Experimental study on the melting behavior of clear ice at different temperature gradients under vertical CO₂ laser irradiation

Laser technology provides a promising solution for polar icebreaking due to its quick response, precise targeting, and contactless operation. To assess its suitability for icebreaking in different polar low-temperature environments, a CO₂ laser irradiation experimental system was constructed. The dynamic melting behavior of clear ice at temperature gradients from 0 °C to 40 °C was investigated at a fixed laser power. Research results indicate that the melting process can be divided into three stages based on whether the depth-to-width ratio of the melting hole reaches 1 and whether the average melting length starts to decrease. These stages are the explosion hole-forming stage, radial hole-expanding stage, and rapid hole-deepening stage. As the ice temperature gradient increased, the average axial melting rate showed a nonlinear decreasing trend. From 0 °C to 40 °C, the maximum instantaneous melting rate and average melting rate decreased by 13.7% and 49.7%, respectively. Energy efficiency also declined nonlinearly with higher temperature gradients. At 0 °C and 40 °C, energy efficiencies were 65.99% and 47.51%, respectively. These findings are valuable meaningful for designing and improving laser deicing systems.