Effects of OH and Cl Impurities on the Optical Properties and Radiation Resistance of Silica Glass

ABSTRACT Silica glass plays a significant role in aerospace and laser fusion applications; however, radiation‐induced performance degradation severely limits its service life. This study focused on five types of high‐purity quartz glass: low‐Cl high‐OH (S1), low‐Cl medium‐OH (S2), low‐Cl OH‐free (S3), high‐Cl OH‐free (S4), and Cl‐free OH‐free (7979). All samples underwent prolonged thermal annealing at 1000°C for 20 h to standardize the fictive temperature ( T f ) and evacuate residual hydrogen molecules from the silica glass. This step aimed to eliminate the influence of T f and hydrogen on the optical and radiation‐resistant properties, allowing the study to concentrate on the effects of OH and Cl impurities. The hydrogen molecule content was measured using Raman spectroscopy, and the OH content and T f were determined using Fourier transform infrared spectroscopy. A 6 0 Co gamma‐ray source provided irradiation with a total dose of 100 kGy. Changes in the optical properties before and after irradiation were analyzed using waveguide‐prism coupling instruments, vacuum ultraviolet spectrophotometry, ultraviolet–visible spectrophotometry, and fluorescence spectroscopy. The types of radiation‐induced color center defects were identified using fluorescence spectroscopy and continuous‐wave electron paramagnetic resonance. Radiation‐induced absorption spectra were deconvoluted to determine the evolution of different color center defect concentrations with varying OH and Cl contents. The results indicate that the OH and Cl contents significantly affect the refractive index, ultraviolet (UV) absorption, infrared absorption, and radiation resistance of the quartz glass. Higher Cl content increases the concentrations of radiation‐induced defects (Si–E′, POR, ODC(II)), degrading the radiation resistance of silica glass. Higher OH content suppresses Si–E′, POR, and ODC(II) formation, improving UV radiation resistance, but enhances NBOHC defects, worsening performance at 620 nm.