Interaction of cylindrically-symmetric relativistic electron beams with planar targets and plasmas: Theory and applications

A diffusion theory for the collisional interaction of relativistic electron beams with high-atomic-number plasmas* is used to develop analytical expressions for the beam-momentum distribution function in a slab target or plasma for the case of a normally-incident, well-collimated, monoenergetic beam with any radial profile. Moments of the distribution function are calculated for a Gaussian incident profile of arbitrary width. Using these, contour plots of energy deposition and current flow are determined. Bremsstrahlung intensity profiles corresponding to pinhole photographs of tightly-pinched beams are presented for various ratios of incident beam width to electron range. Theoretical deposition profiles, current transmission, and energy coupling of beam to target are compared with the results of Monte Carlo calculations.