The charged-particle fluxes at auroral and polar latitudes and related low-frequency auroral kilometric radiation-type and high-frequency wideband emission
The charged-particle fluxes at auroral and polar latitudes and related low-frequency auroral kilometric radiation-type and high-frequency wideband emission
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极光和极纬度的带电粒子通量以及相关的低频极光千米辐射型和高频宽带发射
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发表时间：
1997
期刊：
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通讯作者：
H. Rothkaehl
中科院分区：
文献类型：
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作者：
N. Shutte;I. S. Prutensky;S. Pulinets;Z. Kłos;H. Rothkaehl
介绍了 APEX 航天器上同时观测 50 eV 至 20 keV 能量范围内的带电粒子通量（等离子体能量角谱仪，PEAS 实验）和 0.1 至 10 MHz 频率范围内的等离子体波（等离子体射电谱仪，PRS 3 实验）的结果。这些数据是在极地和极光纬度的黎明-黄昏和中午-午夜时段获得的。低频（LF）零星发射主要在低于当地陀螺频率的频率上，通常在极光椭圆区相对狭窄的纬度区间（∼5°–6°）内观察到。光谱波强度的最大值出现在~200 kHz 的频率处。观测到的发射光谱的零星特征与极光千米辐射 (AKR) 的报告非常相似，并且时间和空间发生意味着它与在更高海拔测量的 AKR 发射源的关系，就我们的波测量作为 LF AKR 型发射而言。对带电粒子能谱空间分布和极光椭圆纬度波谱变化的比较分析表明，低频AKR的产生应满足几个条件。这些条件与沉淀离子和电子通量的强度和能量以及反照率电子和电离层等离子体参数有关。在早晨极光椭圆形穿越期间，观察到了宽带高频发射和低频 AKR 型发射。在航天器远地点高度，在 IMF 向北的时期，在极冠区观察到强烈的电子降水和等离子噪声强度在等于或低于 fHe 的频率下的增加。这些降水和发射伴随着穿过极冠的水平电流，即所谓的 theta 结构。
The results of simultaneous observations of charged particle fluxes within the energy range 50 eV to 20 keV (plasma energy-angle spectrometer, PEAS experiment) and plasma waves within the frequency range 0.1 to 10 MHz (plasma radio spectrometer, PRS 3 experiment) on board the APEX spacecraft are presented. The data were obtained at polar and auroral latitudes in the dawn-dusk and noon-midnight time sectors. The low-frequency (LF) sporadic emission mainly on frequencies lower than the local gyrofrequency was commonly observed within a comparatively narrow latitude interval (∼5°– 6°) of the auroral oval. The maximum of spectral wave intensity was revealed at a frequency of ∼ 200 kHz. The sporadic character of the observed emissions, the spectra, are very similar to those reported for auroral kilometric radiation (AKR), and the temporal and spatial occurrences imply its relation to the source of AKR emissions measured at the higher altitudes, with regards to our wave measurements as LF AKR-type emissions. Comparative analysis of spatial distributions of charged particle energy spectra and variations of wave spectra at auroral oval latitudes showed that several conditions should be fulfilled for LF AKR generation. These conditions are related both to the intensity and energy of precipitating ion and electron fluxes, and to albedo electrons and the ionospheric plasma parameters. The wideband HF emission was observed together with the LF AKR-type emission during the morning auroral oval crossing. At spacecraft apogee altitudes, in the polar cap zone intense electron precipitations and an increase of plasma noise intensity at frequencies equal or below ƒHe were observed at the period when the IMF was northward These precipitations and emissions were accompanied by the horizontal currents crossing the polar cap, the so-called theta structure.