Ultrafast dynamics of a near-solid-density layer in an intense femtosecond laser-excited plasma
Ultrafast dynamics of a near-solid-density layer in an intense femtosecond laser-excited plasma
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DOI：
10.1063/1.4882675
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发表时间：
2014-06
影响因子：
2.2
通讯作者：
A. Adak;D. Blackman;G. Chatterjee;P. Singh;A. D. Lad;P. Brijesh;A. Robinson;J. Pasley;G. Kumar
中科院分区：
文献类型：
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作者：
A. Adak;D. Blackman;G. Chatterjee;P. Singh;A. D. Lad;P. Brijesh;A. Robinson;J. Pasley;G. Kumar
本文报道了利用时间分辨泵浦-探测多普勒光谱法研究飞秒强红外（λ = 800 nm）激光产生的近固体密度等离子体的皮秒动力学。在反射的三次谐波（λ = 266 nm）探测脉冲中观察到初始的红移，其在较长的探测延迟下得到蓝移。粒子在细胞和辐射流体动力学建模的组合进行模拟泵浦激光与固体目标的相互作用。对结果进行后处理以预测多普勒频移。一个很好的协议之间发现这样的建模和实验的结果。该模型表明，在实验中观察到的临界表面的初始向内运动是由于一个冲击波般的扰动，发射的泵相互作用，传播到目标的通道。此外，为了达到最好的实验数据拟合，它是必要的，以纳入批量离子加速的影响所产生的静电场的驱逐电子从激光包络。我们还提出了时间分辨泵浦-探测反射法的结果，这是证实了光谱结果使用1-D反射率模型。
We report on the picosecond dynamics of a near-solid-density plasma generated by an intense, infrared (λ = 800 nm) femtosecond laser using time-resolved pump-probe Doppler spectrometry. An initial red-shift is observed in the reflected third harmonic (λ = 266 nm) probe pulse, which gets blue-shifted at longer probe-delays. A combination of particle-in-cell and radiation-hydrodynamics modelling is performed to model the pump laser interaction with the solid target. The results are post-processed to predict the Doppler shift. An excellent agreement is found between the results of such modelling and the experiment. The modelling suggests that the initial inward motion of the critical surface observed in the experiment is due to the passage of a shock-wave-like disturbance, launched by the pump interaction, propagating into the target. Furthermore, in order to achieve the best possible fit to the experimental data, it was necessary to incorporate the effects of bulk ion-acceleration resulting from the electrostatic field set up by the expulsion of electrons from the laser envelope. We also present results of time-resolved pump-probe reflectometry, which are corroborated with the spectrometry results using a 1-D reflectivity model.