Electromagnetic pulse generation from laser-plasma interactions

Electromagnetic particle-in-cell simulations show that laser-plasma interactions generate a radially propagating and axially polarized electromagnetic pulse, oscillating near the plasma frequency. This EMP and the electrostatic plasma wakefield are replicated with a ponderomotively-driven reduced model which, by eliminating unessential physics, indicates that the EMP can be generated independent of previously reported mechanisms such as external fields, nonuniform densities, and oblique or two-colored lasers. In addition to providing much faster simulations with less computational noise than the PIC simulations, the reduced model also allows for the calculation of the energy lost from the drive laser to the electrostatic wakefield and EMP. The simulations show that the EMP energy varies inversely with the pulse's transverse width, when normalized by the laser energy, while the wakefield energy is largely independent of pulse width.