巻号一覧
33 巻, 1 号
選択された号の論文の12件中1～12を表示しています
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T. Obayashi1981 年 33 巻 1 号 p. 1-2
発行日: 1981年
公開日: 2011/08/11
ジャーナル フリーPDF形式でダウンロード (132K) -
Part I. Observation of Plasma ResonancesHiroshi OYA, Takayuki ONO, Tetsuo KAMADA1981 年 33 巻 1 号 p. 3-25
発行日: 1981年
公開日: 2010/03/12
ジャーナル フリーThe stimulated plasma wave experiment (SPW) has been successfully carried out in the plasmasphere and the magnetosphere along the JIKIKEN (EXOS-B) satellite orbit where the plasma parameters indicate wide variety of the combination of the electron number density ranging from 1/cc to 104/cc, and the electron cyclotron frequency ranging from 6kHz to 200kHz.
The observed plasma resonances are: i) the upper hybrid resonance FUHR, ii) the plasma resonance FP, iii) the higher harmonics of the electron cyclotron resonance nFH, iv) the electrostatic resonance FQn, and v) the sequence of the diffuse resonance FDn. The upper hybrid resonances usually persists for long periods up to 125 msec and the electron cyclotron resonances are stimulated at frequency with the very high harmonic number n; sometimes, the nFH resonance takes place for n≥30.
The detection of the plasma resonance FP is more difficult compared with the case of the observation of the FUHR resonance due to the expanded wavelength of the electrostatic plasma waves near at FP. The observation of the diffuse resonances is the most difficult case in the magnetosphere since the energy of the plasma in the magnetosphere overcomes the electric field intensity generated by the SPW pulse transmission. All the features of the resonances reflect the characteristics of the magnetospheric plasma that contains the energetic and non-Maxwellian components of the particles. The measurement of the plasma resonance contributes to the detection of the local electron density, magnetic field intensity; conditions for the wave particle interactions are also analyzed from the duration features of the plasma resonances.抄録全体を表示PDF形式でダウンロード (2628K) -
Hiroshi OYA, Akira MORIOKA1981 年 33 巻 1 号 p. 27-35
発行日: 1981年
公開日: 2010/03/12
ジャーナル フリーThe plasma wave emissions of the electrostatic mode have been observed in a frequency range below the upper hybrid resonance frequency with the frequency gap characterized by the electron cyclotron frequency FH, ranging from FH to 2FH including (3/2)FH. The emission is here called the subsidiary UHR emissions. Considering the bandwidth, and the frequency gap between the upper hybrid mode wave frequency it is suggested that the subsidiary UHR emission is generated as a result of the nonlinear wave particle interactions between the upper hybrid mode waves, with the angular frequency ωUHR and the wave number κUHR, and the electrostatic plasma wave, with the angular frequency ωs and the wave number κs, under the resonant condition, as
ωUHR-ωs-(κUHR-κs)·V=n(2πFH)
where V is the electron beam velocity. The generated subsidiary emission that belongs to the electrostatic electron cyclotron harmonic mode, may be absorbed into the plasma. The subsidiary emission is, therefore, the manifestation of the heating processes of the magnetospheric plasma due to the beam of the high energetic particles.抄録全体を表示PDF形式でダウンロード (1141K) -
Akira MORIOKA, Hiroshi OYA, Sadao MIYATAKE1981 年 33 巻 1 号 p. 37-62
発行日: 1981年
公開日: 2010/03/12
ジャーナル フリーThe natural plasma wave astronomy mode (NPW-A) on board JIKIKEN (EXOS-B) launched on Sept. 16, 1978, are making observation of the planetary and solar radio waves in the frequency range from 10kHz to 3MHz using the long dipole antenna with length of 102m. The high resolution spectrum obtained by the NPW-A receiver provides important characteristics of the terrestrial kilometric radiation (TKR) that carries the information on the source region where TKR is generated.
