X-ray standing wave and reflectometric characterization of multilayer structures

Microstructural characterization of synthetic periodic multilayers by x-ray standing waves have been presented. It has been shown that the analysis of multilayers by combined x-ray reflectometry (XRR) and x-ray standing wave (XSW) techniques can overcome the deficiencies of the individual techniques in microstructural analysis. While interface roughnesses are more accurately determined by the XRR technique, layer composition is more accurately determined by the XSW technique where an element is directly identified by its characteristic emission. These aspects have been explained with an example of a 20 period Pt/C multilayer. The composition of the C-layers due to Pt dissolution in the C-layers, Pt$_{x}$C$_{1-x}$, has been determined by the XSW technique. In the XSW analysis when the whole amount of Pt present in the C-layers is assumed to be within the broadened interface, it l eads to larger interface roughness values, inconsistent with those determined by the XRR technique. Constraining the interface roughness values to those determined by the XRR technique, requires an additional amount of dissolved Pt in the C-layers to expl ain the Pt fluorescence yield excited by the standing wave field. This analysis provides the average composition Pt$_{x}$C$_{1-x}$ of the C-layers .Comment: 12 pages RevTex, 10 eps figures embedde

Tritium related safety considerations for mirror upgrades

One of the primary objectives of the MFTF-B upgrades is to demonstrate the technology of tritium breeding in a reactor-like configuration. This requires use and processing of tritium, involving an inventory of several hundred grams at the plant. This paper reviews the results of a preliminary assessment of the radiation hazard associated with the handling of tritium. The radiation dose consequences due to tritium release from normal operation and due to postulated accidents on plant personnel and the public were assessed. Maximum credible (probability < 10/sup -3/, but > 10/sup -7//yr) accidental releases were estimated to be 10 gm in the reactor building and 100 gm in the tritium-processing building. Higher probability (> 10/sup -3//yr) accidents or component failures would result in much smaller releases. In the reactor building, the most severe accident would result from the rupture of a plasma exhaust duct from the end cell or the tritium feed pipe to the neutral beam injector, accompanied by a fire. In the tritium processing building, the most severe accident would be the rupture of the Isotope Separation System (ISS) distillation columns and vacuum jackets accompanied by a fire

Large matrix-vector products on distributed bus networks with communication delays using the divisible load paradigm: Performance analysis and simulation

10.1016/S0378-4754(01)00329-9Mathematics and Computers in Simulation58171-92MCSI

Natural Coke (Jhama), its Properties and Possible Utilization

It has been estimated that about 400 million tones of natural coke (Jhana) exists in the Jharia coalfield. Apart from difficulties of mining this hard material, its utilization is the biggest stumbling block in its winning. The paper makes a study of the different properties of natural coke from different sources of the Jharia coalfield with a view to studying the potentialities of its use. Some of the important observations are – the very low melting point of the ash and very good combustion characteristics when the material is crushed to a particular size. The first property suggests the possibility of its utilization in furnaces where a molten ash is desirable for ease of removal and the second property suggests its possible utilization as a domestic fuel. The formation of the natural coke must have taken place at a temperature of above 600ºC but not exceeding 900ºC. the composition of ash indicates reaction of the intrusive material with coal during the formation of natural coke

Fusion reactor design studies: standard unit costs and cost scaling rules

This report establishes standard unit costs and scaling rules for estimating costs of material, equipment, land, and labor components used in magnetic confinement fusion reactor plant construction and operation. Use of the standard unit costs and scaling rules will add uniformity to cost estimates, and thus allow valid comparison of the economic characteristics of various reactor concepts