We have studied the ion emission in the interaction between femtosecond laser pulses and solid targets by experiments and particle-in-cell(PIC)simulations.We found experimentally that almost all of the fast ions are c...We have studied the ion emission in the interaction between femtosecond laser pulses and solid targets by experiments and particle-in-cell(PIC)simulations.We found experimentally that almost all of the fast ions are confined within a cone symmetrically around the normal direction of targets.The PIC simulation results demonstrate that the fast ion beam can be accelerated by the laser-induced electrostatic field in front of solid targets.展开更多
Recent experiments have observed magnetic reconnection in laser-produced high-energy-density(HED)plasma bubbles.We perform two-dimensional(2-D)particle-in-cell(PIC)simulations to investigate magnetic reconnection betw...Recent experiments have observed magnetic reconnection in laser-produced high-energy-density(HED)plasma bubbles.We perform two-dimensional(2-D)particle-in-cell(PIC)simulations to investigate magnetic reconnection between two approaching HED plasma bubbles.It is found that the expanding velocity of the bubbles has a great influence on the process of magnetic reconnection.When the expanding velocity is small,a single X line reconnection is formed.However,when the expanding velocity is sufficiently large,we can observe a plasmoid in the vicinity of the X line.At the same time,the structures of the electromagnetic field in HED plasma reconnection are similar to that in Harris current sheet reconnection.展开更多
We propose a new single-shot method for measuring terahertz pulses using a linearly chirped optical pulse interferogram.Modulated frequency domain phase information can be extracted by the interferogram recorded on im...We propose a new single-shot method for measuring terahertz pulses using a linearly chirped optical pulse interferogram.Modulated frequency domain phase information can be extracted by the interferogram recorded on imaging spectrographs.The terahertz pulse waveform is obtained from the phase information.We overcome the energy fluctuation problem by using the phase information,making a reference shot unnecessary and the terahertz detection more flexible and convincing.展开更多
The emission lines of B,C,O and Fe in tokamak plasma are reported.The spectra are compared with those calculated by the CHIANTI code,which is based on the collisional-radiative models with a large amount of accurate a...The emission lines of B,C,O and Fe in tokamak plasma are reported.The spectra are compared with those calculated by the CHIANTI code,which is based on the collisional-radiative models with a large amount of accurate atomic data.General agreement is obtained between the results of experiment and computation.Most of the lines in the spectra are identified,and the relative number density ratios of B,C,O and Fe are determined.It is found that the processes of line formation in our experiment are similar to those in the stellar coronae.The line-averaged electron density of the tokamak plasma is measured by the HCN laser,indicating a good agreement with the theoretical prediction by the density-dependent line ratio of Fe XXI.展开更多
We study the quasibound states in a graphene quantum-dot structure generated by the single-, double-, and triple-barrier electrostatic potentials. It is shown that the strongest quasibound states are mainly determined...We study the quasibound states in a graphene quantum-dot structure generated by the single-, double-, and triple-barrier electrostatic potentials. It is shown that the strongest quasibound states are mainly determined by the innermost barrier. Specifically, the positions of the quasibound states are determined by the barrier height, the number of the quasibound states is determined by the quantum-dot radius and the angular momentum, and the localization degree of the quasibound states is influenced by the width of the innermost barrier, as well as the outside barriers. Furthermore, according to the study on the double- and triple-barrier quantum dots, we find that an effective way to generate more quasibound states with even larger energy level spacings is to design a quantum dot defined by many concentric barriers with larger barrier-height differences. Last, we extend our results into the quantum dot of many barriers, which gives a complete picture about the formation of the quasibound states in the kind of graphene quantum dot created by many concentric potential barrier rings.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos.19825110,10005014,and 10075075the National Key Basic Research Special Foundation(NKBRSF)(Grant No.G1999075200).
文摘We have studied the ion emission in the interaction between femtosecond laser pulses and solid targets by experiments and particle-in-cell(PIC)simulations.We found experimentally that almost all of the fast ions are confined within a cone symmetrically around the normal direction of targets.The PIC simulation results demonstrate that the fast ion beam can be accelerated by the laser-induced electrostatic field in front of solid targets.
基金the National Natural Science Foundation of China under Grant Nos 11220101002,41174124,41274144 and 41121003the Key Research Program of Chinese Academy of Sciences(KZZD-EW-01)+1 种基金the National Basic Research Program of China(2012CB825602)the Ocean Public Welfare Scientific Research Project,State Oceanic Administration of China(No 201005017).
文摘Recent experiments have observed magnetic reconnection in laser-produced high-energy-density(HED)plasma bubbles.We perform two-dimensional(2-D)particle-in-cell(PIC)simulations to investigate magnetic reconnection between two approaching HED plasma bubbles.It is found that the expanding velocity of the bubbles has a great influence on the process of magnetic reconnection.When the expanding velocity is small,a single X line reconnection is formed.However,when the expanding velocity is sufficiently large,we can observe a plasmoid in the vicinity of the X line.At the same time,the structures of the electromagnetic field in HED plasma reconnection are similar to that in Harris current sheet reconnection.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10925421 and 10734130.
文摘We propose a new single-shot method for measuring terahertz pulses using a linearly chirped optical pulse interferogram.Modulated frequency domain phase information can be extracted by the interferogram recorded on imaging spectrographs.The terahertz pulse waveform is obtained from the phase information.We overcome the energy fluctuation problem by using the phase information,making a reference shot unnecessary and the terahertz detection more flexible and convincing.
基金by the National Natural Science Foundation of China under Grant Nos 10821061,10876040,10925421 and 10734130the Chinese Academy of Sciences under Grant No KJCX2-YW-T01the National Basic Research Program of China under Grant No 2007CB815103.
文摘The emission lines of B,C,O and Fe in tokamak plasma are reported.The spectra are compared with those calculated by the CHIANTI code,which is based on the collisional-radiative models with a large amount of accurate atomic data.General agreement is obtained between the results of experiment and computation.Most of the lines in the spectra are identified,and the relative number density ratios of B,C,O and Fe are determined.It is found that the processes of line formation in our experiment are similar to those in the stellar coronae.The line-averaged electron density of the tokamak plasma is measured by the HCN laser,indicating a good agreement with the theoretical prediction by the density-dependent line ratio of Fe XXI.
基金supported by the National Natural Science Foundation of China (Grant Nos.10974015 and 11074297)the Program for New Century Excellent Talents in University (Grant No.NCET-08-0044)
文摘We study the quasibound states in a graphene quantum-dot structure generated by the single-, double-, and triple-barrier electrostatic potentials. It is shown that the strongest quasibound states are mainly determined by the innermost barrier. Specifically, the positions of the quasibound states are determined by the barrier height, the number of the quasibound states is determined by the quantum-dot radius and the angular momentum, and the localization degree of the quasibound states is influenced by the width of the innermost barrier, as well as the outside barriers. Furthermore, according to the study on the double- and triple-barrier quantum dots, we find that an effective way to generate more quasibound states with even larger energy level spacings is to design a quantum dot defined by many concentric barriers with larger barrier-height differences. Last, we extend our results into the quantum dot of many barriers, which gives a complete picture about the formation of the quasibound states in the kind of graphene quantum dot created by many concentric potential barrier rings.
