标题： 低β等离子体中低频动力学、磁重联和电子加热的简化流体-粒子方程 显示英文标题

标题： Reduced fluid-kinetic equations for low-frequency dynamics, magnetic reconnection and electron heating in low-beta plasmas

摘要： 提出的磁重联以及低β等离子体中低频动力学的一个最小模型。该模型结合了分析和计算的简洁性与物理可行性：它是等离子体β值约为电子-离子质量比的gyrokinetics的严格极限。该模型包含碰撞，并可用于碰撞和无碰撞重联区域。它包含gyrokinetic离子（不假设为冷离子），并通过电阻率或电子惯性（以占主导地位者为准）允许磁场线的拓扑重新排列。两流体动力学与电子动力学耦合——电子不假设为等温的，并由一个简化的漂移-动力方程描述。因此，该模型允许不可逆性和通过速度空间中的平行相位混合将磁能转化为电子热能。提供了关于各种自由能形式之间的交换及其转化为电子热能的分析。展示了如何在我们模型的各种极限下恢复撕裂不稳定性（无碰撞、半碰撞和完全电阻）的相关线性波和区域。提出了一种通过速度空间的Hermite表示来数值模拟我们方程的高效方法。表明速度空间中将形成小尺度，从而产生浅Hermite空间谱，由此推断出，在稳态或足够缓慢的动力学情况下，当碰撞性趋于零时，电子加热率将保持有限。 显示英文摘要

摘要： A minimal model for magnetic reconnection and, generally, low-frequency dynamics in low-beta plasmas is proposed. The model combines analytical and computational simplicity with physical realizability: it is a rigorous limit of gyrokinetics for plasma beta of order the electron-ion mass ratio. The model contains collisions and can be used both in the collisional and collisionless reconnection regimes. It includes gyrokinetic ions (not assumed cold) and allows for the topological rearrangement of the magnetic field lines by either resistivity or electron inertia, whichever predominates. The two-fluid dynamics are coupled to electron kinetics --- electrons are not assumed isothermal and are described by a reduced drift-kinetic equation. The model therefore allows for irreversibility and conversion of magnetic energy into electron heat via parallel phase mixing in velocity space. An analysis of the exchanges between various forms of free energy and its conversion into electron heat is provided. It is shown how all relevant linear waves and regimes of the tearing instability (collisionless, semicollisional and fully resistive) are recovered in various limits of our model. An efficient way to simulate our equations numerically is proposed, via the Hermite representation of the velocity space. It is shown that small scales in velocity space will form, giving rise to a shallow Hermite-space spectrum, whence it is inferred that, for steady-state or sufficiently slow dynamics, the electron heating rate will remain finite in the limit of vanishing collisionality.