Article
Physics, Fluids & Plasmas
Zhaoyu Wang, Hong Li, Chao Zhong, Yanlin Hu, Yongjie Ding, Liqiu Wei, Daren Yu
Summary: The study shows that in a magnetically shielded Hall thruster, the channel wall can be effectively protected when the magnetic field strength matching the chamfered wall is less than 12% of the maximum strength, while high thruster performance is achieved when the magnetic field strength ratio is between 12% and 20%.
PLASMA SCIENCE & TECHNOLOGY
(2021)
Article
Physics, Applied
J. Pereles-Diaz, A. Dominguez-Vazquez, P. Fajardo, E. Ahedo, F. Faraji, M. Reza, T. Andreussi
Summary: Numerical simulations of a magnetically shielded Hall effect thruster with a centrally mounted cathode are described and discussed, focusing on the impact of magnetic configuration and central cathode on plasma behavior. Magnetic shielding significantly reduces energy fluxes, decreases heat loads, and minimizes wall erosion. Injection of neutrals at the central cathode facilitates electron drift and magnetic topology efficiently channels electron current away from lateral walls.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Physics, Fluids & Plasmas
M. Reza, F. Faraji, A. Knoll, A. Piragino, T. Andreussi, T. Misuri
Summary: High-power magnetically shielded Hall thrusters are being developed to meet the demands of future missions. However, there are still many unanswered questions about the behavior of plasma in these thrusters. In this article, we demonstrate the use of a reduced-order particle-in-cell simulation to study the physics in a high-power Hall thruster. The simulations show accurate results and provide insights into the plasma behavior and interactions with the walls.
PLASMA SOURCES SCIENCE & TECHNOLOGY
(2023)
Article
Physics, Fluids & Plasmas
J. Perales-Diaz, A. Dominguez-Vazquez, P. Fajardo, E. Ahedo
Summary: The operation of a 5 kW-class magnetically shielded Hall effect thruster with sinusoidal modulation of the discharge voltage is investigated through simulations. The dynamic response of the thruster for different modulation amplitudes and frequencies is presented and discussed. Voltage modulation enhances the amplitude of plasma oscillations and can effectively control their frequency when the modulation frequency is close to that of the natural breathing mode (BM) of the thruster.
PLASMA SOURCES SCIENCE & TECHNOLOGY
(2023)
Article
Physics, Applied
Wensheng Huang, Hani Kamhawi
Summary: In the development testing of a 12.5kW magnetically shielded Hall thruster, it was found that counterstreaming ions originating from the discharge channel and centrally mounted cathode were eroding the pole covers at high oblique angles of incidence. The high-energy tails in the energy distributions of ions may be a major contributor to erosion. Predictions of erosion behavior changes over time were in good agreement with wear testing measurements, indicating a need to study the traditionally considered low-energy ions and their role in pole erosion in magnetically shielded Hall thrusters.
JOURNAL OF APPLIED PHYSICS
(2021)
Article
Physics, Applied
Parker J. Roberts, Vernon H. Chaplin, Alejandro Lopez Ortega, Ioannis G. Mikellides
Summary: This study experimentally characterizes plasma oscillations below 100kHz in a high-power, magnetically shielded Hall-effect thruster. A laser-induced fluorescence diagnostic was used to measure the evolution of the axial ion velocity distribution. A method was developed to correct for artificial broadening of the distribution and accurately measure ion temperature. The research reveals time-dependent ion heating behavior and the exchange of energy between ions and oscillations.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Physics, Applied
Chao Zhong, Hong Li, Yanlin Hu, Zhaoyu Wang, Yongjie Ding, Liqiu Wei, Daren Yu
Summary: A magnetically shielded Hall thruster (MSHT) has a longer service life than a conventional unshielded Hall thruster (USHT) due to the shifting of the magnetic field. This study demonstrates that the radial position of the externally mounted hollow cathode has a different influence on the performance of the MSHT compared to the USHT. In addition, the study introduces the concept of electron cross-field transport loss, which was not previously considered.
