Analysis of ion focusing parameters PBFA-II

Summary form only given. An important aspect of the ion ICF (inertial confinement fusion) program is the determination of focused intensity of ions onto a central target on PBFA-II (Particle Beam Fusion Accelerator II). A filtered six-frame camera has been fielded which images the ions Rutherford scattered from a thin gold foil at the center of the PBFA-II diode. Since the track size is a sensitive function of the voltage, the rapidly decreasing voltage of the applied-B ion diode combined with the high-resolution VERA track counting system enables this diagnostic to provide 5-15-ns resolution of the focused ion beam. The relationship between the measured images and the ion focus has been studied extensively using Monte Carlo techniques to permit direct correlations between the ion images and the focal intensity. Recent analysis of these images using automated analysis techniques has indicated some surprising results. When only ions with a small spread in energy are considered, focal widths and heights of ~3.5 mm full width at half maximum are measured on the better shots