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Abnormal transition of the electron energy distribution with excitation of the second harmonic in low-pressure radio-frequency capacitively coupled plasmas

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Plasma Science and technology 2024年第8期26卷 58-63页

作者：余乐怡陆文琪张丽娜 key laboratory of materials modification by Laser Ionand Electron Beams(Ministry of Education)School of PhysicsDalian University of TechnologyDalian 116024People’s Republic of China

The self-excited second harmonic in radio-frequency capacitively coupled plasma was significantly enhanced by adjusting the external variable *** a lower pressure of 3 Pa,the excitation of the second harmonic caused an abnormal transition of the electron energy probability function,resulting in abrupt changes in the electron density and *** changes in the electron energy probability function as well as the electron density and temperature were not observed at the higher pressure of 16 Pa under similar harmonic *** phenomena are related to the influence of the second harmonic on stochastic heating,which is determined by both amplitude and the relative phase of the *** results suggest that the self-excited high-order harmonics must be considered in practical applications of lowpressure radio-frequency capacitively coupled plasmas.

关键词： radio-frequency capacitively coupled plasma harmonics the electron energy probability function

Defect-modulated synthesis and optoelectronic properties in chemical vapor deposited CsPbBr_(3) microplates

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Nano Research 2024年第5期17卷 4610-4615页

作者： Yanan Bao Hengshan Wang Meiqi An Huayi Tang Jing Li Jianliang Li Conghui Tan Yingmin Luo Jiao Xu Yiming Yang School of Microelectronics Dalian University of TechnologyDalian 116024China key laboratory of materials modification by Laser Ionand Electron Beams(Ministry of Education)School of PhysicsDalian University of TechnologyDalian 116024China

The remarkable optoelectronic features of halide perovskite promote their potential applications in semiconductor devices beyond solar cells,which require high-quality single crystals with controlled defect ***,we investigated the synthesis mechanism of chemical vapor deposited single-crystalline all-inorganic perovskite microplates(MPs),and reported a defect-modulated photocurrent which is closely related to the growth sequence of the *** MP synthesis initiates from island-like nano-disks,and subsequently transits to a layer-by-layer fashion,resulting in a defect-rich area at the center of the *** elevated temperatures,these central defects may be thermally activated and become highly mobile,leading to photoluminescence quenching and degression of local and overall optoelectronic attributes,as evidenced by the spatial resolved optical and electrical scanning probe ***,this work shines light on the formation,proliferation and dynamics of defects in perovskites,and offers guidance for preparation of high-quality perovskites micro-crystals for functional semiconductor devices with high temperature stability.

关键词： halide perovskites nanomaterials optoelectronics scanning photocurrent microscope chemical vapor deposition

Power transfer efficiency in an air-breathing radio frequency ion thruster

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Chinese Physics B 2024年第7期33卷 430-438页

作者：黄高煌李宏高飞王友年 key laboratory of materials modification by Laser Ionand Electron Beams(Ministry of Education)School of PhysicsDalian University of TechnologyDalian 116024China College of Physical Science and technology Dalian UniversityDalian 116622China

Due to a series of challenges such as low-orbit maintenance of satellites, the air-breathing electric propulsion has got widespread attention. Commonly, the radio frequency ion thruster is favored by low-orbit missions due to its high specific impulse and efficiency. In this paper, the power transfer efficiency of the radio frequency ion thruster with different gas compositions is studied experimentally, which is obtained by measuring the radio frequency power and current of the antenna coil with and without discharge operation. The results show that increasing the turns of antenna coils can effectively improve the radio frequency power transfer efficiency, which is due to the improvement of Q factor. In pure N_2 discharge,with the increase of radio frequency power, the radio frequency power transfer efficiency first rises rapidly and then exhibits a less steep increasing trend. The radio frequency power transfer efficiency increases with the increase of gas pressure at relatively high power, while declines rapidly at relatively low power. In N_(2)/O_(2) discharge, increasing the N_(2) content at high power can improve the radio frequency power transfer efficiency, but the opposite was observed at low power. In order to give a better understanding of these trends, an analytic solution in limit cases is utilized, and a Langmuir probe was employed to measure the electron density. It is found that the evolution of radio frequency power transfer efficiency can be well explained by the variation of plasma resistance, which is related to the electron density and the effective electron collision frequency.

关键词： radio frequency ion thruster inductively coupled plasma power transfer efficiency analytic solution

Effects of diamagnetic drift on nonlinear interaction between multi-helicity neoclassical tearing modes

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Chinese Physics B 2024年第6期33卷 452-458页

作者：王海源姜帅刘桐魏来栾其斌王正汹 key laboratory of materials modification by Laser Ionand Electron Beams of the Ministry of EducationSchool of PhysicsDalian University of TechnologyDalian 116024China Faculty of Electronic Information and Electrical Engineering Dalian University of TechnologyDalian 116024China

A numerical study of the diamagnetic drift effect on the nonlinear interaction between multi-helicity neoclassical tearing modes(NTMs) is carried out using a set of four-field equations including two-fluid *** results show that,in contrast to the single-fluid case,5/3 NTM cannot be completely suppressed by 3/2 NTM with diamagnetic drift *** modes exhibit oscillation and coexist in the saturated *** better understand the effect of the diamagnetic drift flow on multiple-helicity NTMs,the influence of typical relevant parameters is *** is found that the average saturated magnetic island width increases with increasing bootstrap current fraction f_(b) but decreases with the ion skin depth δ.In addition,as the ratio of parallel to perpendicular transport coefficients χ_(‖)/χ_(⊥) increases,the average saturated magnetic island widths of the 3/2 and 5/3 NTMs *** underlying mechanisms behind these observations are discussed in detail.

