摘要:

The differential spectrum of primary helium nuclei has been measured over the energy range 30 to 90 Mev per nucleon in six energy intervals. The results are well‐represented by the power spectrumdJ/dE= 1.15 × 10−5E1.4±0.2[m2sec ster Mev]−1whereJis the integral flux of He3and He4, andEis the total kinetic energy. This is the time‐averaged spectrum from November 27, 1963, to May 1, 1964, near the minimum of the solar activity cycle. There is evidence that this helium spectrum is the low‐energy extension of the modulated, interstellar spectrum of cosmic‐ray helium: (1) the helium nuclei were continuously present over the 5‐month period and not correlated with solar‐flare phenomena; (2) this helium spectrum extends smoothly into the higher‐energy spectrum for cosmic‐ray helium measured in balloons by others in 1963 and known to be of galactic origin; (3) during this period the helium flux increased approximately 35% while the higher‐energy cosmic radiation increased ∼6%; this is the expected qualitative behavior for the solar modulation of an interstellar spectrum of helium during the decay phase of the interplanetary magnetic fields. Since the Imp 1 (Explorer 18) satellite had an apogee of 198,000 km, primary helium measurements were obtained over most of the orbital period. The experimental apparatus consisted of a solid‐state, charged‐particle telescope which measured the energy loss and total energy of protons, helium, and some components of higher charge. The novel use of semi‐conductor detectors, and their dynamic range, energy resolution, stability, and linearity as a function of

ISSN:0148-0227    

DOI:10.1029/JZ070i015p03515

年代:1965

数据来源: WILEY

摘要:

The variations in the energy spectrums with pitch angle andLof the relatively stable 0.1‐to 5‐Mev protons in the outer radiation belt have been found to be in good agreement with the results of a model that permits rapid motion of the protons inLspace. In this model the third adiabatic invariant of the protons is violated, but not the first two adiabatic invariants. The variations in flux with L are found to indicate an external source and are discussed qualitativ

ISSN:0148-0227    

DOI:10.1029/JZ070i015p03529

年代:1965

数据来源: WILEY

摘要:

Observations of the temporal variations of electron (E>1.6 Mev) intensities near the geomagnetic equator in the outer radiation zone with Explorer 14 (October 2, 1962, to August 8, 1963) strongly suggest that replenishment of energetic electrons in the outer radiation zone during the several weeks following a period of geomagnetic activity proceeds by an inward radial motion of energetic electrons fromL>5. The apparent, inward radial velocity of the ‘wave’ of electrons (E>1.6 Mev) is ∼0.4 earth radius (day)−1atL= 4.7 and ∼0.03 earth radius (day)−1atL=3.4, and varies as ∼L8between theseLshells. These inward radial velocities for the several replenishment cycles of outer‐zone electrons (E>1.6 Mev) observed with Explorer 14 at a givenLshell are equal to within experimental errors. These measurements provide evidence for a continually active mechanism for diffusing energetic electrons acrossLshells in the outer

ISSN:0148-0227    

DOI:10.1029/JZ070i015p03533

年代:1965

数据来源: WILEY

摘要:

The magnetic effects of the quiet‐time proton belt have been studied by means of data obtained from a proton detector aboard Explorer 12. From the measured energy spectrums, intensities, and pitch‐angle distributions of the protons with energies above 100 kev, the current density on a magnetic meridian plane was calculated using the theory of Akasofu and Chapman, modified to eliminate several simplifying assumptions. The algebraic sum of all the currents was 0.59 million amperes, and the magnetic moment of the current loop was 0.029ME. The magnetic perturbations on the meridian plane were obtained from the electric current distribution. At the magnetic equator on the earth's surface the proton belt produced a 9 γ decrease in the field, which is considerably less than the 38 γ decrease reported by Akasofu, Cain, and Chapman. Their calculations were based on very preliminary data from the same detector which yielded a total kinetic energy of the trapped protons of 2.38×1022ergs, whereas the analysis performed here yields an energy of only 5.7×1021ergs. The maximum perturbation appeared atL=3.6 on the magnetic equator, where the field attained a value o

ISSN:0148-0227    

DOI:10.1029/JZ070i015p03541

年代:1965

数据来源: WILEY

摘要:

