Triggering mechanism of magnetic reconnection in a collisionless plasma

无碰撞等离子体中磁重联的触发机制

• 批准号: 10680468
• 负责人: HORIUCHI Ritoku
• 金额: $ 0.83万
• 依托单位: National Institute for Fusion Science
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10680468/
• 关键词: collisionless plasma; magnetic reconnection; particle simulation; anomalous resistivity; particle kinetic effect; ion Larmor radius; drift-kink instability; anomalous ion heating; 非等方イオン加熱; プラズマ不安定性; 外部駆動電場; 波粒子相互作用

Triggering mechanism of magnetic reconnection in a collisionless plasma is investigated by means of three-dimensional electromagnetic particle simulation. Main results are summarized as follows.A. There exist two types of triggering mechanisms which break the frozen-in condition of magnetic field and lead to magnetic reconnection in a collisionless plasma. One is due to the wave-particle interaction which is a cause of anomalous resistivity in the current sheet. The other is due to the particle kinetic effect which becomes significant in a particle scale such as an electron collisionless skin depth and an ion Larmor radius.B. When there is not any driving source, two kinds of plasma instabilities grow in the current layer, I.e., the lower hybrid drift instability (LHDI) and the drift kink instability (DKI) instability. The LHDI grows in the periphery of the current layer, but it can not penetrate into a high beta region in the vicinity of the neutral sheet. The DKI is excited near the neutral sheet in a late period as a result of the nonlinear deformation of the current sheet by the LHDI, and can be a cause of anomalous resistivity, leading to collisionless reconnection at the neutral sheet.C. When an external driving field exists, the convective electric field penetrates into the current layer through the particle kinetic effect and collisionless reconnection is triggered by the convective electric field earlier than the DKI is excited. The growth rate of the DKI becomes larger compared with no driving field case, due to the compression of current layer by the convergent plasma flow.D. The anisotropic ion distribution is formed through the anomalous ion heating by the DKI.

采用三维电磁粒子模拟的方法研究了无碰撞等离子体中磁重联的触发机制。主要研究结果总结如下：在无碰撞等离子体中，有两种类型的触发机制打破磁场冻结状态，导致磁重联。一种是由于波粒相互作用，这是电流片中电阻率异常的原因。另一个是由于粒子动力学效应，它在粒子尺度上变得重要，如电子无碰撞的趋肤深度和离子拉莫尔半径。当没有驱动源时，电流层会产生两种等离子体不稳定性，即低混合漂移不稳定性（LHDI）和漂移扭结不稳定性（DKI）。LHDI生长在电流层的外围，但不能渗透到中性层附近的高β区。由于LHDI对电流片的非线性变形，DKI在后期在中性点片附近被激发，并且可能是异常电阻率的原因，导致中性点片无碰撞重接。当外部驱动场存在时，对流电场通过粒子动力学效应渗透到电流层，在DKI被激发之前，对流电场就触发了无碰撞重联。由于汇聚等离子体流对电流层的压缩，与无驱动场情况相比，DKI的生长速度变大。各向异性离子分布是通过DKI的异常离子加热形成的。

项目成果

R.Horiuchi: "Particle Simulation on a Large Spatiotemporal Scale" J.Plasma and Fusion Research. 74・8. 836-843 (1998)

R.Horiuchi：“大时空尺度的粒子模拟”J.Plasma and Fusion Research 74・8（1998）。

R.Horiuchi: "Kinetic Stabilization of Tilt Disruption in Field-Reversed Configurations" Nuclear Fusion. 39(印刷中). (1999)

R.Horiuchi：“场反转结构中倾斜破坏的动力学稳定”核聚变39（出版中）。

R.Horiuchi: "Collisionless magnetic reconnection in the presence of external driving flow" J.Plasma Phys.61(印刷中). (1999)

R.Horiuchi：“存在外部驱动流时的无碰撞磁重联”J.Plasma Phys.61（出版中）。

R. Horiuchi: "Kinetic Stabilization of Tilt Disruption in Field-Reversed Configuration"Nucl. Fusion. 39. 2083-2088 (1999)

R. Horiuchi：“场反转配置中倾斜破坏的动力学稳定”Nucl。

R.Horiuchi and T.Sato: "Collsionlles magnetic reconnection in the presence of external driving flow"J. Plasma Phys.. 61. 415-423 (1999)

R.Horiuchi 和 T.Sato：“存在外部驱动流时的 Collsionlles 磁重联”J。