The current sheath velocity in 0.25 Torr gas pressure of Filippov type plasma focus is studied experimentally. By using two tridimensional magnetic probes on top of the anode surface, the current sheath velocity is me...The current sheath velocity in 0.25 Torr gas pressure of Filippov type plasma focus is studied experimentally. By using two tridimensional magnetic probes on top of the anode surface, the current sheath velocity is measured for argon, oxygen and nitrogen. Additionally, the effect of charging voltage on the current sheath velocity is studied in both axial and radial phases. We found that, the maximum current sheath velocities at both radial and axial phases are respectively 4.33 ± 0.28 （cm/μs） and 3.92 ± 0.75 （cm/μs） with argon as the working gas at 17 kV. Also, the minimum values of current sheath velocity are 1.48 ± 0.15 （cm/μs） at the radial phase and 1.14 ± 0.09 （cm/μs） at the axial phase with oxygen at 12 kV. The current sheath velocity at the radial phase is higher than that at the axial phase for all gases and voltages. In this study, variation of the full width half maximum （FWHM） of magnetic probe signals with voltage is investigated for different gases at radial and axial phases.展开更多
We report a simple-to-perform technique to investigate the distribution of the azimuthal magnetic field induction,Bθ,and the induced magnetic force acting on the plasma current sheath(PCS)in a plasma focus(PF)dischar...We report a simple-to-perform technique to investigate the distribution of the azimuthal magnetic field induction,Bθ,and the induced magnetic force acting on the plasma current sheath(PCS)in a plasma focus(PF)discharge.This in situ measurement technique can undoubtedly be beneficial when other fast-imaging techniques are not available.techniques are not available.Experimental work was conducted in the low-energy Mather-type EAEA-PF1 device operated in argon.The axial distribution(Bθ)z along the coaxial electrodes system was measured with a four magnetic-probe set technique at different radial distances(r=2.625×10^(−2) to 4.125×10^(−2) m)within the annular space between the coaxial electrodes during the 1st and 2nd half cycles of the discharge current waveform,where inner electrode of coaxial electrode system has a+ve polarity and−ve polarity,respectively.Axial,radial and total magnetic force distribution profiles were estimated from Bθdata.Investigation of PCS shape in terms of its inclination(curvature)angle,θ,along the axial rundown phase and the correlation between the magnetic forces per unit volume acting on the PCS,the inclination angleθof the PCS,and the formation of a powerful PF action during the 1st and 2nd half cycles is carried out.Dependence of inclination angle,θ,on total magnetic force per unit volume acting on PCS axial motion was studied,separately,during the 1st and 2nd half cycles.展开更多
Focused ion beam (FIB) machining can be used to fabricate gallium arsenide-based devices, which have a surface fnish of several nanometers, and the FIB machining speed and surface fnish can be greatly improved using x...Focused ion beam (FIB) machining can be used to fabricate gallium arsenide-based devices, which have a surface fnish of several nanometers, and the FIB machining speed and surface fnish can be greatly improved using xenon difuoride (XeF2) gas-assisted etching. Although the refresh time is one of the most important parameters in the gas-assisted etching process, its efect on the machining quality of the surface fnish has rarely been studied. Therefore, in this work, we investigated the efect of the refresh time on the etching process, including the dissociation process of XeF2, the refresh time dependency of the sputter in yield under diferent incident angles, and the surface fnish under diferent refresh times. The results revealed that a selective etching mechanism occurred at diferent refresh times. At an incidence angle of 0°, the sputtering yield increased with the refresh time and reached its maximum value at 500 ms;at an incidence angle of 30°, the sputtering yield reached its minimum value at a refresh time of 500 ms. For surface roughness, the incident angle played a more important role than the refresh time. The surface fnish was slightly better at an incidence angle of 30° than at 0°. In addition, both F and Xe elements were detected in the processed area: Xe elements were evenly distributed throughout the processing area, while F elements tended to accumulate in the whole processing area. The results suggest that the optimum surface can be obtained when a larger refresh time is employed.展开更多
介绍了一种利用超声驻波对颗粒进行二维聚焦的方案,其可用于流式细胞仪中微量(少于82μL)细胞样品的上样,无需鞘液即可实现颗粒在管道中央的逐个排列,并能以高至0.5 m L/min的速度依次通过检测区。该方案避免了颗粒在管道中的随机分布现...介绍了一种利用超声驻波对颗粒进行二维聚焦的方案,其可用于流式细胞仪中微量(少于82μL)细胞样品的上样,无需鞘液即可实现颗粒在管道中央的逐个排列,并能以高至0.5 m L/min的速度依次通过检测区。该方案避免了颗粒在管道中的随机分布现象,提高了流式细胞检测的准确性,分析后的样品还能被无稀释地回收再利用。从驻波形成、声阻抗匹配、颗粒在声场中的受力分析等理论出发,着重仿真分析了驻波场中颗粒在不同参数下的运动路径。在理论模型的基础上搭建了1.462 MHz频率驱动的方形毛细管实验平台,利用10和20μm直径的聚苯乙烯微球验证了超声聚焦颗粒的可行性,实验表明低流速、高声场强度时聚焦更紧密,大颗粒比小颗粒更易聚焦。该结论与仿真结果一致。展开更多
文摘The current sheath velocity in 0.25 Torr gas pressure of Filippov type plasma focus is studied experimentally. By using two tridimensional magnetic probes on top of the anode surface, the current sheath velocity is measured for argon, oxygen and nitrogen. Additionally, the effect of charging voltage on the current sheath velocity is studied in both axial and radial phases. We found that, the maximum current sheath velocities at both radial and axial phases are respectively 4.33 ± 0.28 （cm/μs） and 3.92 ± 0.75 （cm/μs） with argon as the working gas at 17 kV. Also, the minimum values of current sheath velocity are 1.48 ± 0.15 （cm/μs） at the radial phase and 1.14 ± 0.09 （cm/μs） at the axial phase with oxygen at 12 kV. The current sheath velocity at the radial phase is higher than that at the axial phase for all gases and voltages. In this study, variation of the full width half maximum （FWHM） of magnetic probe signals with voltage is investigated for different gases at radial and axial phases.
