In order to solve the multiple power extreme value point problem caused by system frequency splitting during wireless energy transmission at short distances a transmission model of the system is established.With the c...In order to solve the multiple power extreme value point problem caused by system frequency splitting during wireless energy transmission at short distances a transmission model of the system is established.With the comprehensive consideration of the resonance frequency load parameters and the coupling between coils the internal factors of frequency splitting and boundary conditions are discussed.The results show that under the condition of the fixed load the higher the natural resonance frequency the easier the frequency splitting. As the frequency splitting occurs the frequency of the maximum power transfer is no longer with the natural resonance frequency which can make the system unstable and the transfer power more difficult to control. Therefore a decreasing-frequency method is proposed to avoid the system frequency splitting. And decreasing the system resonance frequency can make the system successfully withdraw the frequency splitting area at a short-distance range.Under the fixed load condition the transmission power of the system can be increased by 400% and the transmission efficiency is reduced by only 14% which greatly improves the transmission performance of the system.展开更多
Free electron radiation,particularly Smith-Purcell radiation,provides a versatile platform for exploring lightmatter interactions and generating light sources.A fundamental characteristic of Smith-Purcell radiation is...Free electron radiation,particularly Smith-Purcell radiation,provides a versatile platform for exploring lightmatter interactions and generating light sources.A fundamental characteristic of Smith-Purcell radiation is the monotonic decrease in radiation frequency as the observation angle increases relative to the direction of the free electrons’motion,akin to the Doppler effect.Here,we demonstrate that this fundamental characteristic can be altered in Smith-Purcell radiation generated by photonic crystals with left-handed properties.Specifically,we have achieved,to our knowledge,a novel phenomenon that the lower-frequency components propagate forward,while the higher-frequency components propagate backward,which we define as reverse Smith-Purcell radiation.Additionally,this reverse Smith-Purcell radiation can confine the radiation to a narrow angular range,which provides a way to obtain broadband light sources in a specific observation angle.Furthermore,by precisely adjusting the grating geometry and the kinetic energy of the free electrons,we can control both the radiation direction and the output frequencies.Our results provide a promising platform to study unexplored light-matter interactions and open avenues to obtain tunable,broadband light sources.展开更多
基金Scholarship Award for Excellent Doctoral Student granted by Ministry of Education of Chinathe Scientific Innovation Research of College Graduates in Jiangsu Province(No.CXZZ11-0150)+1 种基金the National Natural Science Foundation of China(No.51177011)the National High Technology Research and Development Program of China(863 Program)(No.2012AA050210)
文摘In order to solve the multiple power extreme value point problem caused by system frequency splitting during wireless energy transmission at short distances a transmission model of the system is established.With the comprehensive consideration of the resonance frequency load parameters and the coupling between coils the internal factors of frequency splitting and boundary conditions are discussed.The results show that under the condition of the fixed load the higher the natural resonance frequency the easier the frequency splitting. As the frequency splitting occurs the frequency of the maximum power transfer is no longer with the natural resonance frequency which can make the system unstable and the transfer power more difficult to control. Therefore a decreasing-frequency method is proposed to avoid the system frequency splitting. And decreasing the system resonance frequency can make the system successfully withdraw the frequency splitting area at a short-distance range.Under the fixed load condition the transmission power of the system can be increased by 400% and the transmission efficiency is reduced by only 14% which greatly improves the transmission performance of the system.
基金National Natural Science Foundation of China(61988102,62401113)Natural Science Foundation of Sichuan Province(25QNJJ2315)Fund of Key Laboratory of THz Technology,Ministry of Education。
文摘Free electron radiation,particularly Smith-Purcell radiation,provides a versatile platform for exploring lightmatter interactions and generating light sources.A fundamental characteristic of Smith-Purcell radiation is the monotonic decrease in radiation frequency as the observation angle increases relative to the direction of the free electrons’motion,akin to the Doppler effect.Here,we demonstrate that this fundamental characteristic can be altered in Smith-Purcell radiation generated by photonic crystals with left-handed properties.Specifically,we have achieved,to our knowledge,a novel phenomenon that the lower-frequency components propagate forward,while the higher-frequency components propagate backward,which we define as reverse Smith-Purcell radiation.Additionally,this reverse Smith-Purcell radiation can confine the radiation to a narrow angular range,which provides a way to obtain broadband light sources in a specific observation angle.Furthermore,by precisely adjusting the grating geometry and the kinetic energy of the free electrons,we can control both the radiation direction and the output frequencies.Our results provide a promising platform to study unexplored light-matter interactions and open avenues to obtain tunable,broadband light sources.
