Numerical simulations of THz emission from the laser interaction with magnetized plasmas

One-dimensional particle-in-cell (PIC) program is used to simulate the generation of high power terahertz (THz) emission from the interaction of an ultrashort intense laser pulse with underdense magnetized plasma. The spectra of THz radiation are discussed with different laser intensity, pulse width, density scale length and external magnetic field. A high-amplitude electron plasma wave driven by a laser pulse can produce powerful THz emission through linear mode conversion under certain conditions. With incident laser intensity of 1018 W/cm2, the generated emission is computed to be of the order of several MV/cm field and tens of MW level power. The corresponding energy converrsion efficiency is several ten thousandths, which is higher than the efficiency of other THz source and suitable for the studies of high-field and nonlinear physics in the THz regime.