Beam-target interaction of intense ion beams: Theory and experiment

Work has continued toward the goal of developing and experimentally verifying a numerical model that can accurately predict the stopping power of any ion in any target material at any density, temperature, and degree of ionization. We will review our most recent theoretical work to compute the stopping power of low-Z ions in partially ionized material. We are presently attempting to develop an accurate description of the atomic-electron contribution to the stopping power, especially around the maximum of the curve. Our atomic-electron stopping-power models (e.g., the Local Oscillator Model, the Generalized Oscillator Strength Model, etc.) use realistic descriptions of atomic and solid-state charge densities and energy levels. Such modeling was successfully used in coupled deposition-hydrodynamic simulations of the NRL enhanced stopping-power experiments that were performed last year. These experiments provided the first verification of ion-stopping power enhancement in partially ionized targets and this was also the first definitive test of our stopping-power models. Further stopping-power experiments are in progress on Sandia's PROTO-I accelerator and are producing the first time-dependent measurements of the energy loss of intense ion beams via Rutherford scattering into a Thomson Parabola analyzer. We will also discuss the role of enhanced ion-stopping power in the interpretation of beam intensity diagnostics. Finally, the effects of enhanced stopping power on the design of PROTO-I and PBFA-I target experiments will be summarized.