| The study on laser interacting with plasma achieves rapid development because of the rapid development of laser technology, especially the appearance of ultra- intense ultra-short laser pulse. The stable propagation of an intense laser pulse in plasma is important in a number of applications including laser-driven accelerators, laser-fusion and high-order harmonic generation, etc. So, the study of propagating mechanisms of the laser pulse in plasma has already become a hot topic. On the other hand, the achievement of high quality hard electron by laser pulse interacting with plasma has attracted many attentions because of they have many prospective applications in practice, such as fast ignition of inertial confinement fusion and the generation of X-ray etc. In this paper author has researched mainly two topics of laser interacting with plasma.1. The propagation characteristics of an intense laser pulse with length L =p? in a parabolic preformed plasma channel was investigated in detail when the effects of higher-order relativistic nonlinearity(HRN) and wakefield were taken into account. The evolution equation of the laser spot size was obtained by a variational technique. The comparisons among the effects of HRN, transverse wakefield(TWF) and longitudinal wakefield(LWF) are illustrated numerically, respectively.2. Electron acceleration and wakefield evolution of the bubble with adding a dense-plasma wall in the under-dense plasma were investigated by two-dimensional particle-in-cell(PIC) simulations. The mode transition from laser wakefield acceleration(LWFA) to plasma wakefield acceleration(PWFA) was discussed in detail. Because of the lengthways contraction of wakefield, the self-injected electron bunches were quasi phase-stable accelerated during the LWFA stage. As the laser pulse was dissipated, the plasma wakefield driven by self-injected bunches trapped and accelerated the electrons in channel. Two beams of high quality electrons were gained finally. |
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