APPLIED PHYSICS LETTERS
(2022)
Article
Physics, Applied
L. L. Su, B. A. Jorns
Summary: The performance gap between xenon and krypton propellants in a magnetically shielded Hall thruster is mainly influenced by mass utilization, and the efficiency difference widens with increasing discharge voltage.
JOURNAL OF APPLIED PHYSICS
(2021)
Article
Physics, Applied
Ioannis G. Mikellides, Alejandro Lopez Ortega
Summary: Analytical and numerical investigations have shown that the lower hybrid drift instability is active in a region of low-beta plasma outside the discharge channel of a magnetically shielded Hall thruster. This instability may lead to anomalous ion heating, altering the velocity field and enhancing the energy of the ions that strike nearby thruster surfaces.
JOURNAL OF APPLIED PHYSICS
(2021)
Article
Physics, Fluids & Plasmas
Nathan P. Brown, Muhannad M. Eladl, Adam M. Steinberg, Jason A. Deibel, Mitchell L. R. Walker
Summary: Through experiments, we demonstrated the capability of terahertz time-domain spectroscopy (THz-TDS) to measure the electron density and collision frequency of plasma, and studied the impact of different wall materials on these measurements. The results showed that the electron collision frequency is significantly affected by the wall material.
PLASMA SOURCES SCIENCE & TECHNOLOGY
(2021)
Article
Engineering, Aerospace
Antonio Piragino, Farbod Faraji, Maryam Reza, Eugenio Ferrato, Annalisa Piraino, Tommaso Andreussi
Summary: The study characterizes a 20 kW-class magnetically shielded Hall thruster in different configurations and operating at different background pressure levels. Results show a linear relationship between discharge current and thrust values with anode mass flow rate, with lower pressures leading to lower thrust and discharge current values. Comparison with a background flow model suggests performance changes due to background pressure could be caused by factors beyond external mass flow ingestion.
Article
Physics, Applied
Jacob Simmonds, Yevgeny Raitses
Summary: In wall-less Hall thrusters, ionization and ion acceleration occur outside the thruster, reducing interactions and promising longer lifespan. These non-conventional thrusters are simpler and easier to miniaturize for low power operation, but have lower performance due to larger plume divergence.
JOURNAL OF APPLIED PHYSICS
(2021)
Article
Engineering, Aerospace
Xingyu Liu, Hong Li, Zhongkai An, Yongjie Ding, Liqiu Wei, Daren Yu, Wei Mao
Summary: A new wall material was employed to improve the performance of Hall thrusters, and it was found that the length of the metallic wall significantly affects the thruster efficiency.
Article
Engineering, Aerospace
Chao Zhong, Hong Li, Yanlin Hu, Xu Zhang, Yongjie Ding, Liqiu Wei, Daren Yu
Summary: This study systematically investigated the influence of the position and inclination angle of an externally mounted hollow cathode in magnetically shielded Hall thrusters. The optimal cathode position and angle were determined, and a strong correlation was found between the plume image and thruster performance.
JOURNAL OF PROPULSION AND POWER
(2022)
Article
Multidisciplinary Sciences
P. J. Hobson, J. Vovrosh, B. Stray, M. Packer, J. Winch, N. Holmes, F. Hayati, K. McGovern, R. Bowtell, M. J. Brookes, K. Bongs, T. M. Fromhold, M. Holynski
Summary: Quantum sensors based on cold atoms require precise control of the internal magnetic field environment. Researchers have developed a solution using multiple coils overlaid on a 3D-printed former to generate uniform and linear gradient magnetic fields inside a cylindrical magnetic shield. This technology has the potential to reduce systematic shifts and noise in various cold atom systems.
