Direct nuclear activation diagnostics of intense ion beams on PBFA IIX

Summary form only given, as follows. In 1995 the Particle Beam Fusion Accelerator was converted from a barrel diode to an extraction diode configuration. This new configuration, termed PBFA IIX, gives greater access to the diode which has resulted in higher shot rates; allows higher voltage operation; and is compatible with beam propagation which will be necessary to field high-yield, inertial-confinement-fusion targets. The extraction anode consists of a flat, annular ring. We have fielded a variety of nuclear activation diagnostics to help assess the performance of this diode. The primary activation diagnostic allows us to estimate the hydrogen and lithium beam energy densities by measuring the products of the reactions: /sup 7/Li(p,n)/sup 7/Be, /sup 10/B(p,/spl alpha/)/sup 7/Be, and /sup 19/F(/sup 7/Li,d)/sup 24/Na. The activation target consists of LiF housed in a can having a small (0.0613 cm/sup 2/) hole through which a fraction of the beam can enter and irradiate the target. This geometry helps to retain any ablated products which must be counted if an accurate measurement is to be made. By fielding an array of these "pepper shaker" activation samples, we also obtain a measure of the spatial variations in the beam. With another activation diagnostic, we have estimated peak ion energies using the range filter technique. In this technique we use metal filters of known thickness to determine the maximum filter depth that a proton can penetrate and still activate titanium via the reaction: /sup 48/Ti(p,n)/sup 48/V. From the stopping power relationship between protons and the filter material and the threshold of the titanium reaction (4.9 MeV), the approximate peak proton ion energy can be estimated.