When the source mechanism that the electrostatic waves near the upper hybrid frequency generated by auroral precipitating particle is converted in a form of the electromagnetic waves is considered, we can estimate the position of the TKR source from the measured spectrum. The height distribution of the source region derived from the frequency component of the radiation indicates the altitude range that varies in accordance with the geomagnetic activity, and ranging from 3, 000km to 12, 000km above the auroral ionosphere. The fine structure of TKR spectrum shows that the source with the dimension of 100km is moving down repeatedly toward the polar ionosphere with the average velocity of 5-10km/sec, and suggests that the source motion is closely related to the formation and the structure of the parallel electric field. The TKR emission sometimes coinsides with the intense upper hybrid emission around the satellite position at the inner edge of the dusk side plasmasheet, indicating that TKR has intimate relation to the energetic particle precipitation that generates the UHR waves; the precipitating particles may contribute to the development of the auroral field aligned currents.抄録全体を表示PDF形式でダウンロード (3841K) -
H. MATSUMOTO, S. MIYATAKE, K. TSURUDA, A. MORIOKA, J. OHTSU, H. OYA, I ...1981 年 33 巻 1 号 p. 63-72
発行日: 1981年
公開日: 2010/03/12
ジャーナル フリーInstrumentation, data processing and preliminary results of EXOS-B VLF wave receiver are presented. The VLF receiver is connected, by command, either to a long dipole antenna or to a loop antenna, and observes both electromagnetic and electrostatic waves in a frequency range between 150Hz and 9.5kHz. Up to the present time after the launch, various VLF phenomena including whistler echo trains, whistler triggered emissions, hiss, chorus, and possible power line harmonic radiation have been observed. In addition to these natural phenomena, artificial VLF waves excited by electron beam injection have also been observed.抄録全体を表示PDF形式でダウンロード (1774K) -
H. MATSUMOTO, K. HASHIMOTO, M. MORIKURA, I. KIMURA, T. MUKAI1981 年 33 巻 1 号 p. 73-87
発行日: 1981年
公開日: 2010/03/12
ジャーナル フリーCase studies on correlation between VLF plasma waves and energetic electrons are presented based on data observed by EXOS-B satellite. The frequency range of the observed VLF plasma waves is from 150Hz to 9.5kHz, while the measured energy range of electrons is from 5eV to 11keV. Data observed on specific four passes (Revs. 185, 273, 284, and 588) are examined. Especially data on Rev. 284 are shown in detail because both the VLF waves and energetic electrons are observed continuously over more than 5hr on that orbit. It is shown that band-limited hiss and discrete VLF emissions below a local cyclotron frequency are well correlated with 1 to 10keV electrons.抄録全体を表示PDF形式でダウンロード (4908K) -
I. KIMURA, K. HASHIMOTO1981 年 33 巻 1 号 p. 89-99
発行日: 1981年
公開日: 2010/03/12
ジャーナル フリーThis paper is concerned with preliminary results of a Doppler shift measurement of NWC signal by means of an instrument named “DPL” on board the EXOS-B satellite which was launched on September 16, 1978. Main purpose of this measurement is to detect the ionization ducts in the magnetosphere. From actually observed Doppler shift, it is found that the signals were mostly nonducted. Signal intensity and noise intensity at 22.3kHz have been also observed by DPL using two pairs of long dipole antennas, 103 and 70m tip-to-tip. Capacitance of the antenna has been measured by imposing a constant current at 22.3kHz to the antennas. From this capacitance measurement, plasmapause crossing of the satellite has been detected.抄録全体を表示PDF形式でダウンロード (956K) -
M. EJIRI, K. TSURUDA, Y. WATANABE, A. NISHIDA, T. OBAYASHI1981 年 33 巻 1 号 p. 101-110
発行日: 1981年
公開日: 2010/03/12
ジャーナル フリーIEF (Impedance and Electric Field) instrument onboard EXOS-B was designed to measure an antenna impedance and DC electric field and AC (low frequency) electric field using a long cylindrical antenna system. Preliminary impedance data show an upper hybrid resonance down to a few tens of kHz which corresponds to the electron density of about 10cm-3 around the plasmapause boundary, where DC electric field intensity changes abruptly as a same manner as observed by the S3 (Explorer 45) satellite. The location of the plasmapause determined by the observed density profile shows Kp-dependence.
