High Energy-intensity Atomic Oxygen Beam Source for Low Earth Orbit Materials Degradation Studies PDF Download
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Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
A high intensity (1019O-atoms/s-sr) high energy (5 eV) source of oxygen atoms has been developed that produces a total fluence of 1022 O-atoms/cm2 in less than 100 hours of continuous operation at a distance of 15 cm from the source. The source employs a CW CO2 laser sustained discharge to form a high temperature (15,000 K) plasma in the throat of a 0.3-mm diameter nozzle using 3--8 atmospheres of rare gas/O2 mixtures. Visible and infrared photon flux levels of 1 watt/cm2 have been measured 15 cm downstream of the source while vacuum UV (VUV) fluxes are comparable to that measured in low earth orbit. The reactions of atomic oxygen with kapton, Teflon, silver, and various coatings have been studied. The oxidation of kapton (reaction efficiency = 3 x 10/sup /minus/24/ cm ± 50%) has an activation energy of 0.8 Kcal/mole over the temperature range of 25/degree/C to 100/degree/C at a beam energy of 1.5 eV and produces low molecular weight gas phase reaction products (H2O, NO, CO2). Teflon reacts with approx.0.1--0.2 efficiency to that of kapton at 25/degree/C and both surfaces show a rug-like texture after exposure to the O-atom beam. Angular scattering distribution measurements of O-atoms show a near cosine distribution from reactive surfaces indicating complete accommodation of the translational energy with the surface while a nonreactive surface (nickel oxide) shows specular-like scattering with 50% accommodation of the translational energy with the surface. A technique for simple on orbit chemical experiments using resistance measurements of coated silver strips is described. 9 figs.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
A high intensity (1019O-atoms/s-sr) high energy (5 eV) source of oxygen atoms has been developed that produces a total fluence of 1022 O-atoms/cm2 in less than 100 hours of continuous operation at a distance of 15 cm from the source. The source employs a CW CO2 laser sustained discharge to form a high temperature (15,000 K) plasma in the throat of a 0.3-mm diameter nozzle using 3--8 atmospheres of rare gas/O2 mixtures. Visible and infrared photon flux levels of 1 watt/cm2 have been measured 15 cm downstream of the source while vacuum UV (VUV) fluxes are comparable to that measured in low earth orbit. The reactions of atomic oxygen with kapton, Teflon, silver, and various coatings have been studied. The oxidation of kapton (reaction efficiency = 3 x 10/sup /minus/24/ cm ± 50%) has an activation energy of 0.8 Kcal/mole over the temperature range of 25/degree/C to 100/degree/C at a beam energy of 1.5 eV and produces low molecular weight gas phase reaction products (H2O, NO, CO2). Teflon reacts with approx.0.1--0.2 efficiency to that of kapton at 25/degree/C and both surfaces show a rug-like texture after exposure to the O-atom beam. Angular scattering distribution measurements of O-atoms show a near cosine distribution from reactive surfaces indicating complete accommodation of the translational energy with the surface while a nonreactive surface (nickel oxide) shows specular-like scattering with 50% accommodation of the translational energy with the surface. A technique for simple on orbit chemical experiments using resistance measurements of coated silver strips is described. 9 figs.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
An atomic oxygen exposure facility has been developed for studies of material degradation. The goal of these studies is to provide design criteria and information for the manufacture of long life (20 to 30 years) construction material for use in low earth orbit. The studies that are being undertaken using the facility will provide (1) absolute reaction cross sections for use in engineering design problems, (2) formulations of reaction mechanisms for use in selection of suitable existing materials and design of new more resistant ones, and (3) calibration of flight hardware (mass spectrometers, etc.) in order to directly relate experiments performed in low earth orbit to ground based investigations. The facility consists of (1) a cw laser sustained discharge source of O-atoms having a variable energy up to 5 eV and an intensity of between 1015−1°sup 17/ O-atoms s−1 cm−2, (2) an atomic beam formation and diagnostics system consisting of various stages of differential pumping, mass spectrometer detector and time-of-flight analysis, (3) a spinning rotor viscometer for absolute O-atom flux measurements, and (4) provision for using the system for calibration of flight instruments. 15 refs., 10 figs.
Author: J. Kleiman Publisher: Springer Science & Business Media ISBN: 940114768X Category : Technology & Engineering Languages : en Pages : 260
Book Description
This publication presents the proceedings of ICPMSE-3, the third international conference on Protection of Materials and Structures from the Low Earth Orbit Space Environment, held in Toronto April 25-26, 1996. The conference was hosted and organized by Integrity Testing Laboratory Inc, (ITL), and held at the University of Toronto's Institute for Aerospace Studies (UTIAS), where ITL is located. Twenty industrial companies, seven wliversities and eight government agencies from Canada, USA, United Kingdom, France, Israel, Russia, Ukraine and the Netherlands were represented by over 55 participants indicating increasing international co-operation in this critical arena of protection of materials in space. Twenty-five speakers, world experts in their fields, delivered talks on a wide variety of topics on various aspects of material protection in space, Representatives from the Canadian, American, European and Israeli space agencies as well as from leading space research laboratories of major aerospace industries gathered at UTIAS to discuss the latest developments in the field of material and structure protection from the harsh space environment, These proceedings are organized into four sections: a) AONOV and Radiation Effects on Materials and Structures in the Leo Space Environment; b) Interaction of Matter with the LEO Environment; c) Large Scale Coating Process Developments for Protection in LEO; d) Synthesis and Modification of Materials and Surfaces for Protection in LEO, This is the third in our on-going series of bi-annual international space materials conferences wllich began in 1992 in Toronto. Jacob Kleiman, Integrity Testing Laboratory Inc.
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Author: Arlene S. Levine
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Author: Los Alamos National Laboratory
Author: J. Kleiman