 mAh·g^(-2)normalized by the sulfur mass)after 100 cycles at 0.1 A·g^(-2)and an excellent rate capability of 350 mAh·g^(-2)at 10 A·g^(-2).展开更多
The Amazon basin plays a crucial role in biodiversity and carbon storage,but its local rainfall is anticipated to decrease under globalwarming.Carbon dioxide removal(CDR)is being considered as a method to mitigate the...The Amazon basin plays a crucial role in biodiversity and carbon storage,but its local rainfall is anticipated to decrease under globalwarming.Carbon dioxide removal(CDR)is being considered as a method to mitigate the impact of global warming.However,the specific effects of CDR on Amazon rainfall have not been well understood.Here,an idealized CDR experiment reveals that the reduced rainfall over the Amazon basin does not recover.Significantly weaker rainfall is found during the ramp-down period compared to the ramp-up period at the same CO_(2)concentration.This response is associated with the enhanced El Niño-like warming in the tropical Pacific Ocean during the CDR period.This warming pattern has dual effects:weakening the zonal circulation and causing anomalous descent directly over the Amazon basin,while also triggering a stationary Rossby wave train that propagated downstream and generated anomalous ascent over the Sargasso Sea.This anomalous ascent induces anomalous descent and weakens moisture transport over the Amazon basin by the local meridional circulation.Consequently,precipitation is reduced over the Amazon basin in response to the weakened zonal and meridional circulation.Our findings indicate that even if the atmospheric CO_(2)concentration is lowered,the Amazon basin will remain susceptible to drought.Effective local climate adaptation strategies are urgently needed to address the vulnerability of this critical ecosystem.展开更多
A new magnetic field configuration is proposed by introducing a cusped field to the helicon plasma thruster(HPT),and the effects of the cusped field on the discharge characteristics of the HPT are investigated.The exp...A new magnetic field configuration is proposed by introducing a cusped field to the helicon plasma thruster(HPT),and the effects of the cusped field on the discharge characteristics of the HPT are investigated.The experimental results show that the thruster can still achieve a stable W mode discharge with the additional cusped field,while the discharge conditions have been changed so that a higher RF power is required to achieve the W mode under the same experimental conditions.However,the ion density in the plume region is increased by at least one order of magnitude and the ion flux density is increased by a factor of 4 to 5.The ionization enhancement is attributed to the change in magnetic field configuration,which improves the energy coupling efficiency and the ability to confine charged particles(particularly electrons).This magnetic confinement could employ more electrons to ionize the working medium atoms,and the ionization rate is enhanced.The increase in ion density leads to a reduction in the energy available for ion acceleration,resulting in a slight decrease in ion energy.展开更多
基金supported by the National Natural Science Foundation of China(32130109 and 32373113)the National Natural Science Foundation of Shanghai(23ZR1426800)SciTech Funding by CSPFTZ Lingang Special Area Marine Biomedical Innovation Platform.
文摘Temperature fluctuations challenge ectothermic species,particularly tropical fish dependent on external temperatures for physiological regulation.However,the molecular mechanisms through which low-temperature stress impacts immune responses in these species,especially in relation to chromatin accessibility and epigenetic regulation,remain poorly understood.In this study,we investigate chromatin and transcriptional changes in the head kidney and thymus tissues of Nile tilapia(Oreochromis niloticus),a tropical fish of significant economic importance,under cold stress.By analyzing cis-regulatory elements in open chromatin regions and their associated transcription factors(TFs),we construct a comprehensive transcriptional regulatory network(TRN)governing immune responses,including DNA damage-induced apoptosis.Our analysis identifies 119 TFs within the TRN,with Stat1 emerging as a central hub exhibiting distinct binding dynamics under cold stress,as revealed by footprint analysis.Overexpression of Stat1 in immune cells leads to apoptosis and increases the expression of apoptosis-related genes,many of which contain Stat1-binding sites in their regulatory regions,emphasizing its critical role in immune cell survival during cold stress.These results provide insights into the transcriptional and epigenetic regulation of immune responses to cold stress in tilapia and highlight Stat1 as a promising target for enhancing cold tolerance in tropical fish species.