SCIENTIFIC REPORTS
(2022)
Article
Materials Science, Multidisciplinary
Lei Wang, Yishen Xu, Yongjie Ding, Fan Xu, Limeng Bao, Yan Meng, Hong Li, Liqiu Wei, Daren Yu
Summary: In this study, the effects of the peak magnetic field location on the discharge characteristics of a 100-W Hall thruster with large-gradient magnetic field were investigated. It was found that the thruster performance significantly improves when the peak magnetic field is closer to the channel exit.
Article
Engineering, Aerospace
Xingyu Liu, Hong Li, Zhongkai An, Yongjie Ding, Liqiu Wei, Daren Yu, Wei Mao
Summary: A new wall material was employed to improve the performance of Hall thrusters, and it was found that the length of the metallic wall significantly affects the thruster efficiency.
Article
Physics, Applied
Tianyuan Ji, Liqiu Wei, Lu Wang, Ji Li, Yongguo Zhao, Tingwan Li, Tiance Liang, Hong Li, Ximing Zhu, Yongjie Ding
Summary: In this investigation, electrical detection was combined with enhanced ICCD spectroscopic detection to monitor the cathodic ionization process of the microcathodic arc thruster. The results showed that the microcathodic arc thruster exhibited a double peak of titanium ions in one cycle, which may be related to the combined effect of arc heat transfer and ion current impact on the cathode. The temporal relationship between arc power peak and arc current peak, and thus the ionization of the cathode, can be effectively influenced by changes in the input energy of the power processing unit.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
Zhou Liwei, Wei Liqiu, Yang Zhou, Suo Changyou, Li Jingjing, Zhou Desheng, Ding Yongjie, Li Hong, Tang Jingfeng
Summary: This paper constructs a double layer lumped parameter circuit model and uses virtual instrument technology to build a test device for studying the energy loss of surface dielectric barrier discharge (SDBD) thruster. Through analysis of time domain signals, it is found that the response current in the discharge plasma region is mainly capacitive current, and relaxation planned loss is the main form of energy loss.
Article
Materials Science, Multidisciplinary
Xinyong Yang, Liqiu Wei, Wenjia Jiang, Shangmin Wang, Yongfeng He, Hong Li, Yongjie Ding
Summary: In this study, a particle-in-cell model of ion optics was developed to simulate the changing trend of ion beam shape during ion optic start-up. The study aimed to investigate the effects of ion beam shape change on the accel grid and discuss the start-up strategy of ion optics. The results showed that the ions at the beam edge moved towards the centerline of the ion optics due to the electric field, resulting in the gradual shrinkage of the ion beam over time. It was also found that the accel grid could be protected from ion bombardment at the operating voltage, but it may still be bombarded during the low-voltage start-up process, affecting its lifespan. Therefore, ion dynamics must be considered during start-up.
Article
Physics, Applied
Tianyuan Ji, Liqiu Wei, Lu Wang, Yongguo Zhao, Tingwan Li, Tiance Liang, Hong Li, Ximing Zhu, Yongjie Ding
Summary: The relationship between the morphology of the cathode crater and plasma ionization between thrusters is studied by adjusting the input energy of the micro-cathode arc thruster (mu CAT). The morphology of the cathode crater of the mu CAT is monitored using scanning electron microscopy, and its relationship with the internal energy loss of the cathode crater is explored. The ionization between the electrodes of the mu CAT is monitored using a spectrum detector, based on the relationship and numerical simulation results.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2023)
Article
Physics, Applied
Lei Wang, Yi Li, Zekai Wang, Zijian Liu, Hong Li, Liqiu Wei, Yongjie Ding
Summary: In this study, the effects of magnetic field intensity near the inner magnetic pole on pole erosion of a 100 W permanent-magnet Hall thruster were investigated. The results showed that decreasing the magnetic field intensity near the inner magnetic pole significantly reduced the erosion rate, with a decrease of over 37.5% when the magnetic field intensity decreased by 20%. This reduction in erosion rate can be attributed to a decrease in the number of electrons reaching the magnetic pole and an increase in the potential of the pole, resulting in a decrease in ion sputtering.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
Xingyu Liu, Hong Li, Qiaohui Yu, Yongjie Ding, Liqiu Wei, Daren Yu, Shangmin Wang, Yanlin Hu
Summary: In a voltage-varying experiment of Hall thrusters, inward deflection of the excitation magnetic field was observed. The influence of Hall current magnitude and radial distribution on the total magnetic field was analyzed using magnetic field simulations. The probable reason for the inward deflection at high discharge voltages (>600 V) was obtained by combining simulation results and theoretical analysis. This study provides qualitative guidance for the design of excitation magnetic field in high-specific-impulse Hall thrusters.
