论文标题
动力学模拟中的噪声诱导的磁场饱和度
Noise-Induced Magnetic Field Saturation in Kinetic Simulations
论文作者
论文摘要
蒙特卡洛方法通常用于数值整合动力学方程，例如血浆动力学方程的粒子中的粒子方法，但是这些方法会遭受将计数噪声引入溶液的引入。我们报告了一个警示性的故事，即计算噪声改变了由不稳定的等离子体束驱动的动力学不稳定性的非线性饱和度。由于电流密度的采样误差，我们在分辨不足的粒子中模拟中发现了饱和的磁场。噪声引起的磁场是异常的，因为磁场在连续动力学中潮湿并增加了粒子计数粒子中的粒子模拟。饱和状态的这种修饰对此处考虑的简单等离子体系统以外的一系列天体物理现象具有影响，并且它强调了在使用粒子方法进行动力学方程时必须采取的护理。
Monte Carlo methods are often employed to numerically integrate kinetic equations, such as the particle-in-cell method for the plasma kinetic equation, but these methods suffer from the introduction of counting noise to the solution. We report on a cautionary tale of counting noise modifying the nonlinear saturation of kinetic instabilities driven by unstable beams of plasma. We find a saturated magnetic field in under-resolved particle-in-cell simulations due to the sampling error in the current density. The noise-induced magnetic field is anomalous, as the magnetic field damps away in continuum kinetic and increased particle count particle-in-cell simulations. This modification of the saturated state has implications for a broad array of astrophysical phenomena beyond the simple plasma system considered here, and it stresses the care that must be taken when using particle methods for kinetic equations.