文摘We report a simple-to-perform technique to investigate the distribution of the azimuthal magnetic field induction,Bθ,and the induced magnetic force acting on the plasma current sheath(PCS)in a plasma focus(PF)discharge.This in situ measurement technique can undoubtedly be beneficial when other fast-imaging techniques are not available.techniques are not available.Experimental work was conducted in the low-energy Mather-type EAEA-PF1 device operated in argon.The axial distribution(Bθ)z along the coaxial electrodes system was measured with a four magnetic-probe set technique at different radial distances(r=2.625×10^(−2) to 4.125×10^(−2) m)within the annular space between the coaxial electrodes during the 1st and 2nd half cycles of the discharge current waveform,where inner electrode of coaxial electrode system has a+ve polarity and−ve polarity,respectively.Axial,radial and total magnetic force distribution profiles were estimated from Bθdata.Investigation of PCS shape in terms of its inclination(curvature)angle,θ,along the axial rundown phase and the correlation between the magnetic forces per unit volume acting on the PCS,the inclination angleθof the PCS,and the formation of a powerful PF action during the 1st and 2nd half cycles is carried out.Dependence of inclination angle,θ,on total magnetic force per unit volume acting on PCS axial motion was studied,separately,during the 1st and 2nd half cycles.
基金The authors gratefully acknowledge the startup funding support by the Dalian University of Technology(DUT)(Award No.82232022,82232043,and DUT22LAB404)。
文摘Focused ion beam (FIB) machining can be used to fabricate gallium arsenide-based devices, which have a surface fnish of several nanometers, and the FIB machining speed and surface fnish can be greatly improved using xenon difuoride (XeF2) gas-assisted etching. Although the refresh time is one of the most important parameters in the gas-assisted etching process, its efect on the machining quality of the surface fnish has rarely been studied. Therefore, in this work, we investigated the efect of the refresh time on the etching process, including the dissociation process of XeF2, the refresh time dependency of the sputter in yield under diferent incident angles, and the surface fnish under diferent refresh times. The results revealed that a selective etching mechanism occurred at diferent refresh times. At an incidence angle of 0°, the sputtering yield increased with the refresh time and reached its maximum value at 500 ms;at an incidence angle of 30°, the sputtering yield reached its minimum value at a refresh time of 500 ms. For surface roughness, the incident angle played a more important role than the refresh time. The surface fnish was slightly better at an incidence angle of 30° than at 0°. In addition, both F and Xe elements were detected in the processed area: Xe elements were evenly distributed throughout the processing area, while F elements tended to accumulate in the whole processing area. The results suggest that the optimum surface can be obtained when a larger refresh time is employed.
文摘介绍了一种利用超声驻波对颗粒进行二维聚焦的方案,其可用于流式细胞仪中微量(少于82μL)细胞样品的上样,无需鞘液即可实现颗粒在管道中央的逐个排列,并能以高至0.5 m L/min的速度依次通过检测区。该方案避免了颗粒在管道中的随机分布现象,提高了流式细胞检测的准确性,分析后的样品还能被无稀释地回收再利用。从驻波形成、声阻抗匹配、颗粒在声场中的受力分析等理论出发,着重仿真分析了驻波场中颗粒在不同参数下的运动路径。在理论模型的基础上搭建了1.462 MHz频率驱动的方形毛细管实验平台,利用10和20μm直径的聚苯乙烯微球验证了超声聚焦颗粒的可行性,实验表明低流速、高声场强度时聚焦更紧密,大颗粒比小颗粒更易聚焦。该结论与仿真结果一致。
