Higher moment equations and the distribution function of the solar‐wind plasma
Higher moment equations and the distribution function of the solar‐wind plasma
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DOI：
10.1029/ja076i031p07503
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发表时间：
1971-11
影响因子：
--
通讯作者：
Y. Whang
中科院分区：
文献类型：
--
作者：
Y. Whang
对于无碰撞的热传导等离子体，分布函数f关于磁场方向是圆柱对称的。如果假设f = [1 + c <$h（c）] f0，其中f0是双麦克斯韦分布函数，c <$h是固有速度c的平行分量，h是c的偶函数，那么f的四阶矩可以表示为低阶矩的简单函数。因此，在三阶矩方程中没有出现高阶矩项。得到的两个三阶矩方程形式简单，与其它低阶矩方程构成一个封闭的矩方程组。新方程可用于研究太阳风质子的热各向异性和热通量。圆柱对称分布函数f = [1 + c h（c）]f0的一种特殊情况被发现类似于从太阳风数据重建的质子分布函数，这种相似性证明了解耦矩方程所需的假设。
For a collisionless, heat-conducting plasma, the distribution function f is cylindrically symmetric about the direction of the magnetic field. If one assumes f = [1 + c∥ h(c)] f0 where f0 is the bi-Maxwellian distribution function, c∥ is the parallel component of the intrinsic velocity c, and h is an even function of c, then the fourth moments of f can be expressed as simple functions of lower moments. Thus no higher moment terms appear in the third moment equations. The two third moment equations, which are obtained in a simple form, join other lower moment equations to form a closed set of moment equations. The new equations can be used to study the thermal anisotropy and the heat flux of the solar-wind proton. A special case of the cylindrically symmetric distribution function f = [1 + c∥h(c)]f0 is found to resemble the proton distribution function reconstructed from solar-wind data, and this resemblance justifies the assumption needed for decoupling the moment equations.