Bremsstrahlung from a Plasma

The effect of correlations on bremsstrahlung from a plasma is studied by using in Kirchhoff's law an absorption coefficient obtained from a Boltzmann-Fokker-Planck equation. A simple derivation of the Fokker-Planck coefficients is given by relating them to familiar dc coefficients. A dispersion formula giving the principal behavior of the absorption coefficient is obtained from a first iterate solution of the Fokker-Planck equation, treating the scattering of electrons by ions as a perturbation. The absorption coefficient reduces to the incoherent radiation result at frequencies much higher than the plasma frequency. At the plasma frequency it is greater than the incoherent absorption coefficient by a factor of O[(nλD3)12], where n is the electron density and λD is the Debye length. The effect of surface reflections on the net emission is discussed.