摘要:

Recent observations have disclosed that the ionosphere over the aurora contains considerable fluxes of almost monoenergetic electrons at an energyE0∼ 10 kev. It is computed that such an energy distribution makes the topside ionosphere unstable to electrostatic plasma waves. The frequencies of these unstable waves are close to the local upper hybrid resonance frequency and the wavelengths λ are given by λ ≈ (2E0/m)1/2(4νc)−1∼10m. (νcis the electron cyclotron frequency.) If the monoenergetic flux equals (or exceeds) a critical value of ∼7 · 109cm−2sec−1ster−1(measured at 90° to the magnetic field), then the plasma waves can grow to an amplitude large enough to cause stochastic acceleration of a few electrons to energies ∼40–100 kev on a time scale of ∼10−2sec. The detection of such plasma instabilities is a straightfor

ISSN:0148-0227    

DOI:10.1029/JA073i021p06631

年代:1968

数据来源: WILEY

摘要:

Measurements have been made of the neutron intensities above the atmosphere at rocket altitudes with a moderated He³ neutron detector. The He³ proportional counter was encased in a polyethylene moderator, and the moderator and neutron detector were surrounded by a ring of charged particle counters to discriminate against neutrons produced in the detector assembly by galactic and solar cosmic rays. Flights were made from 1965–1967 at 0°, 20°, 50°, and 70° geomagnetic latitudes (λ). The neutron counting rates at these latitudes are 0.3,<0.7, 1.7, and 3.0 sec−1, respectively. These counting rates can be converted to a neutron leakage flux in the energy range 10 to 5 × 106ev by using the neutron detector calibration curve and Lingenfelter's calculated neutron energy spectrums at different latitudes. The neutron leakage flux is 0.08 ± 0.02 and 0.80 ± 0.10 neutrons/cm² sec at λ = 0° and λ = 70°, respectively. This latitude effect is about 10/1, less than the 13/1 ratio calculated by Lingenfelter in 1963. For λ<50°, the measured and the calculated

ISSN:0148-0227    

DOI:10.1029/JA073i021p06649

年代:1968

数据来源: WILEY

摘要:

The Pioneer 8 spacecraft was launched into an outbound heliocentric orbit on December 13, 1967. The payload includes a simple VLF electric field detector that uses the 423‐MHz antenna supplied for the Stanford radio propagation experiment. Broadband signals in the frequency range 0.1–100 kHz are examined by performing a pulse height analysis of the waveform, and wave amplitudes are also measured in bandpass channels centered at 0.4 and 22 kHz. It is found that low‐frequency electric field oscillations can always be detected in the solar wind, and that the amplitudes vary with changing interplanetary conditions. Large amplitude high‐frequency noise bursts are also detected sporadically, and we identify these as electron plasma oscillations in the sol

ISSN:0148-0227    

DOI:10.1029/JA073i021p06665

年代:1968

数据来源: WILEY

摘要:

The behavior of the magnetic field at the synchronous orbit during magnetospheric substorms is discussed for several events during December 1966 and January 1967. The vector measurements of the field were made with magnetometers on board the geostationary satellite ATS 1. The field was observed to be depressed and inclined radially outward in the dusk‐to‐midnight quadrant while substorms were in progress. Similar distortions of the magnetosphere were not observed in other local‐time sectors. When the satellite was near local midnight, the onset of the expansive phase of an auroral substorm was coincident with the recovery of the field at ATS 1. When the satellite was further toward the dusk meridian similar recoveries were observed, but they were followed by a renewed depression in the field. An interpretation of the data in terms of partial ring currents in the dusk‐to‐midnight quadrant is

ISSN:0148-0227    

DOI:10.1029/JA073i021p06687

年代:1968

数据来源: WILEY

摘要:

A sudden magnetic field increase associated with the July 8, 1966, sudden commencement (sc) was observed by the OGO 3 satellite in the magnetotail. By use of the IMP 3 and Explorer 33 observations made by Ness and Taylor of the interplanetary shock that caused the sc, it is shown that the magnetospheric propagation of the field increase toward the tail is faster than the propagation of the interplanetary shock just outside the bow shock. Conclusions drawn include (1) that the observed magnetic field increase in the tail is unlikely to be due to an increased lateral pressure of the postshock solar wind gas from the side of the tail, and (2) that the transfer of additional polar magnetic flux to the tail due to the increase in the solar wind pressure on the front side of the magnetosphere can account for the observed tail field increase.

