Plasma Wave Observations at Comet Giacobini-Zinner
Plasma Wave Observations at Comet Giacobini-Zinner
复制标题
贾科比尼-津纳彗星的等离子体波观测
作者：
F. Scarf;F. Coroniti;C. Kennel;D. Gurnett;W. Ip;E. Smith
国际彗星探测器（ICE）上的等离子体波仪器几乎连续地探测到强烈的离子声波爆发，当时航天器距离贾科比尼-辛纳彗星的核心不到200万公里。电磁哨声和低水平的电子等离子体振荡也被观察到在这个巨大的区域，似乎与重离子拾取。当ICE接近弓形激波的预期位置时，电磁波和静电波水平显著增加，但即使在这种湍流中，波动仪器也检测到具有熟悉弓形激波特征的结构，这些特征与局部电子加热现象的观测结果密切相关。就在可见的彗发之外，记录到了幅值与ICE等离子体波仪器所探测到的任何波一样高的宽带波。这些波可以解释ICE等离子体探测器在该区域观察到的显着的电子加热，并且这些强波粒相互作用的观测结果可以为有关彗发附近电离过程的长期问题提供答案。在最接近的地方，等离子体波仪器探测到宽带静电噪声和弱电子等离子体振荡的变化模式，产生了冷等离子体尾部外层的密度分布。在尾轴附近的等离子体波仪器也检测到了不均匀的灰尘影响的流量，并提出了一个初步的配置文件的Giacobini-Zinner灰尘分布为微米级的颗粒。
The plasma wave instrument on the International Cometary Explorer (ICE) detected bursts of strong ion acoustic waves almost continuously when the spacecraft was within 2 million kilometers of the nucleus of comet Giacobini-Zinner. Electromagnetic whistlers and low-level electron plasma oscillations were also observed in this vast region that appears to be associated with heavy ion pickup. As ICE came closer to the anticipated location of the bow shock, the electromagnetic and electrostatic wave levels increased significantly, but even in the midst of this turbulence the wave instrument detected structures with familiar bow shock characteristics that were well correlated with observations of localized electron heating phenomena. Just beyond the visible coma, broadband waves with amplitudes as high as any ever detected by the ICE plasma wave instrument were recorded. These waves may account for the significant electron heating observed in this region by the ICE plasma probe, and these observations of strong wave-particle interactions may provide answers to longstanding questions concerning ionization processes in the vicinity of the coma. Near closest approach, the plasma wave instrument detected broadband electrostatic noise and a changing pattern of weak electron plasma oscillations that yielded a density profile for the outer layers of the cold plasma tail. Near the tail axis the plasma wave instrument also detected a nonuniform flux of dust impacts, and a preliminary profile of the Giacobini-Zinner dust distribution for micrometer-sized particles is presented.