Bremsstrahlung emission profile from intense laser-solid interactions as a function of laser focal spot size
Bremsstrahlung emission profile from intense laser-solid interactions as a function of laser focal spot size
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DOI：
10.1088/1361-6587/aaf596
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发表时间：
2019-03-01
影响因子：
2.2
通讯作者：
Neely, D.
中科院分区：
文献类型：
--
作者：
Armstrong, C. D.;Brenner, C. M.;Neely, D.
高强度激光与固体相互作用产生的韧致辐射x射线发射轮廓为研究固体内部快电子输运提供了有价值的信息。使用半影成像，我们通过逐渐增加目标上的激光焦斑尺寸来将该韧致辐射源的空间轮廓作为激光强度的函数。实验数据显示了双源结构;一个来自电子的中央通道，第二个来自再循环电子电流的较大衬底源。结果表明，在两个X射线源之间的强度对比度的一个数量级的改善是实现与一个大的焦斑，指示在射线照相中的应用的优选条件。一个分析模型推导出描述的超热电子人口，有助于基板和中央通道源通过一个目标的运输。该模型是在良好的协议与这里提出的实验结果，并进一步应用于预测激光强度，以实现最佳的空间对比度为各种目标材料和厚度。
The bremsstrahlung x-ray emission profile from high intensity laser-solid interactions provides valuable insight to the internal fast electron transport. Using penumbral imaging, we characterise the spatial profile of this bremsstrahlung source as a function of laser intensity by incrementally increasing the laser focal spot size on target. The experimental data shows a dual-source structure; one from the central channel of electrons, the second a larger substrate source from the recirculating electron current. The results demonstrate than an order of magnitude improvement in the intensity contrast between the two x-ray sources is achieved with a large focal spot, indicating preferable conditions for applications in radiography. An analytical model is derived to describe the transport of suprathermal electron populations that contribute to substrate and central channel sources through a target. The model is in good agreement with the experimental results presented here and furthermore is applied to predict laser intensities for achieving optimum spatial contrast for a variety of target materials and thicknesses.