ISSN:0148-0227    

DOI:10.1029/JA073i021p06699

年代:1968

数据来源: WILEY

摘要:

The particle energy density distribution for the symmetric portion of the April 17, 1965, magnetic storm has been deduced from the measured ring current magnetic field profile. This distribution contains a basic spatial distribution and a time decay term that is a function of distance in order to accomplish the fit between the calculated magnetic effects of the particles and the measured ring current field over a period of a day. With various assumptions as to the particle loss, the time decay yields the average energy of the particles as a function of distance and thence the total integral omnidirectional proton flux.

ISSN:0148-0227    

DOI:10.1029/JA073i021p06711

年代:1968

数据来源: WILEY

摘要:

Measurements of the interplanetary magnetic field in the vicinity of the moon have been made from lunar orbit on the Explorer 35 spacecraft. No shocks are observed in the vicinity of the moon, either in front of the moon or within 5.4RMbehind the moon. The interplanetary magnetic field appears to be convected past the lunar body without much distortion. A regular pattern of magnetic perturbations is observed when passing through the lunar wake. The perturbation amplitude is small and variable, typically less than 30% of the ambient interplanetary magnetic field. Simultaneous measurements made by Explorer 33 while in the interplanetary medium but not in the lunar wake show that even sharp changes in the interplanetary magnetic field are found essentially undistorted in the lunar wake. These simultaneous measurements also help to identify the magnetic perturbation pattern in the wake region.

ISSN:0148-0227    

DOI:10.1029/JA073i021p06723

年代:1968

数据来源: WILEY

摘要:

The structured elements in Pc 1 and Pi 1 events display dispersion characteristics of multihop and halfhop ULF whistlers, respectively. A large collection of these events has been analyzed for different magnetic field and plasma distribution models to obtain information about the source and propagation of these micropulsations as well as information about the magnetospheric plasma distribution. The Pc 1 propagation zone is centered about 75° geomagnetic latitude on the sunlit hemisphere and about 65° on the dark hemisphere. Although equatorial plasma densities are in general agreement with those determined from VLF whistler analysis, some differences exist that may be explained in terms of the generation mechanisms for the different waves. Evidence for steep gradients in the plasma density is presented. The region for propagation of structured Pi 1 elements is located between 6 and 13REat solar magnetospheric longitudes near 135°. The difference between the structured Pc 1 and Pi 1 elements is discussed in terms of hypothetical sources and the magnetospheric wave amplification by trapped particles in the ion‐cyclotron resonance interac

ISSN:0148-0227    

DOI:10.1029/JA073i021p06737

年代:1968

数据来源: WILEY

摘要:

Charge‐transfer cross sections resulting in either the production or the loss of H2O+were studied in the energy range 1 to 400 ev by using the crossed ion and neutral beam technique and employing mass analysis of the primary and product ions. The ions incident on H2O neutral beams were N+, O+, N2+, NO+, O2+and Ar+; the H2O+ion beams were incident on neutral beams of O2, NO, and H2O. The effects of the excited ions in the incident beam upon the cross sections were also investigated. The cross section for a rearrangement collision, H2O++ H2O → H3O++ OH, was also measured. The implications of these results to atmospheric models are discus

ISSN:0148-0227    

DOI:10.1029/JA073i021p06751

年代:1968

数据来源: WILEY

摘要:

By means of a 3‐m vacuum spectrometer, absorption coefficients of O2at the Lyman‐alpha line and its vicinity have been remeasured between 1214.8 and 1217.8 A. Coefficients at the wavelengths of the apparent doublet peaks of the Lyman‐alpha line, caused by self‐absorption and separated by 0.09 A, are pressure independent at relatively low pressure (p≤ 6.3 torr). The absorption coefficient at the shorter wavelength peak is 0.304 ± 0.002 cm−1, and that at the longer wavelength peak is 0.278 ± 0.002 cm−1. The minimum of the transmission window is located at about 1216.0 A, and its valu

ISSN:0148-0227    

DOI:10.1029/JA073i021p06759

年代:1968

数据来源: WILEY