Dissipation measures in weakly collisional plasmas
Dissipation measures in weakly collisional plasmas
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DOI：
10.1093/mnras/stab1516
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发表时间：
2021-01
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影响因子：
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通讯作者：
O. Pezzi;Haoming Liang;J. Juno;C. Vásconez;-. LucaSorriso;Valvo;D. Perrone;S. Servidio;V. Roytershteyn;J. TenBarge;William;Matthaeus
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作者：
O. Pezzi;Haoming Liang;J. Juno;C. Vásconez;-. LucaSorriso;Valvo;D. Perrone;S. Servidio;V. Roytershteyn;J. TenBarge;William;Matthaeus
弱碰撞等离子体中能量耗散和相关加热的物理基础知之甚少。在这里，我们比较和对比的几种措施，已被用来表征能量耗散和kineticscale转换等离子体中的一套动力学数值模拟描述磁重联和衰减等离子体湍流。我们采用三种不同的数值代码，也可以包括粒子间的碰撞：全动力学粒子在细胞vpic，全动力学连续Gkeyll，和欧拉混合Vlasov-Maxwell（HVM）代码。我们区分i）四个基于能量的参数，其定义与等离子体的流体描述中的能量传递有关，以及ii）四个基于分布函数的参数，需要粒子速度分布函数的知识。有PIC和连续重联模拟中获得的耗散措施之间的总体协议，由于在两个模拟中的二次岛的存在/不存在略有差异。在重联模拟和自洽的电流片，在湍流中形成的签名之间也有许多定性的相似之处，虽然后者表现出显着的变化相比，重联的结果。所有的参数证实，耗散发生在强磁应力区域附近，从而表现出局部相关性。与基于能量的代理相比，基于分布函数的测量显示出更宽的宽度，这表明能量转移在相干结构处是共定位的，但可以影响更宽区域中的粒子分布函数。最后讨论了粒子间碰撞对这些参数的影响。
The physical foundations of the dissipation of energy and the associated heating in weakly collisional plasmas are poorly understood. Here, we compare and contrast several measures that have been used to characterize energy dissipation and kineticscale conversion in plasmas by means of a suite of kinetic numerical simulations describing both magnetic reconnection and decaying plasma turbulence. We adopt three different numerical codes that can also include inter-particle collisions: the fullykinetic particle-in-cell vpic, the fully-kinetic continuum Gkeyll, and the Eulerian Hybrid Vlasov-Maxwell (HVM) code. We differentiate between i) four energy-based parameters, whose definition is related to energy transfer in a fluid description of a plasma, and ii) four distribution function-based parameters, requiring knowledge of the particle velocity distribution function. There is overall agreement between the dissipation measures obtained in the PIC and continuum reconnection simulations, with slight differences due to the presence/absence of secondary islands in the two simulations. There are also many qualitative similarities between the signatures in the reconnection simulations and the self-consistent current sheets that form in turbulence, although the latter exhibits significant variations compared to the reconnection results. All the parameters confirm that dissipation occurs close to regions of intense magnetic stresses, thus exhibiting local correlation. The distribution function-based measures show a broader width compared to energy-based proxies, suggesting that energy transfer is co-localized at coherent structures, but can affect the particle distribution function in wider regions. The effect of inter-particle collisions on these parameters is finally discussed.