Experimental investigations on the vacuum outgassing of a carbon nanotube （CNT） cathode with high-intensity pulsed electron emission on a 2 MeV linear induction accelerator injector are presented. Under the 1.60 MV ...Experimental investigations on the vacuum outgassing of a carbon nanotube （CNT） cathode with high-intensity pulsed electron emission on a 2 MeV linear induction accelerator injector are presented. Under the 1.60 MV diode voltage, the CNT cathode could provide 1.67 kA electron beam with the amount of outgassing of about 0.51 Pa.L. It is found that the amount of outgassing, which determines the cathode emission current, depends on the diode voltage and the vacuum.展开更多
Carbon nanotube（CNT） cathodes prepared by electrophoretic deposition were treated by a combination of nickel electroplating and cathode corrosion technologies.The characteristics of the samples were measured by scan...Carbon nanotube（CNT） cathodes prepared by electrophoretic deposition were treated by a combination of nickel electroplating and cathode corrosion technologies.The characteristics of the samples were measured by scanning electron microscopy,energy dispersive X-ray spectroscopy,J-E and F-N plots.After the treatment,the CNT cathodes showed improved field emission properties such as turn-on field,threshold electric field,current density,stability and luminescence uniformity.Concretely,the turn-on field decreased from 0.95 to 0.45 V/μm at an emission current density of 1 mA/cm^2,and the threshold electric field decreased from 0.99 to 0.46 V/μm at a current density of 3 mA/cm^2.The maximum current density was up to 7 mA/cm2 at a field of 0.48 V/μm.In addition,the current density of the CNT cathodes fluctuated at around 0.7 mA/cm^2 for 20 h,with an initial current density 0.75 mA/cm^2.The improvement in field emission properties was found to be due to the exposure of more CNT tips,the wider gaps among the CNTs and the infiltration of nickel particles.展开更多
A dual functional CNTs@graphene/CNTs cathode for Li–Se battery was constructed by a CNTs@graphene network and a CNTs interlayer. CNTs were first integrated with graphene to form a three-dimensional（3D） framework an...A dual functional CNTs@graphene/CNTs cathode for Li–Se battery was constructed by a CNTs@graphene network and a CNTs interlayer. CNTs were first integrated with graphene to form a three-dimensional（3D） framework and work together as a conductive matrix for Se confinement. The optimized composite cathode delivers a high initial capacity of 575 mAh·g^-1 at 0.5 A·g^-1 and good rate capacity with a retained capacity of 479 mAh·g^-1 at 2.0 A·g^-1（73% of the capacity at 0.2 A·g^-1）. CNTs were further served as an interlayer to confine the diffusion of polyselenides by constructing a thin CNTs layer outside the CNTs@graphene network. An improved initial capacity of 616 mAh·g^-1 at 0.5 A·g^-1 is achieved with a retained capacity of 538 mAh·g^-1 after 80 cycles, indicating the effective dual function of CNTs in this novel cathode construction and great application potential for Li–Se battery.展开更多
文摘Experimental investigations on the vacuum outgassing of a carbon nanotube （CNT） cathode with high-intensity pulsed electron emission on a 2 MeV linear induction accelerator injector are presented. Under the 1.60 MV diode voltage, the CNT cathode could provide 1.67 kA electron beam with the amount of outgassing of about 0.51 Pa.L. It is found that the amount of outgassing, which determines the cathode emission current, depends on the diode voltage and the vacuum.
基金Project supported by the National High Technology Research and Development Program of China(No.2008AA03A313)the National Natural Science Foundation of China(No.61106053)the Specialized Research Fund for the Doctoral Program of Higher Education of China(No.20103514110007)
文摘Carbon nanotube（CNT） cathodes prepared by electrophoretic deposition were treated by a combination of nickel electroplating and cathode corrosion technologies.The characteristics of the samples were measured by scanning electron microscopy,energy dispersive X-ray spectroscopy,J-E and F-N plots.After the treatment,the CNT cathodes showed improved field emission properties such as turn-on field,threshold electric field,current density,stability and luminescence uniformity.Concretely,the turn-on field decreased from 0.95 to 0.45 V/μm at an emission current density of 1 mA/cm^2,and the threshold electric field decreased from 0.99 to 0.46 V/μm at a current density of 3 mA/cm^2.The maximum current density was up to 7 mA/cm2 at a field of 0.48 V/μm.In addition,the current density of the CNT cathodes fluctuated at around 0.7 mA/cm^2 for 20 h,with an initial current density 0.75 mA/cm^2.The improvement in field emission properties was found to be due to the exposure of more CNT tips,the wider gaps among the CNTs and the infiltration of nickel particles.
基金financially supported by the National Basic Research Program of China(No.2014CB932400)the National Science Foundation of China(Nos.21406161 and 51602220)
文摘A dual functional CNTs@graphene/CNTs cathode for Li–Se battery was constructed by a CNTs@graphene network and a CNTs interlayer. CNTs were first integrated with graphene to form a three-dimensional（3D） framework and work together as a conductive matrix for Se confinement. The optimized composite cathode delivers a high initial capacity of 575 mAh·g^-1 at 0.5 A·g^-1 and good rate capacity with a retained capacity of 479 mAh·g^-1 at 2.0 A·g^-1（73% of the capacity at 0.2 A·g^-1）. CNTs were further served as an interlayer to confine the diffusion of polyselenides by constructing a thin CNTs layer outside the CNTs@graphene network. An improved initial capacity of 616 mAh·g^-1 at 0.5 A·g^-1 is achieved with a retained capacity of 538 mAh·g^-1 after 80 cycles, indicating the effective dual function of CNTs in this novel cathode construction and great application potential for Li–Se battery.
