Harilal S S, Kautz E J, Bernacki B E, Phillips M C, Skrodzki P J, Burger M, Jovanovic I
Pacific Northwest National Laboratory, Richland, WA 99352, USA.
Department of Nuclear Engineering and Radiological Sciences, University of Michigan, MI 48109, USA and Center for Ultrafast Optical Science, University of Michigan, MI 48109, USA.
Phys Chem Chem Phys. 2019 Aug 7;21(29):16161-16169. doi: 10.1039/c9cp02250c. Epub 2019 Jul 11.
We investigate the oxidation of uranium (U) species, the physical conditions leading to uranium monoxide (UO) formation and the interplay between plume hydrodynamics and plasma chemistry in a laser-produced U plasma. Plasmas are produced by ablation of metallic U using nanosecond laser pulses. An ambient gas environment with varying oxygen partial pressures in 100 Torr inert Ar gas is used for controlling the plasma oxidation chemistry. Optical emission spectroscopic analysis of U atomic and monoxide species shows a reduction in the emission intensity and persistence with increasing oxygen partial pressure. Spectral modelling is used for identifying the physical conditions in the plasma that favor UO formation. The optimal temperature for UO formation is found to be in the temperature range of ∼1500-5000 K. The spectrally integrated and spectrally filtered (monochromatic) imaging of U atomic and molecular species reveals the evolutionary paths of various species in the plasma. Our results also highlight that oxidation in U plasmas predominantly occurs at the cooler periphery and is delayed with respect to plasma formation, and the dissipation of molecular species strongly depends on oxygen partial pressure.
我们研究了铀（U）物种的氧化、导致一氧化铀（UO）形成的物理条件以及激光产生的铀等离子体中羽流流体动力学与等离子体化学之间的相互作用。等离子体通过使用纳秒激光脉冲烧蚀金属铀产生。在100托惰性氩气中具有不同氧分压的环境气体环境用于控制等离子体氧化化学。对U原子和一氧化物物种的光学发射光谱分析表明，随着氧分压的增加，发射强度和持续时间会降低。光谱建模用于确定等离子体中有利于UO形成的物理条件。发现UO形成的最佳温度在约1500 - 5000 K的温度范围内。U原子和分子物种的光谱积分和光谱滤波（单色）成像揭示了等离子体中各种物种的演化路径。我们的结果还突出表明，铀等离子体中的氧化主要发生在较冷的外围，并且相对于等离子体形成有所延迟，分子物种的消散强烈依赖于氧分压。
