Nonlinear Thomson scattering of intense laser pulses from beams and plasmas

A comprehensive theory is developed to describe the nonlinear Thomson scattering of intense laser fields from beams and plasmas. This theory is valid for linearly or circularly polarized incident laser fields of arbitrary intensities and for electrons of arbitrary energies. Explicit expressions for the intensity distributions of the scattered radiation are calculated and numerically evaluated. The space-charge electrostatic potential, which is important in high-density plasmas and prevents the axial drift of electrons, is included self-consistently. Various properties of the scattered radiation are examined, including the linewidth, angular distribution, and the behavior of the radiation spectra at ultrahigh intensities. Nonideal effects, such as electron-energy spread and beam emittance, are discussed. A laser synchrotron source (LSS), based on nonlinear Thomson scattering, may provide a practical method for generating tunable, near-monochromatic, well-collimated, short-pulse x rays in a compact, relatively inexpensive source. Two examples of possible LSS configurations are presented: an electron-beam LSS generating hard (30-keV, 0.4-Å) x rays and a plasma LSS generating soft (0.3-keV, 40-Å) x rays. These LSS configurations are capable of generating ultrashort (∼1-ps) x-ray pulses with high peak flux (≳10²¹ photons/s) and brightness [≳10¹⁹ photons /(s mm² mrad²), 0.1% bandwidth].