２dimensional PIC simulation of the generation of wakefield

We analysis the wakefield generation and the electrons acceleration when ultraintense short laser pulse propagate through tenuous plasma with 2D3V PIC simulation model．The effects of FRS elongates the length of the laser pulse as well as steeps the tail of the pulse which results in the notable reduces of the electrostatic phase velocity and maximum electron kinetic energy achieved when traped．At the same time the most effective length of the laser pulse to stimulate the wake-field becomes longer.