Free electron laser in magnetically dominated regime: simulations with ONEDFEL code

Using the ONEDFEL code we perform Free Electron Laser simulations in the astrophysically important guide-field dominated regime. For wigglers' (Alfven waves) wavelengths of tens of meters and beam Lorentz factor $\sim 10^3$, the resulting coherently emitted waves are in the centimeter range. Our simulations show a growth of the wave intensity over fourteen orders of magnitude, over the astrophysically relevant scale of $\sim$ few kilometers. The signal grows from noise (unseeded). The resulting spectrum shows fine spectral sub-structures, reminiscent of the ones observed in Fast Radio Bursts (FRBs).