Properties of a-C:H Coatings Prepared by PECVD for Laser Fusion Targets

Abstract Amorphous hydrogenated carbon films are the nominal ablators to be used in French inertial confinement fusion (ICF) experiments. These targets are developed for the future Megajoule laser (LMJ) of the CEA. Coatings are prepared by remote rf-PECVD and their properties have been investigated. Laser fusion targets must have optimized optical characteristics (UV-visible transparency), mechanical strength, high gas permeability, low oxygen pollution. The films are characterized by 13C NMR, RBS, UV-visible spectroscopy, gas permeation, thermogravimetric analysis. A study of the glow discharge is also developed using optical emission spectroscopy and mass spectrometry. In this article, we try to understand the relationships between precursors, plasma composition, deposition rate and film properties. Best results are obtained with trans-2-butene/hydrogen (T2B/H2) coatings in post-discharge.

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