关键词： tokamak two-fluid neoclassical tearing modes multi-helicity

A multi-functional MgF_(2)/polydopamine/hyaluronan-astaxanthin coating on the biodegradable ZE21B alloy with better corrosion resistance and biocompatibility for cardiovascular application

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Journal of Magnesium and Alloys 2024年第3期12卷 1102-1116页

作者： Yachen Hou Xueqi Zhang Jingan Li Liguo Wang Shaokang Guan School of materials Science and Engineering and Henan key laboratory of Advanced Magnesium Alloy and key laboratory of materials Processing and Mold technology(ministry of education) Zhengzhou UniversityZhengzhou 450001China

The cardiovascular diseases(CVD)continue to be the major threat to global public health over the years,while one of the effective methods to treat CVD is stent *** magnesium(Mg)alloys have great potential applications in cardiovascular stents benefit from their excellent biodegradability and ***,excessive degradation rate and the delayed surface endothelialization still limit their further *** this study,we modified a Mg-Zn-Y-Nd alloy(ZE21B)by preparing MgF_(2) as the corrosion resistance layer,the dopamine polymer film(PDA)as the bonding layer,and hyaluronic acid(HA)loaded astaxanthin(ASTA)as an important layer to directing the cardiovascular cells *** electrochemical test results showed that the MgF_(2)/PDA/HA-ASTA coating improved the corrosion resistance of *** cytocompatibility experiments also demonstrated that this novel composite coating also selectively promoted endothelial cells proliferation,inhibited hyperproliferation of smooth muscle cells and adhesion of *** with the HAloaded rapamycin(RAPA)coating,our MgF_(2)/PDA/HA-ASTA coating showed better blood compatibility and cytocompatibility,indicating stronger multi-functions for the ZE21B alloy on cardiovascular application.

关键词： Biodegradable ZE21B alloy Reendothelialization Surface modification Hyaluronic acid Astaxanthin.

A Radiative-Cooling Hierarchical Aligned Porous Poly(vinylidene fluoride)Film by Freeze-Thaw-Promoted Nonsolvent-Induced Phase Separation

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Chinese Journal of Polymer Science 2024年第7期42卷 976-983,I0009页

作者： Yiting Zhang Jiahui Sun Yufeng Wang Yunchen Wu Chun Huang Chao Zhang Tianxi Liu key laboratory of Synthetic and Biological Colloids ministry of education School of Chemical and Material EngineeringJiangnan UniversityWuxi214122China State key laboratory for modification of Chemical Fibers and Polymer materials College of Materials Science and EngineeringDonghua UniversityShanghai201620China

Passive daytime radiative cooling(PDRC)is an innovative and sustainable cooling technology that holds immense potential for addressing the energy *** the numerous reports on radiative coolers,the design of a straightforward,efficient,and readily producible system remains a ***,we present the development of a hierarchical aligned porous poly(vinylidene fluoride)(HAP-PVDF)film through a freeze-thaw-promoted nonsolvent-induced phase separation *** film features oriented microporous arrays in conjunction with random nanopores,enabling efficient radiative cooling performance under direct sunlight *** incorporation of both micro-and nano-pores in the HAP-PVDF film results in a remarkable solar reflectance of 97%and a sufficiently high infrared thermal emissivity of 96%,facilitating sub-environmental cooling at 18.3℃ on sunny days and 13.1℃ on cloudy ***,the HAP-PVDF film also exhibits exceptional flexibility and *** calculations further confirm a radiative cooling power of 94.8 W·m^(-2)under a solar intensity of 1000W·m^(-2),demonstrating a performance comparable to the majority of reported radiative coolers.

