Dose/Surface Charging and Plasma Monitor (DOS/SCM) Flight Model 2 - HiLET Subsystem Critical Design Review

2004 ◽  
Author(s):  
J. E. Mazur ◽  
W. R. Crain ◽  
C. N. Camacho ◽  
A. Y. Lin ◽  
D. J. Mabry
Author(s):  
P. Alliot ◽  
J.-F. Delange ◽  
V. De Korver ◽  
J.-M. Sannino ◽  
A. Lekeux ◽  
...  

The intent of this publication is to provide an overview of the development of the VINCI® engine over the period 2014–2015. The VINCI® engine is an upper stage, cryogenic expander cycle engine. It combines the required features of this cycle, i. e., high performance chamber cooling and high performance hydrogen turbopump, with proven design concepts based on the accumulated experience from previous European cryogenic engines such as the HM7 and the VULCAIN®. In addition, its high performance and reliability, its restart and throttle capability offer potential applications on various future launcher upper stages as well as orbital spacecraft. At the end of 2014, the VINCI® successfully passed the Critical Design Review that was held after the major subsystem (combustion chamber, fuel and oxygen turbopump) had passed their own Critical Design Review all along the second half of 2014. In December, a Ministerial Conference at government level gave priority to the Ariane 6 program as Europe future launcher. In the framework of this decision, VINCI® was confirmed as the engine to equip Ariane 6 cryogenic upper stage engine. This publication shows how the VINCI development is progressing toward qualification, and also how the requirements of the new Ariane 6 configuration taken into account, i. e., offering new opportunities to the launch system and managing the new constraints. Moreover, the authors capitalize on the development already achieved for the evolution of Ariane 5. In parallel to completing the engine development and qualification, the configuration and the equipment of the propulsive system for Ariane 6 such as the components of the pressurization and helium command systems, board to ground coupling equipment, are being defined.


Author(s):  
Lawrence P. Chao ◽  
Irem Tumer ◽  
Kosuke Ishii

This report describes the state of design reviews observed at NASA and research into improving review practices. There are many types of reviews at NASA. Formal, programmatic project reviews such as the Preliminary Design Review and Critical Design Review are a required part of every project and mission development. However, the informal and technical engineering peer reviews that support teams’ work on such projects are informal, ad hoc, and inconsistent across the organization. The goal of this work is to identify best practices and lessons learned from NASA’s review experience, benchmark against industry techniques, and develop methodologies to improve the process. Thus far, the research has determined that the organization, composition, scope, and execution, including the use of information technology and structured design methodologies, of reviews all impact the technical, engineering peer reviews to help NASA work towards error-proofing the design process.


Author(s):  
T.C. Sheu ◽  
S. Myhajlenko ◽  
D. Davito ◽  
J.L. Edwards ◽  
R. Roedel ◽  
...  

Liquid encapsulated Czochralski (LEC) semi-insulating (SI) GaAs has applications in integrated optics and integrated circuits. Yield and device performance is dependent on the homogeniety of the wafers. Therefore, it is important to characterise the uniformity of the GaAs substrates. In this respect, cathodoluminescence (CL) has been used to detect the presence of crystal defects and growth striations. However, when SI GaAs is examined in a scanning electron microscope (SEM), there will be a tendency for the surface to charge up. The surface charging affects the backscattered and secondary electron (SE) yield. Local variations in the surface charge will give rise to contrast (effectively voltage contrast) in the SE image. This may be associated with non-uniformities in the spatial distribution of resistivity. Wakefield et al have made use of “charging microscopy” to reveal resistivity variations across a SI GaAs wafer. In this work we report on CL imaging, the conditions used to obtain “charged” SE images and some aspects of the contrast behaviour.


Sign in / Sign up

Export Citation Format

Share Document