Numerical investigation of plasma heating during the entrance of an intense short laser pulse into a density profile

Abstract

In this paper, plasma heating is numerically investigated using a 1D-3V particle-in-cell simulation code through the interaction between an intense short laser pulse with temporal duration, τ L = 60 fs, and a plasma having a slightly overcritical bulk density and an exponential pre-plasma density profile. The aim is to identify, via suitable parametric analysis, the most relevant nonlinear mechanisms as a function of the system parameters. As key points of our research, simulation results revealed that, for pulse-lengths less than the local nonlinear plasma wavelength, L p λ nl p , mechanisms such as vacuum-plasma interface wave-break and longitudinal plasma oscillations are the dominant mechanisms for the initiation of electron acceleration and plasma heating at earlier times. Further, for variable density scale lengths our results have proven that the heating mechanisms mentioned above can be ignored for the laser intensities less than a specific threshold value, a 0 < 3, even for short density scale length, L p = 3 µm. Meanwhile, by increasing the laser intensity to higher values, it is observed that the trend of the time history curve for the mean temperature changed in a way that the total level of temperature increased. Also, by lengthening the scale length, at first the amounts of the mean temperature curve increased, and then smoothly decreased.

Effects of laser waveform on the generation of fast electrons in laser–solid interactions

“…The coupling efficiency of laser energy can be further improved and the fast electron divergence angle can be optimized by an external magnetic field [10] . For laser parameters, theoretical and experimental studies have mainly focused on the influence of laser energy, intensity, pulse width, and polarization [11][12][13][14][15] .…”