A set of scintillation counters was carried on polar‐orbiting Air Force satellites in the last half of 1961. Cosmic‐ray effects were observed at high latitudes with good statistics. TheLvalue of the ‘edge’ of the cosmic‐ray plateau was found to vary with longitude and to vary betweenL= 2.7 andL= 3.3. This corresponds to a ‘knee’ at fromL= 3.1 toL= 3.7. A‘kneecap,’ consistently observed at the plateau edge, is interpreted as the appearance of reentrant albedo as the satellite moves to lower latitudes. The relative amount of this albedo was 8±2% at an altitude of 300 km. A day‐night effect in the observed high‐latitude reentrant albedo cutoff is consistent with known day‐night changes in the magnetosphere. The observed altitude dependence of flux at very high latitudes is used to derive an omnidirectional interplanetary flux of 2.6±0.3 part

ISSN:0148-0227    

DOI:10.1029/JZ070i015p03557

年代:1965

数据来源: WILEY

摘要:

An anomalous increase in the flux of low‐energy neutrons (0.02 ev to ∼5 Mev) was detected at aircraft altitudes on January 21, 1964, between 0350 and 0400 UT. The aircraft (at an altitude of 39,000 feet and a geographic position between 38° and 35°S latitude in the region of the magnetic anomaly east of Buenos Aires) was instrumented with ionospheric sounding gear, three cosmic‐ray neutron counters, and night airglow monitors. The increase in the neutron flux, which was detected by all three neutron counters, coincided with an increase in the intensity of the night airglow monitored in the same a

ISSN:0148-0227    

DOI:10.1029/JZ070i015p03571

年代:1965

数据来源: WILEY

摘要:

The October 7, 1962, event, as seen by the plasma probe aboard Explorer 14, was characterized by the appearance of plasma approximately 2 minutes after the ground‐level sudden impulse. The spacecraft at this time was outbound at 13.5 earth radii. Before this event no plasma was observed. The results presented are consistent with a compression of the magnetospheric boundary below the altitude of the spacecraft. Data are further presented to give evidence for momentary penetration by Explorer 14 of the postulated bow shock. Comparisons are made with Mariner 2 magnetometer and plasma probe data with consideration given to the time delay associated with the propagation of the disturbance from Mariner 2 to eart

ISSN:0148-0227    

DOI:10.1029/JZ070i015p03575

年代:1965

数据来源: WILEY

摘要:

A number of experiments are described whose purpose was to determine whether peaks in power spectrums of time series of solar indices reflect a tendency for equidistant separation in longitude of solar active regions or are produced by the analysis technique. From comparisons of power spectrums of artificial time series with the spectrum of a solar plage index it is clear that there is no appreciable tendency for equidistant spacing of active regions.

ISSN:0148-0227    

DOI:10.1029/JZ070i015p03581

年代:1965

数据来源: WILEY

摘要:

The magnetic disturbances produced on a worldwide scale by high‐altitude nuclear detonations are treated. The characteristics of the magnetic signals from Argus 3 and Starfish are briefly discussed. Particularly, the fast propagation time observed for the early part of the signal is explained by the magnetohydrodynamic‐electromagnetic coupling mechanism. An idealized model is explored of excitation of extremely low frequency electromagnetic waves in a cylindrical vacuum cavity by magnetohydrodynamic waves incident from the surrounding plasma. It is found that there is a characteristic time needed for the cavity waves to respond to this external excitation: no matter how fast the excitation, the cavity wave amplitude changes in a time of the order of 2 seco

ISSN:0148-0227    

DOI:10.1029/JZ070i015p03587

年代:1965

数据来源: WILEY

摘要:

The dynamic spectrums of micropulsation pearls (type Pc 1) recorded at stations in various latitudes were studied to obtain the frequencies and the spacing times of the fine structure elements comprising pearl events. In confirmation of earlier results, the product of these two parameters is found to be nearly independent of latitude. However, the parameters are themselves functions of latitude, both the spacing time and the reciprocal of the frequency being almost proportional to theLvalue. These dependences are such as to account for the tendency of the frequency‐spacing time product to be constant. An attempt to discriminate between Alfvén wave and particle bunch hypotheses for the generation of pearls was made by comparing the experimental results with computations of the travel time over the field line as a function of latitude. It appears that mirroring particle bunches with a velocity of about 1270 km/sec could account for the observed latitude effe

ISSN:0148-0227    

DOI:10.1029/JZ070i015p03595

年代:1965

数据来源: WILEY