基金Supported by The Chongqing Talents Project,No.cstc2021ycjh-bgzxm0150The First Batch of Key Disciplines on Public Health in Chongqing,The Health Commission of Chongqing,No.2022(72)+1 种基金The Remarkable Innovation-Clinical Research Project,The Second Affiliated Hospital of Chongqing Medical UniversityThe Scientific and Technological Research Program of Chongqing Municipal Education Commission,the Second Affiliated Hospital of Chongqing Medical University,No.KJZD-K202300404.
文摘Hepatitis B virus(HBV)infection is a global health concern.The current sequen-tial endpoints for the treatment of HBV infection include viral suppression,hepatitis B e antigen(HBeAg)seroconversion,functional cure,and covalently closed circular DNA(cccDNA)clearance.Serum hepatitis B core-related antigen(HBcrAg)is an emerging HBV marker comprising three components:HBeAg,hepatitis B core antigen,and p22cr.It responds well to the transcriptional activity of cccDNA in the patient's liver and is a promising alternative marker for serolo-gical testing.There is a strong correlation,and a decrease in its level corresponds to sustained viral suppression.In patients with chronic hepatitis B(CHB),serum HBcrAg levels are good predictors of HBeAg seroconversion(both spontaneous and after antiviral therapy),particularly in HBeAg-positive patients.Both low baseline HBcrAg levels and decreasing levels early in antiviral therapy favored HBsAg seroconversion,which may serve as a good surrogate option for treatment endpoints.In this review,we summarize the role of serum HBcrAg in the treat-ment of CHB.Therefore,long-term continuous monitoring of serum HBcrAg levels contributes to the clinical management of patients with CHB and optimizes the choice of treatment regimen,making it a promising marker for monitoring HBV cure.
文摘BACKGROUND Inferior mesenteric arteriovenous fistula(IMAVF)is an extremely rare condition characterized by abnormal communication between the inferior mesenteric artery and vein.IMAVF often mimics ischemic bowel disease and ulcerative colitis(UC),leading to diagnostic challenges and treatment failures.CASE SUMMARY Three consecutive cases presented with non-specific symptoms including perianal pain and bloody diarrhea were reported.Initial diagnosis included acute severe UC and ischemic colitis.Pathology suggested ischemic changes,and with further contrast-enhanced computed tomography together with digital subtraction angiography which confirmed the diagnosis of IMAVF.All three cases were treated by vascular embolization,and symptoms improved rapidly following treatment.CONCLUSION We presented the largest single center IMAVF series with detailed clinical characteristics,facilitating early diagnosis for similar cases in the future.
文摘Dispersing metals from nanoparticles to clusters is often achieved using ligand protection methods,which exhibit unique properties such as suppressing structure-sensitive side reactions.However,this method is limited by the use of different metal precursor salts corresponding to different ligands.An alternative approach,the ion exchange(IE)method,can overcome this limitation to some extent.Nevertheless,there is still an urgent need to address the stabilization of metals(especially precious metals)by using IE method.Here,we reported a Pt cluster catalyst prepared mainly by anchoring Pt atoms via O located near the framework Zn in zincosilicate zeolites and riveted by zeolite surface rings after reduction(reduced Pt/Zn-3-IE).The catalyst can achieve an initial propane conversion of 26%in a pure propane atmosphere at 550℃and shows little deactivation even after 7.5 d of operation.Moreover,the alteration of catalyst by the introduction of framework Zn was also highlighted and interpreted.