Article
Engineering, Aerospace
Liwei Zhou, Zhou Yang, Liqiu Wei, Jingjing Li, Hong Li, Yongjie Ding
Summary: This study examines the characteristics of discharge and dynamics of surface dielectric barrier discharge ion-wind thrusters made of different materials on a Martian surface filled with carbon dioxide. The main causes of gas multipulse asymmetric discharge are found to be space-charge accumulation and electron backflow. The thrust and thrust-to-power ratio are mainly influenced by the space-charge and shielding effects of the discharge plasma region.
Article
Engineering, Aerospace
Demai Zeng, Hong Li, Jinwen Liu, Yanlin Hu, Yongjie Ding, Liqiu Wei, Daren Yu
Summary: By optimizing the aft-loaded magnetic field and internal cathode, expanding the envelope of the magnetic separatrix can improve plume focusing and enhance performance, highlighting the significance of the magnetic field for long-lifetime Hall thrusters.
Article
Physics, Fluids & Plasmas
Liwei Zhou, Liqiu Wei, Chong Teng, Desheng Zhou, Hong Li, Jingfeng Tang, Yongfeng He, Yongjie Ding
Summary: Based on surface dielectric barrier discharge (SDBD), this article proposes a composite dielectric structure for ionic wind actuator in near space. Experimental results show that the actuator with three-layer composite dielectric has lower dynamic permittivity and higher flow velocity compared to the single-layer quartz glass actuator. The actuator with three-layer composite dielectric also exhibits higher thrust, voltage, power and force-to-weight ratio.
IEEE TRANSACTIONS ON PLASMA SCIENCE
(2023)
Article
Physics, Applied
Tianyuan Ji, Liqiu Wei, Lu Wang, Ji Li, Yongguo Zhao, Ziying Ren, Tiance Liang, Haochen Ma, Hong Li, Ximing Zhu, Yongjie Ding
Summary: The energy supply mode of a micro-cathodic arc thruster (mu-CAT) was adjusted, and the cathode discharge characteristics of mu-CAT were studied under different energy supply modes. An electrical method was applied to measure the discharge characteristics of mu-CAT, and plasma parameters were measured using an enhanced intensified charge coupled device spectrum detector. The analysis of thruster plasma parameters, arc discharge characteristics, and energy supply mode revealed the effect of the energy supply mode on the discharge characteristics of mu-CAT.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Physics, Multidisciplinary
Haotian Fan, Shangmin Wang, Pei Li, Liqiu Wei, Hong Li, Ning Guo, Yongjie Ding
Summary: An optimization scheme of internally loaded magnetic field was proposed to improve the discharge performance of Hall thrusters with large height-radius ratio under high voltage. Simulation results show that the internally loaded magnetic field can enhance the ionization rate, reduce electron temperature, and improve the propellant utilization efficiency and current utilization efficiency.
