Study of organic contamination induced by outgassing materials. Application to the Laser MégaJoule optics

Abstract

International audienceOrganic contamination may decrease the targeted performances of coated surfaces. To study the contamination induced by surrounding materials, a method using a thermal extractor is presented in the first part of this work. Besides its normal operation (analyses of outgassing compounds from a material), this device is used in an original way to contaminate and decontaminate samples. Efficiency of contamination and decontamination protocols are assessed by automated thermal desorption and gas chromatography coupled with mass spectrometry and by secondary ion mass spectrometry coupled with a time of flight mass analyzer. This enables to study the contamination induced by a bulk material outgassing and to take in consideration the possible competition between outgassed species. This method is then applied to investigate contamination of Laser MégaJoule sol–gel coated optics by a retractable sheath. The impact of the temperature on the outgassing of the sheath has been highlighted. Increasing temperature from 30 to 50 • C enables the outgassing of organophosphorous compounds and increases the outgassing of oxy-genated compounds and phthalates. Chemical analyses of contaminated optics have highlighted affinities between the sol–gel coating and phthalates and organophosphorous, and low affinities with aromatics and terpens. Finally, samples with increasing levels of contamination have been realized. However a saturation phenomenon is observed at 90 ng cm–2

Analysis of laser-induced contamination at 515 nm in the sub-ps/MHz regime

“…Other studies were also conducted in the context of high power laser facilities for fusion experiments, also dealing with molecular contamination under exposure to nanosecond UV lasers. [35][36][37][38] In that case, the repetition rate is very low and the number of laser shots is very limited. Ex situ diagnostics such as Nomarski Microscopy, Confocal Fluorescence Microscopy (CLSM), White Light Interferometry (WLIM), Atomic Force Microscopy (AFM) are the most relevant tools of investigation.…”

Laser-Induced Thermal Damage Simulations of Optical Coatings Due to Intercoupling of Defect and Organic Contamination

“…Organic outgassing contaminants in closed vacuum environments have suspected to be a critical factor for laser induced damage degradation behaviors [4]- [6]. The damaged degradation mechanisms, such as photoinduced chemical damage, thermo-mechanical damage, micro-lensing effect mechanism and so on [7]- [9], have been proposed to explain the corresponding damaged behavior. However, for the nanosecond laser pulses, laser-induced damage of optical films is defect-related damage, and the number of the sensitive defects determines the damage probability and the LIDT of the samples.…”

Airborne molecular contamination: quality criterion for laser and optical components

“…22 Generally only organic compounds and condensables are of interest because other AMCs are usually not observed. Volatile organic compounds are known to be emitted from various materials like plastics, sealants, paints, flooring materials.…”