We study the near-field response of a shell nanocylinder pair, with its core filled by gain materials, using a two- dimensional finite-difference time-domain method. It is shown that the gain materials in the core of ...We study the near-field response of a shell nanocylinder pair, with its core filled by gain materials, using a two- dimensional finite-difference time-domain method. It is shown that the gain materials in the core of the cylinder can compensate for the intrinsic absorption of the metal shell, leading to local-field enhancement in the gap of the active pair. A linear dependence is found between the field enhancement and the gain coefficient at resonance. The detailed physics is studied by calculating the electrical-field distribution of the shell pair filled with different gain materials. The influence of the gap width and the shell thickness on the interaction of two adjacent active shell cylinders is also investigated.展开更多
The error field penetration is numerically studied in the frame of the visco-resistive magnetohydrodynamics(MHD) model.A transition scaling is obtained to link the Rutherford and Waelbroeck regimes in the nonlinear ...The error field penetration is numerically studied in the frame of the visco-resistive magnetohydrodynamics(MHD) model.A transition scaling is obtained to link the Rutherford and Waelbroeck regimes in the nonlinear phase of error field penetration process.Furthermore,a transition density scaling of[br/BT]critne1/2 obtained in accord with recent experimental observations in the J-TEXT tokamak.展开更多
The effects of out-of-plane shear flows on fast magnetic reconnection are numerically investigated by a two- dimensional (2D) hybrid model in an initial Harris sheet equilibrium with flows. The equilibrium and drive...The effects of out-of-plane shear flows on fast magnetic reconnection are numerically investigated by a two- dimensional (2D) hybrid model in an initial Harris sheet equilibrium with flows. The equilibrium and driven shear flows out of the 2D reconnection plane with symmetric and antisymmetric profiles respectively are used in the simulation. It is found that the out-of-plane flows with shears in-plane can change the quadrupolar structure of the out-of-plane magnetic field and, therefore, modify the growth rate of magnetic reconnection. Furthermore, the driven flow varying along the anti-parallel magnetic field can either enhance or reduce the reconnection rate as the direction of flow changes. Secondary islands are also generated in the process with converting the initial X-point into an O-point.展开更多
We investigate optical properties of a bowtie-shaped aperture using the finite difference time domain method to optimize its geometric parameters for specific incident lights. The influence of the parameters on local ...We investigate optical properties of a bowtie-shaped aperture using the finite difference time domain method to optimize its geometric parameters for specific incident lights. The influence of the parameters on local field enhancement and resonant wavelength in the visible frequency range is numerically analysed. It is found that the major resonance of the spectrum is exponentially depended on the bowtie angle but independent of the whole aperture size. The simulation also demonstrates that increasing the aperture size raises the local field intensity on the exit plane due to an enlarged interaction area between the light and the metal medium. And the near-field spot size is closely related to the gap. Based on these results, the design rules of the bowtie structure can be optimized for specific wavelengths excited.展开更多
基金Project support by the National Natural Science Foundation of China (Grant Nos. 10975012 and 11074029)
文摘We study the near-field response of a shell nanocylinder pair, with its core filled by gain materials, using a two- dimensional finite-difference time-domain method. It is shown that the gain materials in the core of the cylinder can compensate for the intrinsic absorption of the metal shell, leading to local-field enhancement in the gap of the active pair. A linear dependence is found between the field enhancement and the gain coefficient at resonance. The detailed physics is studied by calculating the electrical-field distribution of the shell pair filled with different gain materials. The influence of the gap width and the shell thickness on the interaction of two adjacent active shell cylinders is also investigated.
基金supported by the National Magnetic Confinement Fusion Science Program of China(Nos.2014GB124001 and 2013GB102000)National Natural Science Foundation of China(Nos.11322549,11275043 and 11275080)
文摘The error field penetration is numerically studied in the frame of the visco-resistive magnetohydrodynamics(MHD) model.A transition scaling is obtained to link the Rutherford and Waelbroeck regimes in the nonlinear phase of error field penetration process.Furthermore,a transition density scaling of[br/BT]critne1/2 obtained in accord with recent experimental observations in the J-TEXT tokamak.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.10935004,1126114032,10778613,10575018,40731056,10975012,and 11261140326)
文摘The effects of out-of-plane shear flows on fast magnetic reconnection are numerically investigated by a two- dimensional (2D) hybrid model in an initial Harris sheet equilibrium with flows. The equilibrium and driven shear flows out of the 2D reconnection plane with symmetric and antisymmetric profiles respectively are used in the simulation. It is found that the out-of-plane flows with shears in-plane can change the quadrupolar structure of the out-of-plane magnetic field and, therefore, modify the growth rate of magnetic reconnection. Furthermore, the driven flow varying along the anti-parallel magnetic field can either enhance or reduce the reconnection rate as the direction of flow changes. Secondary islands are also generated in the process with converting the initial X-point into an O-point.
基金Project supported by the National Natural Science Foundation of China (Grant No. 10975012)
文摘We investigate optical properties of a bowtie-shaped aperture using the finite difference time domain method to optimize its geometric parameters for specific incident lights. The influence of the parameters on local field enhancement and resonant wavelength in the visible frequency range is numerically analysed. It is found that the major resonance of the spectrum is exponentially depended on the bowtie angle but independent of the whole aperture size. The simulation also demonstrates that increasing the aperture size raises the local field intensity on the exit plane due to an enlarged interaction area between the light and the metal medium. And the near-field spot size is closely related to the gap. Based on these results, the design rules of the bowtie structure can be optimized for specific wavelengths excited.