Measurement of proton, lithium, and fluorine ion energy densities on PBFA II

Summary form only given, as follows. In the light-ion-beam fusion program at Sandia National Laboratories an intense lithium beam is being developed to drive inertial confinement fusion targets. An important parameter of this lithium beam is its purity. To reduce potential contamination of the lithium beam by protons, carbon, and oxygen (due to residual hydrocarbons and gases in the system) significant improvements to the vacuum system of the Particle Beam Fusion Accelerator II (PBFA II) have been made and in-situ methods of cleaning the anode ion source have been introduced. To help assess the effectiveness of these improvements on reducing the impurities in the lithium beam we have developed and fielded new, nuclear activation diagnostics for measuring the individual energy densities of lithium, protons, and fluorine (from LiF anode sources) in the beam. The specific reactions upon which these diagnostics are based are discussed in another paper at this meeting. To help retain any ablation products, the target materials are fielded in enshrouded cans (pepper shakers) having only a small pin hole opening (area=0.0613 cm/sup 2/) through which a small fraction of the ion beam enters. In the diode, we typically field three vertical rows of five pepper shakers each at a radius of 12.3 cm and at azimuthal angles of 105/spl deg/, 195/spl deg/, and 285/spl deg/. Using these diagnostics we have measured the energy densities of lithium, protons, and fluorine at each pepper shaker location. These data give an indication of both the uniformity of the beam and the fraction of proton and fluorine impurities in the lithium beam. The results of these measurements will be presented.