IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Applied Surface Analysis Thursday Sessions
       Session AS-ThM

Paper AS-ThM3
Atomic Oxygen Irradiation of Polymers: Ground Simulation of LEO Environment

Thursday, November 1, 2001, 9:00 am, Room 134

Session: Oxides and Oxidation
Presenter: G. Lempert, Soreq NRC, Israel
Authors: G. Lempert, Soreq NRC, Israel
R. Intrater, Soreq NRC, Israel
I. Gouzman, Soreq NRC, Israel
E. Grossman, Soreq NRC, Israel
Y. Lifshitz, Soreq NRC, Israel
A. Hoffman, Technion Haifa, Israel
Correspondent: Click to Email
External surfaces of spacecraft in low earth orbit (LEO) are exposed to the various constituents of the space environment, including atomic oxygen (AO) and solar UV radiation, which often compromise the material properties. Material degradation by LEO atomic oxygen is simulated in a variety of experimental facilities, each with their respective limitations. RF oxygen plasma is a widely used facility for screening materials for LEO application. In addition to the neutral oxygen atoms, the plasma generates electrons and ions as well as vacuum ultraviolet (VUV) radiation, which may also contribute, either directly or synergistically, to degradation of materials. In the present study, direct and synergistic degradation effects on polymers were investigated by exposing the polymers to various combinations of the different species and the VUV emanating from an RF oxygen plasma. The different exposure conditions, including AO alone, AO+VUV, AO+e@super -@+O@super +@+VUV, AO+e@super -@+VUV, AO+O@super +@+VUV, were separated downstream beyond the RF reactor exit. The samples were characterized by mass loss measurements, changes in surface composition, by XPS, and ATR-FTIR spectroscopy, and changes in surface morphology by AFM. The polymer samples investigated were, Kapton, fluorocarbons such as Teflon FEP, Tefzel and Tedlar, having different C/F ratios, and polyethylene. Fluorine containing polymers were confirmed to be more resistant to AO alone than hydrocarbons. However, fluorocarbon polymers, sensitive to VUV radiation, showed synergistic degradation effects and higher erosion yield under AO+VUV irradiations. The effect may be interpreted by VUV radiation induced scissioning, thereby facilitating the material erosion under AO attack. The results presented demonstrate the synergistic effects on the degradation of different polymer materials and elucidate the limitations of the validity of the common RF plasma for screening materials for LEO applications.