Atomic modeling of photoionization fronts in nitrogen gas
Atomic modeling of photoionization fronts in nitrogen gas
复制标题
氮气中光电离前沿的原子模拟
作者：
W. Gray;P. Keiter;P. Keiter;H. LeFevre;C. R. Patterson;J. S. Davis;K. Powell;C. Kuranz;R. P. Drake
光电离锋在许多天体物理环境中起着主导作用，但在实验室实验中仍然很难实现。最近的论文表明，实验中使用的氮介质保持在10个大气压的压力下，由辐射温度为T $_{\rm R}\sim $100 eV的源照射可以产生可行的光电离前沿。我们提出了一套一维的数值模拟使用\helios\多材料辐射流体动力学代码，模拟这些条件和光电离前沿的形成。我们研究了不同的原子动力学和辐射传输模型对氮气的流体力学和电离状态的影响，发现更复杂的物理，特别是多角度长特征辐射传输模型和碰撞辐射原子模型，显着改变了气体的原子动力学演化。通过计算光电离率、电子碰撞电离率和总复合率之间的比率来确定光电离前沿。我们发现，由于使用更先进的物理发现，光电离前沿很可能在我们的名义模型中形成的电子温度增加。我们报告几个参数的研究结果。在其中一个中，氮气压力固定在10个大气压并改变源辐射温度，而另一个将温度固定在100 eV并改变氮气压力。较低的氮气压力增加了产生光电离前沿的可能性，而改变峰值源温度几乎没有影响。
Photoionization fronts play a dominant role in many astrophysical environments, but remain difficult to achieve in a laboratory experiment. Recent papers have suggested that experiments using a nitrogen medium held at ten atmospheres of pressure that is irradiated by a source with a radiation temperature of T$_{\rm R}\sim$ 100 eV can produce viable photoionization fronts. We present a suite of one-dimensional numerical simulations using the \helios\ multi-material radiation hydrodynamics code that models these conditions and the formation of a photoionization front. We study the effects of varying the atomic kinetics and radiative transfer model on the hydrodynamics and ionization state of the nitrogen gas, finding that more sophisticated physics, in particular a multi-angle long characteristic radiative transfer model and a collisional-radiative atomics model, dramatically changes the atomic kinetic evolution of the gas. A photoionization front is identified by computing the ratios between the photoionization rate, the electron impact ionization rate, and the total recombination rate. We find that due to the increased electron temperatures found using more advanced physics that photoionization fronts are likely to form in our nominal model. We report results of several parameter studies. In one of these, the nitrogen pressure is fixed at ten atmospheres and varies the source radiation temperature while another fixes the temperature at 100 eV and varied the nitrogen pressure. Lower nitrogen pressures increase the likelihood of generating a photoionization front while varying the peak source temperature has little effect.
DOI：
10.3847/1538-4365/aad3c5
发表时间：
2018
期刊：
The Astrophysical Journal Supplement Series
影响因子：
--
作者：
Nikolić, D.;Gorczyca, T. W.;Korista, K. T.;Chatzikos, M.;Ferland, G. J.;Guzmán, F.;van Hoof, P A.;Williams, R. J.;Badnell, N. R.
通讯作者：
Badnell, N. R.
通过 H ii 区域的红外弧探测星风气泡
影响因子：
6.5
作者：
Mackey J
通讯作者：
Mackey J