Broege Douglas, Spilatro Michael, Duchateau Guillaume, Dorrer Christophe, Demos Stavros G
Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, NY, 14623-1299, USA.
CEA-CESTA, 15 Avenue Des Sablières, CS60001, 33116, Le Barp Cedex, France.
Sci Rep. 2024 Mar 4;14(1):5361. doi: 10.1038/s41598-024-55732-z.
The laser-damage performance characteristics of potassium dihydrogen phosphate (KDP) samples under exposure to a distinctive broadband incoherent laser pulse are investigated. A laser system providing such pulses is intended to explore improved energy-coupling efficiency on the target in direct-drive inertial confinement fusion experiments and provides incoherent bandwidths as large as 10 THz in a nanosecond pulse. A consequence of this bandwidth is very rapid fluctuations in intensity capable of reaching maxima much larger than the average intensity within the pulse. A custom damage-test station has been built to perform measurements with broadband incoherent pulses in order to determine what effect these fast and high-intensity oscillations have on laser damage. A set of experiments under different bandwidth and beam configurations shows the effect to be minimal when probing bulk damage in KDP. Modeling indicates this behavior is supported by long electron-relaxation times compared to the source-field fluctuations, following excitation of individual electrons in the conduction band. The results help better understand the laser-induced-damage mechanisms in KDP, and its ability to operate in broadband temporally incoherent high-energy lasers that may be particularly suitable for future laser-fusion energy systems.
研究了磷酸二氢钾（KDP）样品在受到独特的宽带非相干激光脉冲照射下的激光损伤性能特征。提供此类脉冲的激光系统旨在探索直接驱动惯性约束聚变实验中目标上改进的能量耦合效率，并在纳秒脉冲中提供高达10太赫兹的非相干带宽。这种带宽的一个结果是强度的非常快速的波动，其最大值能够比脉冲内的平均强度大得多。已建立了一个定制的损伤测试站，以使用宽带非相干脉冲进行测量，以确定这些快速和高强度振荡对激光损伤有何影响。在不同带宽和光束配置下进行的一组实验表明，在探测KDP中的体损伤时，这种影响最小。建模表明，与导带中单个电子的激发后源场波动相比，长电子弛豫时间支持了这种行为。这些结果有助于更好地理解KDP中的激光诱导损伤机制，以及其在宽带时间非相干高能激光器中运行的能力，这些激光器可能特别适用于未来的激光聚变能源系统。
