Observations of charged particle precipitation into the auroral zone
Observations of charged particle precipitation into the auroral zone
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DOI：
10.1029/ja076i016p03612
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发表时间：
1971-06
影响因子：
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通讯作者：
L. Frank;K. Ackerson
中科院分区：
文献类型：
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作者：
L. Frank;K. Ackerson
一组灵敏的静电分析仪安装在地球卫星印第安5号的近极地低空轨道上。在极光区和极帽区以及外辐射区，分别和同时测量了5 - 100 - 50，000 eV能量范围内质子和电子强度的能谱和角分布，具有良好的时间和能量分辨率。利用完全颜色编码的能量-时间（E-t）谱图来呈现和有效地消化大量的个体强度测量。几个主要的观测结果是：（1）在傍晚扇区，在相对磁静止期间，电子沉淀模式通常以两个或多个低能电子沉淀带为特征，Kp = 0 - 2。(2)随着磁活动的增加，Kp从3到4+，这些沉淀电子强度的“带”变得更加强烈，并且通常不那么明确，相对于在静止期观察到的那些。(3)在这些时期的相对磁扰动，一个持久的倒“V”子结构的E-t频谱图是显而易见的。该子结构显示出峰值差分强度的电子能量随着时间的推移而明确增加，达到最大能量通常为千电子伏，随后该能量下降。(4)偶尔一个相对无结构，广泛的降水模式，观察到在当地傍晚在磁干扰期间。(5)在当地傍晚地区，质子降水的主导带通常位于内部，即，向赤道方向，低能电子沉淀的终止。(6)据观测，在傍晚时分，流入地球高层大气的能量在磁静止期低至101 erg（cm 2 sec）−1，而在扰动期则高达10250 erg（cm 2 sec）−1。(7)在上午晚些时候部门的电子降水的整体特征一般是更分散和不那么强烈，相对于那些在当地晚上观察到的。(8)上午晚些时候的降水模式的特点往往是一个substructure，不跨越整个降水区的宽度，显示减少平均电子能量增加不变的纬度。(9)在上午晚些时候的部门的电子降水往往是由一个非常强烈的，低能量电子强度的窄带限制在其高纬度边缘。这种强烈而独特的结构的典型宽度为20至30公里。电子光谱和密度与在遥远的磁鞘中观察到的相似。这些意见进行了讨论，以前的结果与类似的仪器在很大的距离内的地球磁层磁赤道附近的极光等离子体的源区和机制的影响。
An array of sensitive electrostatic analyzers was borne on the earth satellite Injun 5 in a nearly polar low-altitude orbit. The energy spectrums and angular distributions of proton and electron intensities over the energy range 5≲E≲50,000 ev were measured separately and simultaneously with good temporal and energy resolutions over the auroral zones and polar cap regions and within the outer radiation zone. Fully color-coded energy-time (E-t) spectrograms are utilized to present and effectively digest a massive body of individual intensity measurements. Several of the principal observational results were: (1) In the late evening sector the electron precipitation patterns are usually characterized by two or more bands of low-energy electron precipitation during periods of relative magnetic quiescence, Kp≃0 to 2. (2) With increasing magnetic activity, Kp≃3 to 4+, these ‘bands’ of precipitated electron intensities become more intense, and often less well defined, relative to those observed during quiescent periods. (3) During these periods of relative magnetic disturbance, a persistent inverted ‘V’ substructure in the E-t spectrograms is evident. This substructure displays a well-defined increase of the electron energy for peak differential intensities with time to a maximum energy usually ∼kiloelectron volts followed by a subsequent decrease of this energy. (4) Occasionally a relatively structureless, broad precipitation pattern is observed at late local evening during magnetically disturbed periods. (5) In the late local evening sector the dominant band of proton precipitation is often located just inside, i.e., equatorward of, the termination of low-energy electron precipitation. (6) Energy influxes into the earth's upper atmosphere during late evening have been observed to be as low as ≲1 erg (cm2 sec)−1 during magnetic quiescence and as high as ≃250 ergs (cm2 sec)−1 for disturbed periods. (7) The over-all features of electron precipitation in the late-morning sector are generally more diffuse and less intense relative to those observed during local evening. (8) The late-morning precipitation patterns are often characterized by a subtructure, not spanning the width of the entire precipitation region, that displays decreasing average electron energies with increasing invariant latitudes. (9) The electron precipitation in the late morning sector is often bounded at its high-latitude edge by a remarkably intense, narrow band of low-energy electron intensities. Typical widths of this intense, unique structure are ∼20 to 30 km. The electron spectrums and densities are similar to those observed in the distant magnetosheath. These observations are discussed in terms of previous results gained with similar instrumentation at great distances within the earth's magnetosphere near the magnetic equator and the implications concerning the source regions and mechanisms for the auroral plasmas.