Avalanche Photon Cooling by Induced Compton Scattering: Higher-Order Kompaneets Equation
Avalanche Photon Cooling by Induced Compton Scattering: Higher-Order Kompaneets Equation
复制标题
DOI：
10.1093/ptep/ptv086
复制
发表时间：
2015-05
期刊：
影响因子：
--
通讯作者：
S. Tanaka;K. Asano;T. Terasawa
中科院分区：
文献类型：
--
作者：
S. Tanaka;K. Asano;T. Terasawa
感应康普顿散射(ICS)是强电磁辐射与等离子体之间的一种相互作用，它将光子的能量传递给等离子体。尽管ICS对于实验室实验中的激光等离子体相互作用和脉冲星在脉冲星风等离子体中传播的射电辐射是重要的，但光子冷却过程的细节还不清楚。问题是，当ICS占主导地位时，光子谱的演化被描述为一个非线性对流方程，这使得光子谱具有多值性。在这里，我们提出了一种新的方法来处理受ICS影响的光子谱的演化。从高阶Kompaneets方程出发，我们找到了一个解决光子光谱非物理行为的新方程。此外，我们还求出了系统的稳态解析解，它是线性稳定的。在没有人工粘性的情况下，我们成功地模拟了光子光谱的演化。我们发现，随着光子在频率-空间中不断地形成孤立结构，光子在ICS中迅速失去能量。孤立结构具有由电子温度表征的对数相同的宽度。从光子到等离子体的能量转移对于更宽的光子谱更有效，就像在天体物理情况下预期的那样。
Induced Compton scattering (ICS) is an interaction between intense electro-magnetic radiations and plasmas, where ICS transfers the energy from photons to plasmas. Although ICS is important for laser plasma interactions in laboratory experiments and for radio emission from pulsars propagating in pulsar wind plasmas, the detail of photon cooling process has not been understood. The problem is that, when ICS dominates, evolution of photon spectra is described as a nonlinear convection equation, which makes photon spectra to be multi-valued. Here, we propose a new approach to treat evolution of photon spectra affected by ICS. Starting from the higher-order Kompaneets equation, we find a new equation that resolves the unphysical behavior of photon spectra. In addition, we find the steady-state analytic solution, which is linearly stable. We also successfully simulate the evolution of photon spectra without artificial viscosity. We find that photons rapidly lose their energy by ICS with continuously forming solitary structures in frequency-space. The solitary structures have the logarithmically same width characterized by an electron temperature. The energy transfer from photons to plasma is more effective for broader spectrum of photons such as expected in astrophysical situations.