Low-power Hall thruster(LHT) generally has poor discharge efficiency characteristics due to the large surface-to-volume ratio.Aiming to further refine and improve the performance of 300 W class LHT in terms of thrust ...Low-power Hall thruster(LHT) generally has poor discharge efficiency characteristics due to the large surface-to-volume ratio.Aiming to further refine and improve the performance of 300 W class LHT in terms of thrust and efficiency,and to obtain the most optimal operating point,the experimental study of the discharge characteristics for three different anode positions was conducted under the operation of various discharge voltages(100-400 V) and anode mass flow rates(0.65 mg·s-1and 0.95 mg·s-1).The experimental results indicated that the thruster has the most excellent performance in terms of thrust and efficiency etc at a channel length of 27 mm for identical operating conditions.In addition,particle in cell simulations,employed to reveal the underlying physical mechanisms,show that the ionization and acceleration zone is pushed downwards towards the channel exit as the anode moves towards the exit.At the identical operating point,when the channel length is reduced from 32 to 27 mm,the ionization and acceleration zone moves towards the exit,and the parameters such as thrust and efficiency increase due to the high ionization rate,ion number density,and axial electric field.When the channel length is further moved to 24 mm,the parameters in terms of thrust(F) and efficiency(ηa) are reduced as a result of the decreasing ionization efficiency(ηm) and the larger plume divergence angle(α).In this paper,the results indicated that an optimum anode position(ΔL=27 mm) exists for the optimum performance.展开更多
A 200 W cylindrical Hall thruster with a cusp-type magnetic field was proposed, manifesting convergent plume and high specific impulse. In this paper, a series of ring-shaped anodes are designed and the influence of a...A 200 W cylindrical Hall thruster with a cusp-type magnetic field was proposed, manifesting convergent plume and high specific impulse. In this paper, a series of ring-shaped anodes are designed and the influence of anode axial position on the performance of CHT with a cusp-type magnetic field is studied. The experimental results indicate that the thruster keeps stable operation at the condition of 140–270 W discharge power. When the anode moves axially towards the upstream cusp field, the thrust enhances from 6.5 mN to 7.6 mN and specific impulse enhances from 1658 s to 1939 s significantly. These improvements of thruster performance should be attributed to the enhancement of current utilization, propellant utilization and acceleration efficiency. According to the analyses on the discharge characteristics, it is revealed that as the anode moves upstream, the electron transport path could be extended, the magnetic field in this extended path could impede electron cross-field transport and facilitate the ionization intensity, yielding to the enhancement of current utilization and propellant utilization efficiency.Moreover, along with this enhancement of upstream ionization at the given anode flow rate, the main ionization region is thought to move upstream and then separate more apparently from the acceleration region, which has been demonstrated by the narrowing of ion energy distribution function shape. This change in acceleration region could decrease the ion energy loss and enhance acceleration efficiency. This work is beneficial for optimizing the electrode structure of thruster and recognize the ionization and acceleration process under the cusp magnetic field.展开更多
University hall is an important carrier of information exchange and sharing in higher education campuses,and the correct architectural design positioning can improve the value of university halls.There are many differ...University hall is an important carrier of information exchange and sharing in higher education campuses,and the correct architectural design positioning can improve the value of university halls.There are many different features in the design and use of university halls and urban theaters.This paper investigates the feasibility study report and indexes of university hall projects,analyzes the indexes,construction scale and functional positioning of university halls in the pre-design period,summarizes some design suggestions,and believes that the use efficiency of university halls should be improved through intensive and compound construction to meet the needs of the rapid development of Chinas Universitys and universities.展开更多
磁敏位置传感系统广泛应用于汽车、高端装备和先进制造等领域中。文中设计了一种基于霍尔效应的位置传感系统,可以实现被测物旋转角度的检测。该系统通过由线性霍尔芯片和磁铁组成的传感模块获取旋转角度信息,经信号调理电路处理后由12 ...磁敏位置传感系统广泛应用于汽车、高端装备和先进制造等领域中。文中设计了一种基于霍尔效应的位置传感系统,可以实现被测物旋转角度的检测。该系统通过由线性霍尔芯片和磁铁组成的传感模块获取旋转角度信息,经信号调理电路处理后由12 bit ADC采样转换为数字信号,FPGA读取数据并采用拟合、标准化等算法校准,再利用Cordic算法计算得到被测物旋转角度,最后通过串口屏将测量结果显示。测试结果表明该位置传感系统精度较高,测得的旋转角度误差小于2°。展开更多
