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The organic contamination damage of large-aperture optical components limits laser energy improvement of inertial confinement fusion (ICF). In situ cleaning of large-aperture optical components via low-pressure plasma is foreseen to remove organic contaminants on the optical surface. Herein, the low-pressure plasma equipment was proposed and conducted on surfaces of SiO2 sol-gel antireflection films in situ by experiments. Its electrical discharge parameters were investigated and optimized during plasma cleaning. Plasma diffusion characteristics and homogeneity in large-aperture windows were analyzed by optical emission spectroscopy. A dramatic degradation in the optical properties of components could be observed after organic contamination for 5 hours. Transmittance, laser-induced damage threshold, and surface morphology observation results demonstrated that low-pressure air plasma removed the organic contaminants on the surface of sol-gel antireflection films without damage and metal contamination. After plasma cleaning, the hydrophilicity of films increased significantly due to the increase in polar components of surface free energy. The mechanism of plasma cleaning organic contaminants was confirmed from X-ray photoelectron spectroscopy measurements. These salient results provide a new alternative method for removing organic contaminants in situ on large-aperture optical components and a foundation for improving the energy output of the ICF system.

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