Polyimide (PI, Kapton-H®) films are widely utilized in the spacecraft industry for their insulating properties, mechanical durability, light weight, and chemical resistance to radiation. Still PI materials remain exposed to a combination of high-energy electrons, protons, and ultraviolet (UV) photons, particles primarily responsible for radiation-induced damage in geosynchronous Earth orbit (GEO), which drastically change PI’s properties. This work reviews the effect of electron, proton, and UV photon irradiation on the material properties (morphology, absorption, mechanical properties, and charge transport) of PI. The different damaging mechanisms and chemical consequences that drive changes in the material properties of PI caused by each individual kind of irradiation will be discussed in detail.
Generation of programmable near-Fourier-transform-limited pulses of narrow-band laser radiation from the near infrared to the vacuum ultraviolet Rev. Sci. Instrum. 76, 103103 (2005) Nanosecond optical pulses with high power and spectral brightness in the deep ultraviolet ͑UV͒ region have been produced by sum frequency mixing of nearly transform-limited-bandwidth IR light originating from a home-built injection-seeded ring cavity KTiOPO 4 optical parametric oscillator ͑OPO͒ and the fourth harmonic beam of an injection-seeded Nd:YAG laser used simultaneously to pump the OPO with the second harmonic. We demonstrate UV output, tunable from 204 to 207 nm, which exhibits pulse energies up to 5 mJ with a bandwidth better than 0.01 cm −1 . We describe how the approach shown in this paper can be extended to wavelengths shorter than 185 nm. The injection-seeded OPO provides high conversion efficiency ͑Ͼ40% overall energy conversion͒ and superior beam quality required for highly efficient downstream mixing where sum frequencies are generated in the UV. The frequency stability of the system is excellent, making it highly suitable for optical pumping. We demonstrate high resolution spectroscopy as well as optical pumping using laser-induced fluorescence and stimulated emission pumping, respectively, in supersonic pulsed molecular beams of nitric oxide.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.