In this study,a pulsed,high voltage driven hollow-cathode electron beam sources through an optical trigger is designed with characteristics of simple structure,low cost,and easy triggering.To validate the new design,t...In this study,a pulsed,high voltage driven hollow-cathode electron beam sources through an optical trigger is designed with characteristics of simple structure,low cost,and easy triggering.To validate the new design,the characteristics of hollow-cathode discharge and electron beam characterization under pulsed high voltage drive are studied experimentally and discussed by discharge characteristics and analyses of waveform details,respectively.The validation experiments indicate that the pulsed high voltage supply significantly improves the frequency and stability of the discharge,which provides a new solution for the realization of a high-frequency,high-energy electron beam source.The peak current amplitude in the high-energy electron beam increases from 6.2 A to 79.6 A,which indicates the pulsed power mode significantly improves the electron beam performance.Besides,increasing the capacitance significantly affects the highcurrent,lower-energy electron beam more than the high-energy electron beam.展开更多
In order to investigate the process of optically triggered discharge formation,a model of ion space-charge formation based on classical plane electrodes and revised for a characteristic hollow-cathode discharge(HCD)co...In order to investigate the process of optically triggered discharge formation,a model of ion space-charge formation based on classical plane electrodes and revised for a characteristic hollow-cathode discharge(HCD)configuration is proposed in this paper.The primary modified factor in our model is the penetrating electric-field parameter,which influences the ionization of trigger electrons and is calculated via particle simulation.Optical-trigger experiments are carried out using different voltages and under different seed-electron conditions,provided by two different photocathodes,Cu and Mg.The ion-accumulation rates calculated by our model are compared to the discharge-formation time,which is deduced from optical-trigger experiments.The results demonstrate that the process of positive space-charge formation is dominant in the HCD formation process or trigger delay,which is highly dependent on the seeding-electron density and applied voltage,and can therefore be quantitatively described by our model.Additionally,electron-beam generation is investigated by optically triggered HCD experiments on Mg-and Cu-photocathode-based devices.The results show that a more efficient trigger device is capable of generating an electron beam with higher amplitude and density.展开更多
Low-temperature energy harvest,delivery,and utilization pose significant challenges for thermal management in extreme environments owing to heat loss during transport and difficulty in temperature control.Herein,we pr...Low-temperature energy harvest,delivery,and utilization pose significant challenges for thermal management in extreme environments owing to heat loss during transport and difficulty in temperature control.Herein,we propose a light-driven photo-energy delivery device with a series of photo-responsive alkoxy-grafted azobenzene-based phase-change materials(a-g-Azo PCMs).These a-g-Azo PCMs store and release crystallization and isomerization enthalpies,reaching a high energy density of 380.76 J/g even at a low temperature of-63.92℃.On this basis,we fabricate a novel three-branch light-driven microfluidic control device for distributed energy recycling that achieves light absorption,energy storage,controlled movement,and selective release cyclically over a wide range of temperatures.The a-g-Azo PCMs move remote-controllably in the microfluidic device at an average velocity of 0.11-0.53 cm/s owing to the asymmetric thermal expansion effect controlled by the temperature difference.During movement,the optically triggered heat release of a-g-Azo PCMs achieves a temperature difference of 6.6℃ even at a low temperature of-40℃.These results provide a new technology for energy harvest,delivery,and utilization in low-temperature environments via a remote manipulator.展开更多
基金supported by National Natural Science Foundation of China(No.12102099)the National Key R&D Program of China(No.2021YFC2202700)the Outstanding Academic Leader Project of Shanghai(Youth)(No.23XD1421700),respectively。
文摘In this study,a pulsed,high voltage driven hollow-cathode electron beam sources through an optical trigger is designed with characteristics of simple structure,low cost,and easy triggering.To validate the new design,the characteristics of hollow-cathode discharge and electron beam characterization under pulsed high voltage drive are studied experimentally and discussed by discharge characteristics and analyses of waveform details,respectively.The validation experiments indicate that the pulsed high voltage supply significantly improves the frequency and stability of the discharge,which provides a new solution for the realization of a high-frequency,high-energy electron beam source.The peak current amplitude in the high-energy electron beam increases from 6.2 A to 79.6 A,which indicates the pulsed power mode significantly improves the electron beam performance.Besides,increasing the capacitance significantly affects the highcurrent,lower-energy electron beam more than the high-energy electron beam.
文摘In order to investigate the process of optically triggered discharge formation,a model of ion space-charge formation based on classical plane electrodes and revised for a characteristic hollow-cathode discharge(HCD)configuration is proposed in this paper.The primary modified factor in our model is the penetrating electric-field parameter,which influences the ionization of trigger electrons and is calculated via particle simulation.Optical-trigger experiments are carried out using different voltages and under different seed-electron conditions,provided by two different photocathodes,Cu and Mg.The ion-accumulation rates calculated by our model are compared to the discharge-formation time,which is deduced from optical-trigger experiments.The results demonstrate that the process of positive space-charge formation is dominant in the HCD formation process or trigger delay,which is highly dependent on the seeding-electron density and applied voltage,and can therefore be quantitatively described by our model.Additionally,electron-beam generation is investigated by optically triggered HCD experiments on Mg-and Cu-photocathode-based devices.The results show that a more efficient trigger device is capable of generating an electron beam with higher amplitude and density.
基金Science Foundation for Distinguished Young Scholars in Tianjin,Grant/Award Number:19JCJQJC61700National Natural Science Foundation of China,Grant/Award Numbers:52327802,52173078,51973152+1 种基金National Key R&D Program of China,Grant/Award Number:2022YFB3805702State Key Program of National Natural Science Foundation of China,Grant/Award Number:52130303。
文摘Low-temperature energy harvest,delivery,and utilization pose significant challenges for thermal management in extreme environments owing to heat loss during transport and difficulty in temperature control.Herein,we propose a light-driven photo-energy delivery device with a series of photo-responsive alkoxy-grafted azobenzene-based phase-change materials(a-g-Azo PCMs).These a-g-Azo PCMs store and release crystallization and isomerization enthalpies,reaching a high energy density of 380.76 J/g even at a low temperature of-63.92℃.On this basis,we fabricate a novel three-branch light-driven microfluidic control device for distributed energy recycling that achieves light absorption,energy storage,controlled movement,and selective release cyclically over a wide range of temperatures.The a-g-Azo PCMs move remote-controllably in the microfluidic device at an average velocity of 0.11-0.53 cm/s owing to the asymmetric thermal expansion effect controlled by the temperature difference.During movement,the optically triggered heat release of a-g-Azo PCMs achieves a temperature difference of 6.6℃ even at a low temperature of-40℃.These results provide a new technology for energy harvest,delivery,and utilization in low-temperature environments via a remote manipulator.
