Intense, broadband far-IR/THZ radiation from the Jlab FEL

The authors calculate the spectral output from a dipole magnet in the energy recovery system of the Jefferson Laboratory Free Electron Laser (FEL) in the 1--10,000 cm{sup {minus}1} (1 micron to 1 cm) range. They show that due to multiparticle coherent enhancement (coherent synchrotron radiation or CSR), the emission contains almost 1 watt/cm{sup {minus}1} of power emitted into the diffraction limit. For the purpose of this illustrative calculation they assume some typical parameters for the machine, namely that they have 100 pico-coulomb electron bunches at a 37.4 MHz repetition rate. They also assumed full width half maximum (fwhm) horizontal and vertical beam sizes of 200 microns. They took the electron beam energy to be 40 MeV, the bending radius to be 1m, and they extracted 90 x 90 milliradians of light (approximately an {line_integral}/11 beam)