Study on the Impulsive Plasma Wave Burst Phenomena Associated with Auroras

与极光相关的脉冲等离子体波爆发现象的研究

• 批准号: 09440170
• 负责人: ONO Takayuki
• 金额: $ 4.35万
• 依托单位: Tohoku University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1997
• 资助国家: 日本
• 起止时间: 1997 至 1998
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09440170/
• 关键词: Akebono (EXOS-D); auroal ionosphere; electrostatic Whistler mode; impulsive burst; database; beam plasma instability; low energy electrons; plasma waves; 静電的ホイッスラーモード波; 瞬時性バースト; 温度異方性型プラズマ不安定; プラズマ波動; 静電的ホイッスラ-モード波

Plasma Waves and Sounder (PWS) Experiment on board the Akebono (EXOS-D) satellite has been successfully carried out through the entire regions along the satellite orbit with initial perigee, apogee and inclination of 300 kin, 10,500 km and 68ﾟ, respectively ; the observation have also been made in the polar ionosphere covering from low to high altitude ranges. The high altitude observation in the polar region is aimed to explore the acceleration region of auroral particles ; in the low altitude polar ionosphere, on the other hand, observations have been made for sounding the energy dissipation region related to formation of auroras and ionospheric disturbances. Strong interactions of the auroral particles with ionospheric plasma with neutral gases makes disturbed states in entire altitude range of the auroral thermosphere.The present research work has been focused on the emissions of impulsive plasma wave burst (IPB) observed in the frequency range of the whistler mode waves in the low … More altitude polar ionosphere below 2,000 km by using electric field detecting antenna of plasma waves and sounder experiment (PWS) on-board the Akebono satellite. Within the research period form 1997 to 1998, the research activities have been directed to the theoretical research of the wave particle interactions in the polar ionosphere as well as data archiving and analysis of PWS data from the Akebono (EXOS-D) satellite.The results of the data analysis shows that the emissions of IPB are frequently observed indicating a group of intense impulses with electric field amplitude of several hundreds muV/m to several mV/m. The propagation directions identified by using the spin modulation effect on the electric fields detected with the two sets of dipole antennas showed that IPB's belong to the electrostatic whistler mode plasma waves whose wave number vectors have a large propagation angle from the ambient magnetic field. The origin of impulsive signatures of emissions can be attributed to the manifestation of the short lived nature of excited waves ; namely, the duration time is estimated to be in the range from 20 to 200 msec. These major characteristics of IPB are consistently interpreted with the theorecal approach to the whistler mode branch of the plasma waves, calculating the dispersion relation in the regime of electrostatic whistler mode waves under the condition of beam plasma instability related to the low energy electron beam in the F-region and topside ionosphere of the polar region. The short lived feature of IPB is understood as being resulted by severe damping effects of the electrostatic whistler mode plasma waves when the waves enter into the space of non free energy. The observation region of IPB is then limited in the region close to plasma instability that is possibly caused by the low energy electrons associated with auroras. Though the quest for origin of the impulsive generation of low energy electrons is deferred for future studies, it is inferred that the auroral particle precipitation into the polar ionosphere generates suprathermal electron beams forming successive groups with periodic modulation. Less

Akebono（EXOS-D）卫星上的等离子体波和探测器实验已成功地在卫星轨道的整个沿着区域进行，该卫星轨道的初始近地点、远地点和倾角分别为300公里、10，500公里和68公里;还在从低到高高度范围的极地电离层进行了观测。在极区的高空观测旨在探索极光粒子的加速区;另一方面，在低空极区电离层进行了观测，探测与极光形成和电离层扰动有关的能量耗散区。极光粒子与电离层等离子体和中性气体的强烈相互作用使极光热层在整个高度范围内处于扰动状态，本文着重研究了在低纬大气中哨声波频率范围内观测到的脉冲等离子体波爆发（IPB）的发射。 ...更多信息 利用Akebono卫星上的等离子体波电场探测天线和探测器实验，对2，000公里以下的高空极地电离层进行了探测。在1997年至1998年的研究期间，这些研究活动主要是针对极地电离层中波粒相互作用的理论研究，以及Akebono（EXOS-D）的PWS数据的数据存档和分析数据分析的结果表明，IPB的发射经常被观察到，表明一组强脉冲，电场幅度为几几百μ V/m到几mV/m。利用自旋调制效应对两组偶极天线探测到的电场进行了传播方向的分析，结果表明IPB属于静电哨声模式等离子体波，其波数矢量与周围磁场有较大的传播角。发射脉冲特征的起源可以归因于激发波的短暂本质的表现;即，持续时间估计在20到200毫秒的范围内。用等离子体波哨声模分支的理论方法解释了IPB的这些主要特性，计算了在F区和极区电离层顶面低能电子束引起的束流等离子体不稳定性条件下静电哨声模波的色散关系。IPB的短寿命特性被认为是静电哨声模式等离子体波进入非自由能空间时的严重阻尼效应造成的。IPB的观测区域被限制在接近等离子体不稳定性的区域，这可能是由与极光相关的低能电子引起的。虽然寻求起源的脉冲产生的低能电子被推迟到未来的研究，据推测，极光粒子沉淀到极地电离层产生超热电子束形成连续的群体与周期性调制。少

项目成果

Yamamoto, M., T.Oho, H.Oya, R.T.Tsunode, M.F.Larsen, S.Fukao, and M.Yamamoto: "Structures in sporadic-E observed with an impedance probe during the SEEK campaign : Comparison with neutral-wind and radar-echo observations" Geophys. Res.Lett.25. 1781-1784 (

Yamamoto, M.、T.Oho、H.Oya、R.T.Tsunode、M.F.Larsen、S.Fukao 和 M.Yamamoto：“SEEK 活动期间用阻抗探头观察到的零星 E 结构：与中性风和中性风的比较

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Yamamoto, M., T.Ono, H.Oya, R.T.Tsunoda, M.F.Larsen, S.Fukao, and M.Yamamoto: "Structures in sporadic-E observed with an itnpedance probe during the SEEK campaigh : Comparisions with neutral-wind and radar-echo observations" Geophys.Res.Lett.vol.25. 1781-

Yamamoto, M.、T.Ono、H.Oya、R.T.Tsunoda、M.F.Larsen、S.Fukao 和 M.Yamamoto：“SEEK 活动期间用 itnpedance 探头观察到的零星 E 结构：与中性风和风的比较

T.Ono,A.Morioka,A.Kumamoto,H.Oya,K.Kobayashi,T.Obara and T.Nakagawa: "Plasma Waves and Sounder(PWS)Experiment on-board the Planet-B Mars Orbiter" Earth,Planets and Space. 50. 213-222 (1998)

T.Ono、A.Morioka、A.Kumamoto、H.Oya、K.Kobayashi、T.Obara 和 T.Nakakawa：“Planet-B 火星轨道飞行器上的等离子波和发声器（PWS）实验” 地球、行星