Bremsstrahlung from fully stripped tungsten (W74+) in a Debye-Hückel potential

Abstract

Based on the exact relativistic multipole calculations using pure Coulomb and Debye-H\"uckel potentials, discussions of bremsstrahlung cross sections and corresponding emitted photon angular distributions from fully stripped tungsten (${\mathrm{W}}^{74+}$) are given for electron scattering at energies of 10--150 keV. Nonrelativistic dipole calculations are also presented, showing that for the above energy region, the nonrelativistic results are completely invalid and the relativistic and multipole effects must be taken into account. The reduction of bremsstrahlung cross sections due to screening of the nuclear charge is studied using the relativistic multipole method at different values of the screening length and photon energy. With an increase of electron scattering energy, the effect of the screening potential on both the dynamics of fast free electrons and the cross sections is reduced. The peak of the angular distribution of bremsstrahlung would shift towards smaller emission angles when the screening strength is reduced.