Study of non-LTE photoionized plasma generated by laser-produced keV blackbody radiator

在天体物理学中，低温气体/等离子体沐浴在强辐射场中，就会遇到光电离等离子体。从双星系统的吸积云，如天鹅座X-3和船帆座X-1，观察到几个keV光谱范围内的x射线线发射，在这些吸积云中，来自致密物体（中子星、黑洞或白矮星）的高强度x射线连续体照射到寒冷和稀薄的云中。x射线连续感应线发射准确地描述了吸积云，但这种光电离等离子体模型的实验验证很少。在这里，我们报告了在实验室中使用高功率激光在良好表征条件下产生的光电离等离子体。用激光内爆的方法产生了一个温度为500 eV的黑体辐射体，对应于一个致密的物体。原子动力学计算暗示了传入的硬x射线直接k壳层光电离的重要性。

Photoionized plasmas are encountered in astrophysics wherever low temperature gas/ plasma is bathed in a strong radiation field. X-ray line emissions in the several keV spectral range were observed from accreting clouds of binary systems, such as CYGNUS X-3 and VELA X-1, in which high-intensity x-ray continua from compact objects(neutron stars, black holes or white dwarfs) irradiate the cold and rarefied clouds. X-ray continuum-induced line emission accurately describes the accreting clouds, but experimental verification of this photoionized plasma model is scarce. Here we report the generation of photoionized plasmas in the laboratory under wellcharacterized conditions using a high-power laser. A blackbody radiator at a temperature of 500 eV, corresponding to a compact object, was created by means of a laser-driven implosion. Atomic kinetic calculations imply the importance of direct K-shell photoionization by incoming hard x-rays.