High energy-intensity atomic oxygen beam source for low earth orbit materials degradation studies
A high intensity (10/sup 19/O-atoms/s-sr) high energy (5 eV) source of oxygen atoms has been developed that produces a total fluence of 10/sup 22/ O-atoms/cm/sup 2/ in less than 100 hours of continuous operation at a distance of 15 cm from the source. The source employs a CW CO/sub 2/ 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/O/sub 2/ mixtures. Visible and infrared photon flux levels of 1 watt/cm/sup 2/ 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 /times/ 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 (H/sub 2/O, NO, CO/sub 2/). 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.
- Research Organization:
- Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 7137581
- Report Number(s):
- LA-UR-88-2188; CONF-880781-1; ON: DE88014316
- Resource Relation:
- Conference: 16. international symposium on rarefied gas dynamics, Pasadena, CA, USA, 11 Jul 1988; Other Information: Portions of this document are illegible in microfiche products
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
42 ENGINEERING
OXYGEN
ATOMIC BEAM SOURCES
SURFACE COATING
MATERIALS TESTING
ANGULAR DISTRIBUTION
CARBON DIOXIDE LASERS
ENERGY TRANSFER
OXYGEN 16 BEAMS
REENTRY VEHICLES
SILVER
TEFLON
BEAMS
DEPOSITION
DISTRIBUTION
ELEMENTS
FLUORINATED ALIPHATIC HYDROCARBONS
GAS LASERS
HALOGENATED ALIPHATIC HYDROCARBONS
ION BEAMS
LASERS
MATERIALS
METALS
NEUTRAL BEAM SOURCES
NONMETALS
ORGANIC COMPOUNDS
ORGANIC FLUORINE COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC POLYMERS
PETROCHEMICALS
PETROLEUM PRODUCTS
PLASTICS
POLYETHYLENES
POLYMERS
POLYOLEFINS
POLYTETRAFLUOROETHYLENE
SPACE VEHICLES
SYNTHETIC MATERIALS
TESTING
TRANSITION ELEMENTS
VEHICLES
640301* - Atomic
Molecular & Chemical Physics- Beams & their Reactions
420500 - Engineering- Materials Testing