Anomalous Stabilization of Hydrodynamic Instability Due to Nonlocal Energy Transport

流体动力不稳定性的抑制对于惯性聚变能源的发展至关重要。在开始这项研究之前，我们发现观测到的瑞利-泰勒不稳定性的增长率比理论预测的要小，并归因于非局域电子能量传输。尽管增长率被抑制本身对激光聚变来说是个好消息，但尚不清楚未来的反应堆等离子体是否会出现同样的影响。本研究的目的是为了更好地了解这一问题的答案。为此，我们进行了以下三个实验。生长速率的抑制在短波长区最为明显。我们应用改进的云纹干涉法，成功地观测到了短波长的不稳定性。增长率与考虑非局域电子输运的预测符合得很好。非局部能源运输的直接证据至关重要。我们发展了X射线半影成像和菲涅耳相位波带板成像，并成功地测量了等离子体密度。观测到的密度分布与非局地输运的预测结果吻合较好。未来反应堆目标的稳定性必须进行测试。我们已经开发了一种新的激光系统，它结合了所有现有的激光光束，以便可以模拟未来目标的一小部分，并测量了Rayleigh-Taylor不稳定性的增长率。我们测量所有必要的量来测试各种Rayleigh-Taylor不稳定性理论的活动正在取得成果。尽管有一些尚未解决的现象，但对烧蚀瑞利-泰勒不稳定性的理解正接近“游戏的结束”，这是四分之一多世纪以来的一个中心问题。

Suppression of hydrodynamic instability is critically important for the development of, inertial fusion energy. Before starting this research project, we found that the observed growth rates of the Rayleigh-Taylor instability were smaller than the theoretical predictions, and attributed to the nonlocal electron energy transport.Although the suppression of the growth rate itself is "good news" for laser fusion, it is unclear whether the same effect will be revealed in future reactor plasmas. The purpose of this research is to obtain good understanding to answer this question.For this purpose, we have performed the following three experiments.1. The suppression of growth rates is most pronounced in the short wavelength region. We have applied the innovated moire interferometry, and succeeded to observe the instability at short wavelengths. The growth rates have agreed well with the prediction that takes into account nonlocal electron transport.2. Direct evidence of nonlocal energy transport is critical. We have developed x-ray penumbral imaging and Fresnel phase zone plate imaging, and succeeded to measure plasma density. The observed density profiles were in better agreement with the prediction of nonlocal transport.3. Stability of targets for future reactors must be tested. We have developed a new laser system that combines all the existing laser beams so that a small portion of future target can be simulated, and measured the growth rates of Rayleigh-Taylor instability.Our activity to measure all necessary quantities to test various Rayleigh-Taylor instability theories are bearing fruit. Although there are some unresolved phenomena, the understanding of the ablative Rayleigh-Taylor instability that have been a central issue in more than a quarter century is approaching to "the end of the game".