Impact of forced convective heat transfer on temperature uniformity and frequency doubling efficiency in large aperture ammonium dihydrogen phosphate (ADP) crystals

Abstract

With advancements in optical technology, the large-aperture ADP crystals have grown significantly used in high-power laser systems. Ensuring their optimal performance in such applications necessitates effective control over the temperature uniformity of crystals, this research primarily delves into the influence of forced convective heat transfer on the temperature uniformity of ADP crystals and examines the subsequent effects on the frequency-doubling efficiency of crystals. Thus, this study developed a fan-forced convective heating scheme that was tailored for large-aperture ADP crystals and scrutinized pivotal factors impacting the temperature distribution of the crystal. By integrating numerical simulations with experimental approaches, the flow field and temperature field distribution patterns were discerned at varying fan tilt angles. Additionally, the distribution of the crystal's frequency doubling efficiency was determined. The results showcased that with a fan tilt angle set at 30.0°, the ADP crystal's temperature uniformity achieved a measure of 0.03 °C, and the frequency doubling conversion efficiency peaked at 87.0 %. A reduction in the cavity length to 800 mm further refined the crystal's temperature uniformity, bringing it down to 0.02 °C. This study demonstrated that forced convection can markedly augment the temperature uniformity of the crystal. These insights are invaluable to the domains of optical applications and crystal engineering, paving the way for enhanced performance and application of ADP crystals in controlled nuclear fusion reaction devices.