Study of Laser Effects on Heat Shield Materials,
GENERAL ELECTRIC CO PHILADELPHIA PA RE-ENTRY AND ENVIRONMENTAL SYSTEMS DIV
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Materials of the type used for heat shields on re-entry vehicles undergo varying degrees of property and characteristic changes as a result of exposure to laser radiation in a space type environment at flux levels ranging from about 1 wattsq cm up to flux levels in excess of 10,000 wattssq cm. These changes are, in general a outgassing and depolymerization of the resin binder at low heat fluxes with potential loss in strength andor delamination of the shield b surface charring and high rates of outgassing and material decompositionvaporization at intermediate heat fluxes and c excessive rates of outgassing and material vaporization and shield thickness reduction at high heat fluxes. Thus a re-entry vehicle heat shield exposed to laser radiation in a space environment may provide inadequate protection during entry for reasons of reduced structural capability or inadequate remaining shield thickness. Also the heat soak into the shield and structure resulting from exposure times of several minutes may result in unacceptably high levels of temperature for the vehicle substructure or payload prior to or during entry.
- Lasers and Masers