大能量钕玻璃棒状激光器新型热管理技术

Novel heat-management technology for high enegy pulsed Nd:glass rod laser

针对kJ级大能量钕玻璃固体脉冲激光器,对比研究了传统恒温水冷方式和采用加热控制的新型热管理技术下的激光棒温度分布情况。结果表明,采用新型热管理技术可大大降低棒内温度梯度,减小泵浦过程中的热效应,确保大能量激光输出;而且加热循环水的最佳升温值在单泵浦脉冲引起的激光棒平均温升值附近,使得径向温差最小,该最佳升温值与脉冲间隔时间有关,比如脉冲间隔15 s时,循环水在每个脉冲过后的最佳升温值为单泵浦脉冲引起的激光棒平均温升值的0.85倍;采用加热控制后水温和激光棒温度整体升高,因此在工作一个脉冲串后,必须恢复激光棒温度到初始状态,然后再进行下一个脉冲串工作。

For a pulsed kJ-level high energy Nd：glass solid-state laser, temperature distributions have been numerically studied under two thermal management methods, a traditional method with a fixed cooling water temperature, and a novel method with a prompt water temperature rise after each pump pulse. The results have shown that the temperature gradient in the laser rod can be limited to a low level to ensure the high energy output laser with a high beam quality, by employing the novel thermal management method. And the optimized values of the heated water temperature rise, near the average temperature rise value caused by one pump pulse, have been calculated for different pulse intervals and different input energies. For an interval time of 15 s, the heated water temperature rise after one pumping pulse is optimized to be 0.85 times that of the average temperature rise resulted from one pumping pulse. As the temperature will become higher and higher under the novel method, a process of forced cooling is necessary to recover the water and rod to initial state after a series of pulses.