Experimental characterization of hot-electron emission and shock dynamics in the context of the shock ignition approach to inertial confinement fusion
Experimental characterization of hot-electron emission and shock dynamics in the context of the shock ignition approach to inertial confinement fusion
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DOI：
10.1063/5.0059651
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发表时间：
2021-10-01
影响因子：
2.2
通讯作者：
Batani, D.
中科院分区：
文献类型：
--
作者：
Tentori, A.;Colaitis, A.;Batani, D.
我们报告的背景下，冲击点火（SI）的惯性约束聚变的方法进行的OMEGA-EP激光设备上的平面靶实验。该实验旨在表征强冲击在物质中的传播和热电子（HEs）的产生，激光参数与SI（1-ns紫外激光束，I类似于10（16）W/cm（2））有关。为了研究流体动力学演化，对传播的激波阵面进行了时间分辨射线照相。热电子源的特点是在麦克斯韦温度，T-h，和激光热电子能量转换效率？使用来自不同X射线光谱仪的数据。这些数据的后处理给出了T-h和？[i.e., T h [ keV ]（sic）（20，50）和？(sic)（百分之二，百分之十三）]。这些值用作流体动力学模拟的输入，以重现射线照片中获得的结果，从而限制HE测量的范围。根据这个过程，我们发现激光器将大约10%+/-4%的能量转换成T_h = 27 +/-8 keV的超热电子。本文展示了如何耦合不同的诊断和数值工具，需要充分约束的问题，解决大的模糊性来自光谱仪数据的后处理。然后讨论了热电子对激波动力学的影响，表明激波前缘周围的压力增加。在没有预压缩激光脉冲的情况下，在该实验中发现的低温对于SI方案可能是有利的，但是高转换效率可能导致壳层厚度的增加，对内爆具有不利影响。
We report on planar target experiments conducted on the OMEGA-EP laser facility performed in the context of the shock ignition (SI) approach to inertial confinement fusion. The experiment aimed at characterizing the propagation of strong shock in matter and the generation of hot electrons (HEs), with laser parameters relevant to SI (1-ns UV laser beams with Isimilar to10(16) W/cm(2)). Time-resolved radiographs of the propagating shock front were performed in order to study the hydrodynamic evolution. The hot-electron source was characterized in terms of Maxwellian temperature, T-h, and laser to hot-electron energy conversion efficiency?using data from different x-ray spectrometers. The post-processing of these data gives a range of the possible values for T-h and?[i.e., T h [ keV ] (sic)& nbsp;(20, 50) and?(sic)& nbsp; (2%, 13%)]. These values are used as input in hydrodynamic simulations to reproduce the results obtained in radiographs, thus constraining the range for the HE measurements. According to this procedure, we found that the laser convertssimilar to10% +/-& nbsp;4% of energy into hot electrons with T-h = 27 +/-& nbsp;8 keV. The paper shows how the coupling of different diagnostics and numerical tools is required to sufficiently constrain the problem, solving the large ambiguity coming from the post-processing of spectrometers data. The effect of the hot electrons on the shock dynamics is then discussed, showing an increase in the pressure around the shock front. The low temperature found in this experiment without pre-compression laser pulses could be advantageous for the SI scheme, but the high conversion efficiency may lead to an increase in the shell adiabat, with detrimental effects on the implosion.