PIC Simulation Of Plasma Grating In Ultra-intense Lasers

High field science has become one of the hottest research fields in physics since the appearance of CPA(chirped pulse amplification) technology. Among them, the inter-action between intense laser fields and plasma has attracted much attention. In this thesis, we will use PIC codes to study the forming and dynamical properties of the plasma density grating once the two counter-propagating intense laser pulses meet each other in the preformed plasma. The software package we are using is VORPAL. The main results we have obtained are summarized as follows.1. If the density of the preformed plasma is low, there is little coupling between the electrons and ions. Hence the ions is almost motionless. The grating is formed by the electrons and will show as a oscillating grating. On the other hand, if the plasma density is increased, a strong coupling between electrons and ions can be observed. Now the electrons and ions will oscillate together. The plasma grating is now composed of both particles and thus shows as a stationary grating. For example, when two counter-propagating plane wave pulses with wavelength266nm interact with each other in the plasma region. For a laser intensity of1015W/cm2and the plasma density of0.004nc, a oscillating grating will be generated. On the otherhand, when the laser intensity is1016W/cm2and the plasma density is0.1nc, a stable grating will be produced.2. Once the plasma grating is formed, it will greatly affect the following laser/plasma interaction. For example, if an infrared laser pulse enters the plasma grating re-gion, the electron energy density in the peak of the plasma density grating will be much greater than the one without a plasma density grating.3. The forming of the grating will also greatly increase the absorption ability of the laser energies in the plasma.