Article
Materials Science, Multidisciplinary
Tianyuan Ji, Liqiu Wei, Zexin Liu, Haochen Ma, Wei Xi, Ji Li, Hong Li, Yongjie Ding
Summary: This research characterizes the relationships between different input PPU voltages of a micro cathode arc thruster and the plume shape, arc characteristics, thruster propulsion performance, and working fluid ionization. The results show that the change in energy input affects the plume contraction, arc duration, ionization rate, and propulsion efficiency. The degree of plume contraction primarily affects propulsion efficiency in high input voltage state, while arc ionization rate primarily affects thrust-to-power ratio in low input voltage state.
Article
Materials Science, Multidisciplinary
Ping Zhang, Xiujie Yue, Yeran Gao, Zhenyong Lin, Shunxiang Wang, Songting Zhang
Summary: This paper investigates the strengthening mechanism of highspeed cutting and solid particle-entrained waterjet peening (HSC-WJP) composite reinforcement on 7075-T6 aluminum alloy. The research results show that composite reinforcement can improve surface quality, reduce surface pits and roughness, and decrease the size of precipitation-free zone (PFZ) at grain boundaries.
Article
Materials Science, Multidisciplinary
Sangyoon Lee, Hwi Yoon, Sanghun Lee, Seung-min Chung, Hyungjun Kim
Summary: The wettability of metal oxides, particularly HfO2 thin films deposited via atomic layer deposition, and its correlation with surface free energy have been studied. It was found that surface oxygen species significantly affect the intrinsic hydrophilicity of HfO2 thin films, and the crystalline orientations also evolve with film thickness.
Article
Materials Science, Multidisciplinary
Changdong Yin, Yiwen Wu, Zhou Xu, Dongdong Ye, Jun Yao, Jianjun Chen, Qiang Liu, Xin Ge, Meiling Ding
Summary: This study proposed a new strategy to indirectly estimate the hydrogen diffusivity of metallic materials under tensile stress by combining the electrochemical hydrogen permeation test (EHPT), the hydrogen diffusion descriptive equation based on Fick's law, and hydrogen pre-charged tensile test. The results showed that the hydrogen permeation curve obtained was highly approximate to the theoretical trend. The hydrogen embrittlement (HE) susceptibility of the specimens increased with increasing stress.
Article
Materials Science, Multidisciplinary
Huan Luo, Wei-yi Wang, Xin Yu, Xian-jun Lei, Lang Liu, Guo-zheng Zha, Wen-long Jiang, Bin Yang, Bao-qiang Xu
Summary: Separating selenium and tellurium is a general challenge in material and non-ferrous metallurgical industries. This paper proposes a novel method that achieved efficient separation of selenium and tellurium using gas-liquid equilibrium phase diagram and valence regulation-vacuum gasification technique.
Article
Materials Science, Multidisciplinary
Fan Zhang, Rong Xin Wang, Aiqin Tian, Fangzhi Li, Jianping Liu, Hui Yang
Summary: Deposition of Pd/Pt/Au three-layer films on p-GaN under high and ultra-high vacuum conditions was studied to investigate the electrical contact properties. Linear I-V curves were observed in samples deposited under ultra-high vacuum conditions, while nonlinear I-V characteristics were obtained in samples deposited under high vacuum conditions. The study also found that the samples deposited under high vacuum conditions had higher amounts of oxygen and Pd oxide. The oxide layer had an additional influence on the electrical characteristics of the Pd/Pt/Au/p-GaN contact.
Article
Materials Science, Multidisciplinary
Hongli Liu, Chengzhe Liu, Ying Sui, Zhongxian Liu, Tiangang Zhang, Zhiqiang Zhang, Shuang Sun, Jianwei Jia
Summary: This study utilized polysiloxane and hafnium carbide to produce Si-N-C-O-Hf hybridized ceramic fibers, and obtained ceramic fibers with hemispherical particles on the surface through electrostatic spinning and pyrolysis. The ceramic fibers exhibited excellent thermal stability, oxidation resistance, and high temperature insulation.
