| 著者名 | Authors | 所属機関名 | 所属機関名(欧文) | |
| 1 | #平原/聖文 | Hirahara/Masafumi | 立教大学理学部物理学科 | Department of Physics, College of Science, Rikkyo University |
| 2 | 笠原/禎也 | Kasahara/Yoshiya | 京都大学大学院情報学研究科通信情報システム専攻 | Deptartment of Communications and Computer Engineering, Kyoto University |
| 5 | F5 | Pickett/Jolene S. | K5 | Department of Physics and Astronomy, University of Iowa |
| 8 | POLAR-TIDE チーム | POLAR-TIDE Team | polar magnetosphere, as many works have reported. | cusp/cleft and then gradually decreased in the convection |
講演予稿:
地球電離圏から磁気圏へのイオン供給の重要な現象の一つは、太陽
風流入領域である電離圏高度カスプでの電離圏起源イオンの加速・
流出である。この講演では、米国のＰＯＬＡＲ衛星で観測された電
離圏起源イオンの磁場垂直方向への加速に伴う流出現象の特徴を、
高精度３次元速度分布関数測定を用い詳細に調査し、更に、イオン
加速の最有力候補とされるプラズマ波の特性、強度・空間分布を、
イオンデータと同時に得られた波動観測結果を基に調べ、これらの
比較と、波動データから理論的に予想されるイオン加速率から、電
離圏起源イオンの加速機構を議論する。特に、従来の静電イオンサ
イクロトロン波による加速説の正当性に重点を置き、報告を行う。
abstract:
Characteristics of the upflowing ionospheric ion (UFI)
conic events in the cusp/cleft at altitude of 5000 km are
discussed mainly on the basis of the observational results
by the thermal ion dynamics experiment (TIDE) and the
multichannel analyzer of the plasma wave instrument
(PWI-MCA) on board the POLAR satellite. The energy and
pitch angle distributions of UFI conics observed by TIDE
and their latitudinal variations showed that the transverse
ion energization (TIE) is a dominant process in the
cusp/cleft to effectively supply ionospheric ions into the
polar magnetosphere, as many works have reported.
Several important properties are presented in this paper.
The energies (from a few eV to several tens of eV) and cone
angles of the conics abruptly increased at the edge of the
cusp/cleft and then gradually decreased in the convection
direction in different manners for H+ and O+. Namely, the
variations of the O+ properties are more gradual than those
of H+. It is also interesting that the energies and
cone angles of O+ are larger than those of H+ at a given
time/position. These features are probably due to both of
following effects
Plasma convection transports the conic
fluxes from the most upstream cusp/cleft region to the
downstream, and the TIE efficiency varies dependently on
the locations (altitude and latitude). Broadband
electrostatic wave emissions measured by PWI-MCA with a
high-time resolution correlated well with the appearance
and energy variations of the UFI conics, which implies that
the ionospheric ions could be energized over a wide spatial
range in the 5000 km-altitude cusp/cleft. It is also
noteworthy that multiple TIE regions are seen repeatedly
during some of the cusp/cleft crossings and always
well-correlated with enhancements of wave activity. The
comparison of the TIDE and PWI-MCA observations provide two
new insights
The spatial distributions of the TIE and UFI
regions are latitudinally wider in the cusp/cleft than
expected, and the energization rates are dependent on
relative locations in the cusp/cleft, altitudes, and ion
species.
キーワード:
磁気圏電離圏結合、電離圏起源イオン、イオン流出、プラズマ加速・加熱、プラズマ波動、カスプ・クレフト
Keywords:
Magnetosphere-ionosphere coupling, ionosphere-origin ion, ion escape, plasma acceleration/heating, plasma wave, cusp