AC electric field measurement using a dipole antenna with a tip-to-tip length of about 103m gave a variety of wave phenomena in the frequency range from 1Hz to 450Hz, such as driftwaves, plasmaspheric hiss, ion cyclotron waves et al., though they have not been clearly identified yet. Since the EXOS-B observations were undertaken inside, at the boundary, and outside of the plasmasphere in the midnight regions, those noises were very changeable in frequency, in intensity, and its frequency band width depending on the satellite location.抄録全体を表示PDF形式でダウンロード (1185K) -
I. AOYAMA, F. TOYAMA, T. TAKAHASHI, T. SAKURAI, Y. TONEGAWA, T. SAITO, ...1981 年 33 巻 1 号 p. 111-118
発行日: 1981年
公開日: 2010/03/12
ジャーナル フリーThe earth's magnetic field was measured by a triaxial fluxgate magnetometer on board the satellite JIKIKEN (EXOS-B), which was launched on September 16, 1978, to an eccentric orbit with the initial apogee of 30, 056km. Characteristic temporal deviations of the magnetic field from IGRF were observed by JIKIKEN at L-6 in the 20-23 MLT sector while Kp>2 during December 1-31, 1978. A comparison of Pi 2-substorm onsets observed at the Onagawa Magnetic Observatory with the 10 cases of the deviations called the enhanced events derives the enhanced field-aligned model that the events are due to a field-aligned current flowing downwards along the L≈6 shell in the premidnight sector, and that the current is intensified at the time of substorm onset. Discussions are briefly given on relations among the field-aligned current, Region 2, and an enhanced event observed in the post-midnight sector.抄録全体を表示PDF形式でダウンロード (751K) -
T. SAITO, K. YUMOTO, I. AOYAMA, F. TOYAMA, T. SAKURAI, T. TAKAHASHI, Y ...1981 年 33 巻 1 号 p. 119-124
発行日: 1981年
公開日: 2010/03/12
ジャーナル フリーBeing associated with a typical mini-substorm, a very-long-period Pi 2 event was observed simultaneously at both Onagawa, Japan, and the satellite, JIKIKEN, at 14-15 hUT on December 11, 1978. The fundamental period of the Pi 2 attained to 220 sec and the range of the substorm at Onagawa on the 23h local time meridian was only 2nT. The plasmapause was observed by JIKIKEN on the 21h local time meridian to be at L>6.3.
This Pi 2 event in the extreme case is well explained by such an odd-mode model that a temporal odd-mode torsional oscillation of the dipole-like field lines anchored in the auroral ovals is observed as Pi 2. The analysis reveals that the ignition region for this mini-substorm must be |X|>16RE in the magnetotail and that the tail-like configuration of the field line must be changed to the dipole-like one within several min. This event provides valuable information on one of the smallest cases of the magnetospheric substorm.抄録全体を表示PDF形式でダウンロード (503K) -
Haruya KUBO, Toshifumi MUKAI, Nobuki KAWASHIMA1981 年 33 巻 1 号 p. 125-143
発行日: 1981年
公開日: 2010/03/12
ジャーナル フリーCharged particle detectors (ESP) on board the Japanese sixth scientific satellite JIKIKEN have measured electron and ion fluxes in the energy ranges of a few eV up to 10keV and of 10eV up to 30keV, respectively, in the magnetosphere of L-shells from L≅2.5 to L≅8. Main results are: (1) On quiet days, significant fluxes of electrons and ions were rarely observed. (2) On disturbed days, intense fluxes of keV-electrons were observed at L≥4, suggesting a plasma injection from the plasma sheet. Ring current ions in the energy range above 1keV were also observed on disturbed days after magnetic storm.抄録全体を表示PDF形式でダウンロード (1872K) -
Nobuki KAWASHIMA, Atsuo USHIKOSHI, Yukio MURASATO, Akira MORIOKA, Hiro ...1981 年 33 巻 1 号 p. 145-159
発行日: 1981年
公開日: 2010/03/12
ジャーナル フリーBeam-plasma interaction experiment has been made in the magnetosphere by emitting an electron beam (100-200eV, 0.25-1.0mA) from the satellite “JIKIKEN” (EXOS-B). Various types of wave emissions are detected by a LF and HF wave detector. Two waves near at upper-hybrid frequency and at electron cyclotron frequency are detected in a low L-value region. In a higher L-value region, a harmonic generation of 16kHz is conspicuous, which is originated from the cathode heater power supply. The time variation and dependence on various parameters of the magnetosphere are studied.抄録全体を表示PDF形式でダウンロード (1498K)
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