The self-focusing/defocusing of Hermite-sinh-Gaussian (HshG) laser beam in underdense inhomogeneous plasmas is studied by using higher-order approximation theory. It is found that Hermite mode index and the fluctuation of the periodic plasma density have a significant effect on the dielectric constant and laser beam self-focusing/self-defocusing. With the increase of mode index, the high-order HshG laser beam is beneficial to suppress self-focusing and enhance self-defocusing. In addition, the effects of decentered parameters, beam intensity, and plasma non-uniformity on self-focusing/self-defocusing are discussed.

In this paper, electron acceleration by relativistic pondermotive force has been studied in the interaction of intense laser pulse with an axially inhomogeneous underdense plasma. The results show that the relativistic ponderomotive nonlinearity causes obvious beam self-focusing and a highly energetic electron can be achieved in the plasma, moreover, the high-energy electron would be automatically ejected by the ponderomotive force without adding any additional extractor. In addition, it is found that the real part and imaginary part of Lorentz factor can directly affect the amplitude and change the trend of electron acceleration, and electrons acceleration can be strengthened when we can elect properly the laser intensity with higher momentum and smaller beam width, but nonuniformity of plasmas can slightly decrease the electron acceleration. The results can provide useful physical support for novel design of table accelerator and the optimized parameters of electron acceleration in the plasma.

No abstract