藉由卡西尼太空船MIMI/LEMMS觀測資料分析土星高能電漿入射來源之統計

A Statistical Study of the Source Regions of the Saturnian Injection Events from Cassini MIMI/LEMMS Measurements

鄒佳諭(Chia-Yu Tzou)

指導教授 ： 葉永烜

國立中央大學/地球科學學院/太空科學研究所/碩士(2012年)

摘要

卡西尼(Cassini)太空船上的太空電漿量測儀器(MIMI/LEMMS)在土星磁層中觀測到頻繁的高能電子及離子入射，這是土星磁層的一大特色。這樣的電漿入射事件可以由被稱為交換不穩定(interchange instability)的機制所引發。而交換不穩定可以歸因於主要源自土星冰衛星之一土衛二(Enceladus)的電漿在土星磁層中之質量負載。
接續Mauk (2005)、Paranicas (2007)及Muller (2010)等人的研究，我們設法得到2010年觀測資料中電漿入射事件的入射方位及觀測年齡。本研究中我們總共分析了25個年輕的電漿入射事件。卡西尼太空船在2010年的軌道傾角不大，換句話說，這段期間內卡西尼太空船在接近赤道平面上繞行。卡西尼太空船2010年繞行的範圍皆在土星磁層的同一區域，導致分析年輕入射事件得到的入射方位多數被限制在土星傍晚區域。在此，我們也發現一些似乎為土星磁層中一連串電漿入射爆發的“電漿入射群”。

關鍵字

電漿入射 ； 磁層 ； 卡西尼 ； 土星

並列摘要

One of the special features of the Saturnian magnetosphere is the frequent injection of energetic ions and electrons observed by the plasma instruments onboard the Cassini spacecraft (i.e., MIMI./LEMMS). Such injection events could be triggered by the so-called interchange instability due to the mass-loading effect of the ions originated from the icy satellite, Enceladus.
Following the work of Mauk et al. (2005), Paranicas et al. (2007) and Muller et al. (2010), we try to extract the injection site and age of injection signatures for the period during year 2010. Here we choose to analyze young events only. There are 22 inbound injection events and 3 outbound events studied. In 2010 the inclination of Cassini is small and the spacecraft orbits are close to the equatorial plane. Because the orbits of the Cassini spacecraft moved through the same region of the Saturnian magnetosphere in 2010, the extracted injection sites of the selected young events are limited to be mostly in the dusk region. And we found there are some “injection-clusters” that appear to be injection bursts in Saturn’s magnetosphere.

並列關鍵字

injection events ； MIMI/LEMMS ； Cassini ； magnetosphere ； Saturn

參考文獻

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