Teste Alexandra, Parks George K
Space Sciences Laboratory, University of California, Berkeley, CA 94720-7450, USA.
Phys Rev Lett. 2009 Feb 20;102(7):075003. doi: 10.1103/PhysRevLett.102.075003.
Relevant new clues to wave-particle interactions have been obtained in Earth's plasma sheet (PS). The plasma measurements made on Cluster spacecraft show that broadband (approximately 2-6 kHz) electrostatic emissions, in the PS boundary layer, are associated with cold counterstreaming electrons flowing at 5-12x10(3) km s(-1) through hot Maxwellian plasma. In the current sheet (CS), electromagnetic whistler mode waves (approximately 10-80 Hz) and compressional Alfvén waves (<2 Hz) are detected with flat-topped electron distributions whose cutoff speeds are approximately 15-17x10(3) km s(-1). These waves are damped in the central CS where |B|<or=1.5 nT, plasma beta approximately 100, and electron distributions isotropic. Three mechanisms are at work: the beta-dependent lower hybrid drift instability (LHDI), acceleration of electrons along the B field by the LHD waves and whistler mode emissions triggered by the cyclotron resonance instability.
在地球等离子体片（PS）中已获得了有关波粒相互作用的相关新线索。在“星簇”航天器上进行的等离子体测量表明，在PS边界层中，宽带（约2 - 6千赫）静电辐射与以5 - 12×10³千米/秒的速度穿过热麦克斯韦等离子体的冷反向流动电子有关。在电流片（CS）中，检测到电磁哨声波（约10 - 80赫兹）和压缩阿尔文波（<2赫兹），其平顶电子分布的截止速度约为15 - 17×10³千米/秒。这些波在|B|≤1.5纳特、等离子体β约为100且电子分布各向同性的中央CS中被衰减。有三种机制在起作用：与β相关的低杂化漂移不稳定性（LHDI）、由LHD波沿B场对电子的加速以及由回旋共振不稳定性触发的哨声波发射。