关键词： Daytime radiative cooling Hierarchical porosity PVDF porous film Thermal insulation Nonsolvent-induced phase separation

Hot Compression Behavior and Tensile Property of a Novel Ni-Co-Based Superalloy Prepared by Electron beam Smelting Layered Solidification technology

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Acta Metallurgica Sinica(English Letters) 2024年第2期37卷 283-292页

作者： Yong-Chao Gai Rui Zhang Chuan-Yong Cui Zi-Jian Zhou Yi Tan Yi-Zhou Zhou Xiao-Feng Sun key laboratory of materials modification by Laser Ionand Electron Beams(Ministry of Education)School of Materials Science and EngineeringDalian University of TechnologyDalian116024China Shi-Changxu Innovation Center for Advanced materials Institute of Metal ResearchChinese Academy of SciencesShenyang110016China

The hot compression behavior and tensile strength after compression of a new Ni-Co-based superalloy produced using electron beam smelting layered(EBSL)solidification technology were *** compression tests were performed at temperatures of 1120℃and 1150℃,with strain rates of 1 s^(-1) and 0.01 s^(-1),reaching a true strain of *** strength was evaluated at room *** results revealed that this EBSL technology accelerates dynamic recrystallization(DRX),without compromising the strength of alloy.A significant correlation between the volume fraction of DRX and the strain rate was observed,with higher fractions at lower strain rates,leading to higher tensile ***,at the same strain rate,the specimens compressed at 1120℃exhibited higher tensile strength due to undissolvedγ′*** solution and aging heat treatment,the alloy maintained high tensile *** results suggested that the EBSL Ni-Co-based superalloy offers excellent prospects for practical applications.

关键词： Ni-Co-based superalloy Hot deformation Electron beam smelting Tensile strength

Effect of a negative DC bias on a capacitively coupled Ar plasma operated at different radiofrequency voltages and gas pressures

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Plasma Science and technology 2024年第5期26卷 62-71页

作者：相垚君王晓坤刘永新王友年 key laboratory of materials modification by Laser Ionand Electron Beams(Ministry of Education)School of PhysicsDalian University of TechnologyDalian 116024People’s Republic of China Chair of Applied Electrodynamics and Plasma technology Ruhr University BochumBochum 44801Germany

The effect of a negative DC bias,|V_(dc)|,on the electrical parameters and discharge mode is investigated experimentally in a radiofrequency(RF)capacitively coupled Ar plasma operated at different RF voltage amplitudes and gas *** electron density is measured using a hairpin probe and the spatio-temporal distribution of the electron-impact excitation rate is determined by phase-resolved optical emission *** electrical parameters are obtained based on the waveforms of the electrode voltage and plasma current measured by a voltage probe and a current *** was found that at a low|V_(dc)|,***α-mode,the electron density and RF current decline with increasing|V_(dc)|;meanwhile,the plasma impedance becomes more capacitive due to a widened ***,RF power deposition is ***|V_(dc)|exceeds a certain value,the plasma changes toα–γhybrid mode(or the discharge becomes dominated by theγ-mode),manifesting a drastically growing electron density and a moderately increasing RF ***,the plasma impedance becomes more resistive,so RF power deposition is enhanced with|V_(dc)|.We also found that the electrical parameters show similar dependence on|V_(dc)|at different RF voltages,andα–γmode transition occurs at a lower|V_(dc)|at a higher RF *** increasing the pressure,plasma impedance becomes more resistive,so RF power deposition and electron density are *** particular,theα–γmode transition tends to occur at a lower|V_(dc)|with increase in pressure.

关键词： RF capacitively coupled plasma DC-overlapped RF discharge power deposition discharge mode transition

In situ luminescence measurements of GaN/Al_(2)O_(3) film under different energy proton irradiations

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Chinese Physics B 2024年第5期33卷 704-710页

作者：蒋文丽欧阳潇仇猛淋英敏菊陈琳庞盼张春雷张耀锋廖斌 key laboratory of beam technology of ministry of education College of Nuclear Science and TechnologyBeijing Normal UniversityBeijing 100875China Institute of Radiation technology Beijing Academy of Science and TechnologyBeijing 100875China

Ion beam-induced luminescence(IBIL) experiments were performed to investigate the in situ luminescence of GaN/Al_(2)O_(3) at varying ion energies,which allowed for the measurement of defects at different depths within the *** energies of H^(+)were set to 500 keV,640 keV and 2 MeV,the Bragg peaks of which correspond to the GaN film,GaN/Al_(2)O_(3) heterojunction and Al_(2)O_(3) substrate,respectively.A photoluminescence measurement at 250 K was also performed for comparison,during which only near band edge(NBE) and yellow band luminescence in the GaN film were *** evolution of the luminescence of the NBE and yellow band in the GaN film was discussed,and both exhibited a decrease with the fluence of H^(+).Additionally,the luminescence of F centers,induced by oxygen vacancies,and Cr^(3+),resulting from the ^(2)E →^(4)A_(2) radiative transition in Al_(2)O_(3),were measured using 2 MeV H^(+).The luminescence intensity of F centers increases gradually with the fluence of H^(+).The luminescence evolution of Cr^(3+)is consistent with a yellow band center,attributed to its weak intensity,and it is situated within the emission band of the yellow band in the GaN *** results show that IBIL measurement can effectively detect the luminescence behavior of multilayer films by adjusting the ion *** measurement can be excited by various techniques,but IBIL can satisfy in situ luminescence measurement,and multilayer structural materials of tens of micrometers can be measured through IBIL by adjusting the energy of the inducing *** evolution of defects at different layers with ion fluence can be obtained.

关键词： ion beam-induced luminescence(IBIL) GaN/Al_(2)O_(3) ion beam