Thermal aspects of particle engulfment by a solidifying front

The solidification front under pushing conditions as well as the changes in shape that take place during the engulfment process are investigated for polyamide and steel spheres in an ice-water system. The examination of all subsequent stages of trapping make evident that thermal effects are of prime importance in the interface shape, when large spheres (size of the order of some millimeters) are considered.info:eu-repo/semantics/publishe

Experimental characterization of ultraviolet radiation of air in a high enthalpy plasma torch facility

During atmospheric reentry, a plasma is formed ahead of the surface of the vehicle and the excited particle present in the plasma produces radiative heating fluxes to the surface of the vehicle. A high-temperature air plasma torch operating at atmospheric pressure was used to experimentally reproduce atmospheric reentry conditions. A high-resolution and absolute intensity emission spectrum (full width at half maximum (FWHM) = 0.064 nm) was obtained from 200 to 450 nm and then compared with computational results provided by the SPECAIR code [1]. This paper discusses the comparison of the two spectra over this wavelength range in order to confirm the validity of the calculation and provide direction to improve the calculated spectrum

Synchrotron radiation for microstructure fabrication

Most of the presently known microstructures are still fabricated using silicon-based technologies. However, in the case of fabrication using anisotropic etching, geometrical limitations due to the crystallographic nature of silicon prevent the design of any in-place structure shapes. If microsystems, built by means of reactive ion etching and sacrificial layer technology do have freedom for lateral geometry, they are limited to a few micrometers height only. Nevertheless, and in spite of difficulties to always answer the demands in the best way, real microsystems are produced by these techniques and are currently present on the market. To overpass these limitations, other technologies have been studied and developed in recent years. Among them the LIGA process (German acronym for Lithography, Electroplating, Molding), which uses synchrotron radiation and in particular its hard X-Ray spectrum, is certainly the most promising one regarding to, very high aspect ratio, submicron precision, arbitrary pattering and mass production capabilities. Furthermore, LIGA can handle a large variety of materials to fabricate microsystems