基金supported by National Natural Science Foundation of China(No.52304344)Postdoctoral Science Foundation of China(No.2024T171095)Cooperation Project of Pangang Group.Author information。
文摘The effect of(CaO+SiO_(2))mass ratio on high-Ti vanadium titanomagnetite sintering was systematically studied at the fixed basicity(CaO/SiO_(2))of 2.0.The results show that sinter matrix strength is improved with(CaO+SiO_(2))mass ratio while the total iron content is reduced.Thermodynamic analysis indicates that the increase in(CaO+SiO_(2))mass ratio from 15.0 to 22.5 wt.%contributes to the formation of liquid phase,especially silico-ferrite of calcium and aluminum(SFCA).In addition,the formation of perovskite is inhibited and liquid phase fluidity is improved.The porosity of sinter matrix is reduced by 34.5%and SFCA amount is increased by 47.2%when(CaO+SiO_(2))mass ratio is increased from 15.0 to 18.0 wt.%.With the further increase in(CaO+SiO_(2))mass ratio,the structure of sinter matrix is too dense and the improved extent of SFCA amount is increasingly low.The appropriate(CaO+SiO_(2))mass ratio should be 18.0 wt.%overall.Under this condition,sinter matrix strength is greatly improved by over 13.5%compared with the base case and the total iron content can be maintained at about 49 wt.%.
基金funded by Fei He,National Natural Science Foundation of China(contract no.52376154)Anhui Provincial Natural Science Foundation(contract no.2308085J21).
文摘Aiming at the global design issue of transpiration cooling thermal protection system,a self-driven circulation loop is proposed as the internal coolant flow passage for the transpiration cooling structure to achieve adaptive cooling.To enhance the universality of this internal cooling pipe design and facilitate its application,numerical studies are conducted on this systemwith four commonly used cooling mediums as coolant.Firstly,the accuracy of the numerical method is verified through an established experimental platform.Then,transient numerical simulations are performed on the flow states of different cooling mediums in the new self-circulation system.Based on the numerical result,the flow,phase change,and heat transfer characteristics of different cooling mediums are analyzed.Differences in fluid velocity and latent heat of phase change result in significant variation in heat exchange capacity among different coolingmediums,with the maximumdifference reaching up to 3 times.Besides,faster circulation speed leads to greater heat transfer capacity,with a maximum of 7600 W/m^(2).Consequently,the operating mechanism and cooling laws of the natural circulation system is further investigated,providing a reference for the practical application of this system.
基金supported by the National Natural Science Foundation of China(Grant Nos.51902255 and 51803168)the Natural Science Foundation of Shaanxi Province(Grant No.2023-JC-YB-015)+1 种基金the Shaanxi Province Key Research and Development Projects(Grant No.2022GY-356)the Shaanxi Universities’Youth Innovation Team(Grant No.23JP174).
文摘Traditional Si-based photoconductive detectors face problems such as low response in the ultraviolet(UV)and infrared regions,high dark current,and low light absorption efficiency,which seriously limit their applications in the field of high-performance wide-spectrum detection.In this study,a self-powered broadband photodetector based on a Si/TiO_(2)heterojunction is proposed.The detector has a pyramidal structure.By constructing a pyramidal microstructure on the surface of silicon,the light capture and absorption efficiency is significantly improved,representing a breakthrough in response performance in the visible and near-infrared(NIR)bands.In order to further enhance the photoelectric response in the UV band,a TiO_(2)layer was coated on the surface of the silicon pyramid through a simple spin-coating method and annealing process.The introduction of TiO_(2)effectively broadened the spectral response range of the photoelectric detector and further improved the light absorption of the device.Meanwhile,due to the built-in electric field formed by the n-TiO_(2)/p-Si heterojunction,the dark current was effectively reduced,and the responsivity was improved.Experiments showed that the device exhibits high responsivity,high detectivity,and relatively low dark current in the range of 365-1305 nm.Under light at 780 nm,the device’s on-off ratio reached 2.7×10^(3);its specific detectivity,D^(*),was 3.9×10^(11)Jones;and its responsivity reached 0.174 A/W.In addition,this detector does not require the assistance of expensive equipment.Its preparation process is simple and inexpensive,and there is no need for an external power supply,which gives it broad application potential in wearable devices,environmental monitoring,communications,biosensing,and other fields.This study provides a brand-new strategy for the design of new wide-spectrum detectors.
基金supported by the National Natural Science Foundation of China(Nos.22369026 and 22362031)the Basic Research Project General Program of Yunnan Province(No.202401CF070025)the Sichuan Science and Technology Program(No.24NSFSC3150).