Article
Materials Science, Multidisciplinary
M. Abaker, Nazar Elamin Ahmed, A. Saad, H. F. Khalil, E. M. M. Ibrahim, A. M. Adam
Summary: This paper systematically studied the internal structure and thermoelectric properties of In1-xGaxSb alloys prepared by melting synthesis at 1123 K. The results showed that doping with Ga in the In sites led to a significant increase in the Seebeck coefficient and power factor, while reducing the thermal conductivity. The maximum dimensionless figure of merit was observed at 403 K.
Article
Materials Science, Multidisciplinary
Fucheng Yu, Jinlong Ren, Jielin Zhang, Haiyang Chen, Xin Tian, Chenchen Feng, Cuixia Li, Jianbin Zhang, Xianxi Tang, Xiaogang Hou
Summary: An environmentally friendly ZnO@BiVO4 composite photocatalyst was prepared using in-situ self-assembly and solvothermal methods, demonstrating good photocatalytic performance. The mass ratio of BiVO4 and NCZ was found to influence the photocatalytic performance of the composite.
Article
Materials Science, Multidisciplinary
Yaoming Shao, Pingping Zheng, Tianhao Dong, Lianghuan Wei, Haifei Wu, Jianxiao Si
Summary: In this paper, Mg3Bi2 films were prepared on glass substrate using magnetron sputtering, and the phase composition and thermoelectric properties of the films were investigated with different atomic ratios. The films displayed a metastable cubic phase and high conductivity when the atomic ratio exceeded stoichiometry.
Article
Materials Science, Multidisciplinary
I. V. Uimanov, D. L. Shmelev, S. A. Barengolts
Summary: A two-dimensional axisymmetric model has been developed to study the prebreakdown processes in a cathode microprotrusion under an external electric field. The simulation results show that electrohydrodynamic instability leads to the formation of a nanometer-sized conical protrusion on the microprotrusion tip, significantly accelerating the heating process.
Article
Materials Science, Multidisciplinary
Weilun Zhang, Di Yang, Feng Gong, Yongjun Chen, Tian Chen, Zhiwen Xie, Sirui Yang
Summary: A novel Pt doping method was designed to improve the thermal stability of CrWN coating. The doping of Pt atoms effectively blocks the coherent growth of the grains and creates a significant mixing effect, resulting in a smooth surface with uniform element distribution.
Article
Materials Science, Multidisciplinary
Xiaoye Wang, Xiaoguang Yang, Wenna Du, Tao Yang
Summary: In this study, the effects of multiple growth parameters on self-catalyzed growth of InAs/GaSb axial heterostructured nanowires on Si substrate by MOCVD were investigated. It was found that the growth temperature and switching time have significant influences on the nanowire growth.
Article
Materials Science, Multidisciplinary
Weizhong Cui, Yan Zhao, Can Cui, Xing Liu, Beili Pang, Jianguang Feng, Hongzhou Dong, Liyan Yu, Lifeng Dong
Summary: This study introduces Co2+ cations into Cs2AgBiBr6 film to improve its quality, grain size, and conductivity, resulting in enhanced solar cell efficiency.
Article
Materials Science, Multidisciplinary
Jian Wang, Ke Yang, Xianming Cheng, Yalin Lu, Ganghui Wu, Yang Zhang, Yun Kan
Summary: The corrosion behavior and microstructural evolution of Sc microalloyed Al-3.2Cu-1.5Li alloys were investigated in detail. The microstructural results showed higher levels of dislocations density in the Sc microalloyed sample, which resulted in significantly refined grains and T1 precipitates. Microalloying with Sc changed the corrosion mode of the alloy and localized corrosion was found to occur preferentially at the subgrain within unrecrystallized grains with high grain stored energy.
Article
Materials Science, Multidisciplinary
Weifeng Liu, Na Liu, Kaiqiang Song, Meiqin Zeng, Zhongchen Lu
Summary: Monoclinic WO3 prepared through plasma milling exhibits higher photocatalytic activity due to its higher surface area, increased oxygen vacancies, and defects.