Numerical simulation of the heating of planar targets in PBFA-II Li beam experiments

In Particle Beam Fusion Accelerator-II (PFBA-II) experiments at Sandia National Laboratories, intense beams of 10 MeV Li ions are focused onto targets, heating them to tens of eV. The pulse width of the Li beams is 15--20 nsec, and the peak power and current densities at the target are 1--2 TW/cm2 and 0.2--0.4 MA/cm2, respectively. Numerical simulations of the heating of thin plastic sandwich targets composed of CH/Al/Au/CH layers are performed using a 1-D radiation-hydrodynamics code. Energy deposition by the beam is modeled using a stopping power model which includes the effects of both bound and free electrons. A detailed line radiation transport model is used to calculate radiation losses from the lower-Z regions. Plasma temperatures are deduced by analyzing inner-shell emission spectra observed from the Al. The goal of the study is to develop a good understanding of the essential physics of the experiments by obtaining a consistent picture between the temperature deduced from the Al Kα satellite spectra, the ion beam diagnostics, and the radiation-hydrodynamics simulations