文摘Room-temperature sodium-sulfur batteries are promising grid-scale energy storage systems owing to their high energy density and low cost.However,their application is limited by the dissolution of long-chain sodium polysulfides and slow redox kinetics.To address these issues,a cobalt single-atom catalyst with N/O dual coordination was derived from a metal-organic framework precursor(denoted as Co-N_(2)O_(2)/MOFc)for sulfur storage.Theoretical analysis demonstrates that,compared with the Co-N4 structure,the introduction of oxygen atoms can further tune the d-electron density of Co atoms via the coordinative effect,which enhances d-p hybridization after Na_(2)Sx adsorption on Co-N_(2)O_(2)/MOFc.This leads to higher adsorption energy for Na_(2)Sx,lower Gibbs free energy for the rate-limiting process and a decreased Na_(2)S decomposition energy barrier,thereby promoting the polysulfide conversion reaction kinetics.When used as a sulfur host,the Co-N_(2)O_(2)/MOFc/S cathode exhibits excellent performance with a capacity of 590 mAh·g^(-2)(983 mAh·g^(-2)normalized by the sulfur mass)after 100 cycles at 0.1 A·g^(-2)and an excellent rate capability of 350 mAh·g^(-2)at 10 A·g^(-2).
基金supported by the National Natural Science Foundation of China(Nos.42141019,42175055,and 42261144687)the second Tibetan Plateau Scientific Expedition and Research program(No.2019QZKK0102)。
文摘The Amazon basin plays a crucial role in biodiversity and carbon storage,but its local rainfall is anticipated to decrease under globalwarming.Carbon dioxide removal(CDR)is being considered as a method to mitigate the impact of global warming.However,the specific effects of CDR on Amazon rainfall have not been well understood.Here,an idealized CDR experiment reveals that the reduced rainfall over the Amazon basin does not recover.Significantly weaker rainfall is found during the ramp-down period compared to the ramp-up period at the same CO_(2)concentration.This response is associated with the enhanced El Niño-like warming in the tropical Pacific Ocean during the CDR period.This warming pattern has dual effects:weakening the zonal circulation and causing anomalous descent directly over the Amazon basin,while also triggering a stationary Rossby wave train that propagated downstream and generated anomalous ascent over the Sargasso Sea.This anomalous ascent induces anomalous descent and weakens moisture transport over the Amazon basin by the local meridional circulation.Consequently,precipitation is reduced over the Amazon basin in response to the weakened zonal and meridional circulation.Our findings indicate that even if the atmospheric CO_(2)concentration is lowered,the Amazon basin will remain susceptible to drought.Effective local climate adaptation strategies are urgently needed to address the vulnerability of this critical ecosystem.
基金sponsored by the National Key Research and Development Program of China(Nos.2020YFC2201100 and 2021YFE0116000)National Natural Science Foundation of China(Nos.12175032,12102082,12275044,52372373 and 12211530449)+4 种基金the Fundamental Research Funds for the Central Universities(Nos.DUT22GF305 and DUT22QN232)S&T Program of Hebei Province(Nos.YCYZ202201 and 216Z1901G)S&T Innovation Program of Hebei Province(Nos.SJMYF2022X18 and SJMYF2022X 06)Beijing Nova Program(No.20240484718)Langfang Science and Technology Program(No.2022011039).
文摘A new magnetic field configuration is proposed by introducing a cusped field to the helicon plasma thruster(HPT),and the effects of the cusped field on the discharge characteristics of the HPT are investigated.The experimental results show that the thruster can still achieve a stable W mode discharge with the additional cusped field,while the discharge conditions have been changed so that a higher RF power is required to achieve the W mode under the same experimental conditions.However,the ion density in the plume region is increased by at least one order of magnitude and the ion flux density is increased by a factor of 4 to 5.The ionization enhancement is attributed to the change in magnetic field configuration,which improves the energy coupling efficiency and the ability to confine charged particles(particularly electrons).This magnetic confinement could employ more electrons to ionize the working medium atoms,and the ionization rate is enhanced.The increase in ion density leads to a reduction in the energy available for ion acceleration,resulting in a slight decrease in ion energy.
