Collection of solid and gaseous samples to diagnose inertial confinement fusion implosions.
Collection of representative samples of debris following inertial confinement fusion implosions in order to diagnose implosion conditions and efficacy is a challenging endeavor because of the unique conditions within the target chamber such as unconverted laser light, intense pulse of x-rays, physical chunks of debris, and other ablative effects. We present collection of gas samples following an implosion for the first time. High collection fractions for noble gases were achieved. We also present collection of solid debris samples on flat plate collectors. Geometrical collection efficiencies for Au hohlraum material were achieved and collection of capsule debris (Be and Cu) was also observed. Asymmetric debris distributions were observed for Au and Be samples. Collection of Be capsule debris was higher for solid collectors viewing the capsule through the laser entrance hole in the hohlraum than for solid collectors viewing the capsule around the waist of the hohlraum. Collection of Au hohlraum material showed the opposite pattern: more Au debris was collected around the waist than through the laser entrance hole. The solid debris collectors were not optimized for minimal Cu backgrounds, which limited the conclusions about the symmetry of the Cu debris. The quality of the data limited conclusions on chemical fractionation effects within the burning, expanding, and then cooling plasma.
A technique for shell compression measurements of laser fusion targets by neutron activation of a rubidium tracer
At the Nova Laser, the activation of a rubidium tracer incorporated in the shell of ICF targets has become a standard diagnostic technique for measuring the compressed shell areal density {l angle}{rho}{Delta}R{r angle}. The isotope {sup 85}Rb is activated by 14 MeV implosion neutrons to produce the isomer {sup 84m}Rb(t{sub {1/2}} = 20.5 min) which is used to determine the shell {l angle}{rho}{Delta}R{r angle} while the radioactive isotope {sup 86}Rb(t{sub 1/2} = 18.8 d) is used to determine the fraction of target debris collected as well as to assay the amount of rubidium in the target. The {sup 85}Rb(n,2n){sup 84m}Rb cross-section at 14.1 MeV was measured ({sigma} = 0.514 {plus minus} 0.080 b). Details of the detector system and experimental technique are given. 12 refs., 2 tabs.
Chemical vapour deposition of metal silicides in silicon microelectronics
Abstract As the dimensions of electronic circuits continue to decrease, reaching the submicron size, the importance of metal silicide films is becoming obvious. Among the different techniques which can be used to obtain high quality layers of these materials in a reproducible manner, chemical vapour deposition (CVD) emerges as the most promising solution. In addition to reviewing the various processes, materials and results reported so far on this subject, this paper will focus on the most interesting processes which are the CVD of blanket WSi 2 for gate electrodes and interconnections and of selective TiSi 2 for self-aligned contacts at source and drain levels. In both cases, the authors will endeavour to show that thermodynamic equilibrium calculations in the corresponding systems lead to a better understanding of the as-obtained results and may provide the necessary means for their optimization.