FORMING ADHERENT COATINGS USING PLASMA PROCESSING

Process for forming abherent coatings using plasma processing. Plasma Immersion Ion Processing (PIIP) is a process where energetic (hundreds of eV to many tens of keV) metallic and metalloid ions derived from high-vapor-pressure organometallic compounds in a plasma environment are employed to desposit coatings on suitable substrates, which coatings are subsequently relieved of stress using inert ion bombardment, also in a plasma environment, producing thereby strongly adherent coatings having chosen composition, thickness and density. Four processes are utilized: sputter-cleaning, ion implantation, material deposition, and coating stress relief. Targets are placed directly in a plasma and pulse biased to generate a non-line-of-sight deposition without the need for complex fixturing. If the bias is a relatively high negative potential (20 kV-100 kV) ion implantation will result. At lower voltages (50 V-10 kV), deposition occurs, and the extent of the surface modification can routinely be extended between 1 um and 10 um. By combining plasma based implantation and film deposition, coatings with greatly reduced stress are possible, allowing the ultimate coating thickness to be expanded to tens of microns

Design and Construction Solutions in the Accurate Realization of NCSX Magnetic Fields

The National Compact Stellarator Experiment, NCSX, is being constructed at the Princeton Plasma Physics Laboratory (PPPL) in partnership with the Oak Ridge national Laboratory. The goal of NCSX is to provide the understanding necessary to develop an attractive, disruption free, steady state compact stellaratorbased reactor design. This paper describes the recently revised designs of the critical interfaces between the modular coils, the construction solutions developed to meet assembly tolerances, and the recently revised trim coil system that provides the required compensation to correct for the “as built” conditions and to allow flexibility in the disposition of as-built conditions. In May, 2008, the sponsor decided to terminate the NCSX project due to growth in the project’s cost and schedule estimates. However significant technical challenges in design and construction were overcome, greatly reducing the risk in the remaining work to complete the project

Combination of the W boson polarization measurements in top quark decays using ATLAS and CMS data at s = 8 TeV

Abstract: The combination of measurements of the W boson polarization in top quark decays performed by the ATLAS and CMS collaborations is presented. The measurements are based on proton-proton collision data produced at the LHC at a centre-of-mass energy of 8 TeV, and corresponding to an integrated luminosity of about 20 fb−1 for each experiment. The measurements used events containing one lepton and having different jet multiplicities in the final state. The results are quoted as fractions of W bosons with longitudinal (F0), left-handed (FL), or right-handed (FR) polarizations. The resulting combined measurements of the polarization fractions are F0 = 0.693 ± 0.014 and FL = 0.315 ± 0.011. The fraction FR is calculated from the unitarity constraint to be FR = −0.008 ± 0.007. These results are in agreement with the standard model predictions at next-to-next-to-leading order in perturbative quantum chromodynamics and represent an improvement in precision of 25 (29)% for F0 (FL) with respect to the most precise single measurement. A limit on anomalous right-handed vector (VR), and left- and right-handed tensor (gL, gR) tWb couplings is set while fixing all others to their standard model values. The allowed regions are [−0.11, 0.16] for VR, [−0.08, 0.05] for gL, and [−0.04, 0.02] for gR, at 95% confidence level. Limits on the corresponding Wilson coefficients are also derived

FORMING ADHERENT COATINGS USING PLASMA PROCESSING

Process for forming abherent coatings using plasma processing. Plasma Immersion Ion Processing (PIIP) is a process where energetic (hundreds of eV to many tens of keV) metallic and metalloid ions derived from high-vapor-pressure organometallic compounds in a plasma environment are employed to desposit coatings on suitable substrates, which coatings are subsequently relieved of stress using inert ion bombardment, also in a plasma environment, producing thereby strongly adherent coatings having chosen composition, thickness and density. Four processes are utilized: sputter-cleaning, ion implantation, material deposition, and coating stress relief. Targets are placed directly in a plasma and pulse biased to generate a non-line-of-sight deposition without the need for complex fixturing. If the bias is a relatively high negative potential (20 kV-100 kV) ion implantation will result. At lower voltages (50 V-10 kV), deposition occurs, and the extent of the surface modification can routinely be extended between 1 um and 10 um. By combining plasma based implantation and film deposition, coatings with greatly reduced stress are possible, allowing the ultimate coating thickness to be expanded to tens of microns

Postmortem Cost and Schedule Analysis - Lessons Learned On NCSX

The National Compact Stellarator Experiment (NCSX) was designed to test physics principles of an innovative fusion energy confinement device developed by the Princeton Plasma Physics Laboratory (PPPL) and Oak Ridge National Laboratory (ORNL) under contract from the US Department of Energy. The project was technically very challenging, primarily due to the complex component geometries and tight tolerances that were required. As the project matured these challenges manifested themselves in significant cost overruns through all phases of the project (i.e. design, R&D, fabrication and assembly). The project was subsequently cancelled by the DOE in 2008. Although the project was not completed, several major work packages, comprising about 65% of the total estimated cost (excluding management and contingency), were completed, providing a data base of actual costs that can be analyzed to understand cost drivers. Technical factors that drove costs included the complex geometry, tight tolerances, material requirements, and performance requirements. Management factors included imposed annual funding constraints that throttled project cash flow, staff availability, and inadequate R&D. Understanding how requirements and design decisions drove cost through this top-down forensic cost analysis could provide valuable insight into the configuration and design of future state-of-the art machines and other devices