Wave‐Particle Interaction of Alfvén Waves in Jupiter's Magnetosphere: Auroral and Magnetospheric Particle Acceleration
Wave‐Particle Interaction of Alfvén Waves in Jupiter's Magnetosphere: Auroral and Magnetospheric Particle Acceleration
复制标题
DOI：
10.1029/2018ja025948
复制
发表时间：
2018-11
期刊：
影响因子：
--
通讯作者：
J. Saur;S. Janser;A. Schreiner;G. Clark;B. Mauk;P. Kollmann;R. Ebert;F. Allegrini;J. Szalay;S. Kotsiaros
中科院分区：
文献类型：
--
作者：
J. Saur;S. Janser;A. Schreiner;G. Clark;B. Mauk;P. Kollmann;R. Ebert;F. Allegrini;J. Szalay;S. Kotsiaros
我们调查的空间和时间尺度上发生的阿尔文波的波粒子相互作用在木星的磁层。我们考虑电子，质子和氧离子和研究区域沿着磁通量管等离子体是dennium，即赤道等离子体片，等离子体是最稀释的，也就是说，在电离层以上，极光粒子加速预计会发生。我们发现，在偶极L-壳层约为30，电子惯性长度尺度在极光区是占主导地位的规模，这表明电子朗道阻尼动力阿尔文波可以发挥重要作用，在转换场能量到极光粒子加速。这一机制与朱诺号经常观测到的宽带双向电子分布一致。由于木星磁层中的交换驱动质量传输，其磁层-电离层耦合预计大多数情况下不会处于局部力平衡状态。这可能是阿尔文驱动的随机加速度与不太频繁发生的局部强制平衡的静态单能量单向加速度相比起主导作用的关键原因。大约L = 30以外，离子回旋周期是占主导地位的规模表明，重离子的离子回旋阻尼在加热磁层等离子体中起着重要作用。我们还提出了动力学Alfvén波的色散关系和偏振关系的属性，包括由于安培定律中的位移电流的相对论修正的重要影响。
We investigate spatial and temporal scales at which wave‐particle interaction of Alfvén waves occurs in Jupiter's magnetosphere. We consider electrons, protons, and oxygen ions and study the regions along magnetic flux tubes where the plasma is the densest, that is, the equatorial plasma sheet, and where the plasma is the most dilute, that is, above the ionosphere, where auroral particle acceleration is expected to occur. We find that within a dipole L‐shell of roughly 30, the electron inertial length scale in the auroral region is the dominating scale, suggesting that electron Landau damping of kinetic Alfvén waves can play an important role in converting field energy into auroral particle acceleration. This mechanism is consistent with the broadband bidirectional electron distributions frequently observed by Juno. Due to interchange‐driven mass transport in Jupiter's magnetosphere, its magnetosphere‐ionosphere coupling is expected to be mostly not in local force balance. This might be a key reason for the dominant role of Alfvénically driven stochastic acceleration compared to the less frequently occurring, locally forced‐balanced, and thus static mono‐energetic unidirectional acceleration. Outside of approximately L = 30, the ion gyroperiod is the dominating scale suggesting that ion cyclotron damping of heavy ions plays a major role in heating magnetospheric plasma. We also present properties of the dispersion relationship and the polarization relationships of kinetic Alfvén waves including the important effects from the relativistic correction due to the displacement current in Ampère's law.