Nonrelativistic Electron–Ion Bremsstrahlung: An Approximate Formula for All Parameters

The evaluation of the electron-ion bremsstrahlung cross section exact to all orders in Coulomb potential is computationally expensive due appearance hypergeometric functions. Therefore tabulations are widely used. Here, we provide an approximate formula for non-relativistic dipole process valid applicable relative velocities and photon energies. Its validity spans from Born- classical regime soft-photon emission kinematic endpoint. error remains below 3% (and 1%) except at isolated region hard-photon quantum-to-classical crossover. We use obtain thermally averaged spectrum cooling function a Maxwellian plasma demonstrate that they accurate better than 2%.