文章针对无刷直流电机(Brushless Direct Current Motor,BLDCM)控制系统霍尔位置传感器故障中常见的单霍尔故障,分别分析了霍尔对电源短路故障和霍尔开路故障2种故障模式,并提出了采用霍尔状态编码值对单霍尔故障进行诊断和定位的方法...文章针对无刷直流电机(Brushless Direct Current Motor,BLDCM)控制系统霍尔位置传感器故障中常见的单霍尔故障,分别分析了霍尔对电源短路故障和霍尔开路故障2种故障模式,并提出了采用霍尔状态编码值对单霍尔故障进行诊断和定位的方法。同时,提出一种实用的霍尔故障修复方法。经过仿真验证和分析证实,文章所提方法能够有效实现单霍尔故障的定位和修复。展开更多
基金National Natural Science Foundation of China (No.12005087)Science and Technology Program of Gansu Province (Nos.2006ZCTF0054, HTKJ2019KL510003,and 20JR10RA478)。
文摘Low-power Hall thruster(LHT) generally has poor discharge efficiency characteristics due to the large surface-to-volume ratio.Aiming to further refine and improve the performance of 300 W class LHT in terms of thrust and efficiency,and to obtain the most optimal operating point,the experimental study of the discharge characteristics for three different anode positions was conducted under the operation of various discharge voltages(100-400 V) and anode mass flow rates(0.65 mg·s-1and 0.95 mg·s-1).The experimental results indicated that the thruster has the most excellent performance in terms of thrust and efficiency etc at a channel length of 27 mm for identical operating conditions.In addition,particle in cell simulations,employed to reveal the underlying physical mechanisms,show that the ionization and acceleration zone is pushed downwards towards the channel exit as the anode moves towards the exit.At the identical operating point,when the channel length is reduced from 32 to 27 mm,the ionization and acceleration zone moves towards the exit,and the parameters such as thrust and efficiency increase due to the high ionization rate,ion number density,and axial electric field.When the channel length is further moved to 24 mm,the parameters in terms of thrust(F) and efficiency(ηa) are reduced as a result of the decreasing ionization efficiency(ηm) and the larger plume divergence angle(α).In this paper,the results indicated that an optimum anode position(ΔL=27 mm) exists for the optimum performance.
基金support from the Defense Industrial Technology Development Program (No. JCKY2019601D112)。
文摘A 200 W cylindrical Hall thruster with a cusp-type magnetic field was proposed, manifesting convergent plume and high specific impulse. In this paper, a series of ring-shaped anodes are designed and the influence of anode axial position on the performance of CHT with a cusp-type magnetic field is studied. The experimental results indicate that the thruster keeps stable operation at the condition of 140–270 W discharge power. When the anode moves axially towards the upstream cusp field, the thrust enhances from 6.5 mN to 7.6 mN and specific impulse enhances from 1658 s to 1939 s significantly. These improvements of thruster performance should be attributed to the enhancement of current utilization, propellant utilization and acceleration efficiency. According to the analyses on the discharge characteristics, it is revealed that as the anode moves upstream, the electron transport path could be extended, the magnetic field in this extended path could impede electron cross-field transport and facilitate the ionization intensity, yielding to the enhancement of current utilization and propellant utilization efficiency.Moreover, along with this enhancement of upstream ionization at the given anode flow rate, the main ionization region is thought to move upstream and then separate more apparently from the acceleration region, which has been demonstrated by the narrowing of ion energy distribution function shape. This change in acceleration region could decrease the ion energy loss and enhance acceleration efficiency. This work is beneficial for optimizing the electrode structure of thruster and recognize the ionization and acceleration process under the cusp magnetic field.
文摘University hall is an important carrier of information exchange and sharing in higher education campuses,and the correct architectural design positioning can improve the value of university halls.There are many different features in the design and use of university halls and urban theaters.This paper investigates the feasibility study report and indexes of university hall projects,analyzes the indexes,construction scale and functional positioning of university halls in the pre-design period,summarizes some design suggestions,and believes that the use efficiency of university halls should be improved through intensive and compound construction to meet the needs of the rapid development of Chinas Universitys and universities.
文摘磁敏位置传感系统广泛应用于汽车、高端装备和先进制造等领域中。文中设计了一种基于霍尔效应的位置传感系统,可以实现被测物旋转角度的检测。该系统通过由线性霍尔芯片和磁铁组成的传感模块获取旋转角度信息,经信号调理电路处理后由12 bit ADC采样转换为数字信号,FPGA读取数据并采用拟合、标准化等算法校准,再利用Cordic算法计算得到被测物旋转角度,最后通过串口屏将测量结果显示。测试结果表明该位置传感系统精度较高,测得的旋转角度误差小于2°。
文摘文章针对无刷直流电机(Brushless Direct Current Motor,BLDCM)控制系统霍尔位置传感器故障中常见的单霍尔故障,分别分析了霍尔对电源短路故障和霍尔开路故障2种故障模式,并提出了采用霍尔状态编码值对单霍尔故障进行诊断和定位的方法。同时,提出一种实用的霍尔故障修复方法。经过仿真验证和分析证实,文章所提方法能够有效实现单霍尔故障的定位和修复。
