The laser pulse modulation instabilities in partially stripped plasma were discussed based on the phase and group velocities of the laser pulse and the two processes that modulation instabilities excited. The excitati...The laser pulse modulation instabilities in partially stripped plasma were discussed based on the phase and group velocities of the laser pulse and the two processes that modulation instabilities excited. The excitation condition and growth rate of the modulation instability were obtained. It was found that the positive chirp and competition between normal and abnormal dispersions play important roles in the modulation instability. In the partially stripped plasma, the increased positive chirp enhances the modulation instability, and the dispersion competition reduces it.展开更多
One dimensional electron density perturbation is derived by using the cold fluid equation, Possion's equation and the continuity equation. The perturbation is generated by a driving laser pulse propagating through...One dimensional electron density perturbation is derived by using the cold fluid equation, Possion's equation and the continuity equation. The perturbation is generated by a driving laser pulse propagating through a plasma. The upshifting of the frequency of a trailing pulse induced by density perturbation is studied by using optical metric. The results show that it is possible that the photon will gain energy from the wakefield when assuming photon's number to be conserved, i.e. , the photon will be accelerated.展开更多
Laser Wakefield is produced by ultra-high intensity laser pulse interacting with underdense plasma with special conditions for the laser wavelength and plasma density. In this mechanism, nonlinear forces appear due to...Laser Wakefield is produced by ultra-high intensity laser pulse interacting with underdense plasma with special conditions for the laser wavelength and plasma density. In this mechanism, nonlinear forces appear due to the very high amplitudes of the electromagnetic wave and these forces evacuate plasma electrons from the path of the laser pulse leading to very high electron plasma density gradients. Due to the electrostatic forces which result from these density perturbations, the electrons move very fast in oscillatory manner to restore neutrality creating a wake of electron density perturbations behind the laser pulse. Detailed investigation has been dealt with the time-delay between the driver laser pulse and the probe pulse which can affect the production of high plasma gradients needed for photon acceleration process.展开更多
基金Project supported by the National Natural Science Foundation of China （Grant No 10276002）.
文摘The laser pulse modulation instabilities in partially stripped plasma were discussed based on the phase and group velocities of the laser pulse and the two processes that modulation instabilities excited. The excitation condition and growth rate of the modulation instability were obtained. It was found that the positive chirp and competition between normal and abnormal dispersions play important roles in the modulation instability. In the partially stripped plasma, the increased positive chirp enhances the modulation instability, and the dispersion competition reduces it.
文摘One dimensional electron density perturbation is derived by using the cold fluid equation, Possion's equation and the continuity equation. The perturbation is generated by a driving laser pulse propagating through a plasma. The upshifting of the frequency of a trailing pulse induced by density perturbation is studied by using optical metric. The results show that it is possible that the photon will gain energy from the wakefield when assuming photon's number to be conserved, i.e. , the photon will be accelerated.
文摘Laser Wakefield is produced by ultra-high intensity laser pulse interacting with underdense plasma with special conditions for the laser wavelength and plasma density. In this mechanism, nonlinear forces appear due to the very high amplitudes of the electromagnetic wave and these forces evacuate plasma electrons from the path of the laser pulse leading to very high electron plasma density gradients. Due to the electrostatic forces which result from these density perturbations, the electrons move very fast in oscillatory manner to restore neutrality creating a wake of electron density perturbations behind the laser pulse. Detailed investigation has been dealt with the time-delay between the driver laser pulse and the probe pulse which can affect the production of high plasma gradients needed for photon acceleration process.
