摘要:

Several people have computed numerically the magnetic field caused by an axially symmetric body of plasma imbedded in a dipole magnetic field. In the present paper we derive an approximate formula for this magnetic field, without first choosing a particular functional form for the plasma density. This has the consequence that we can easily discuss any particular case without recourse to a computer, whereas previous treatments resulted in a tabulation of an answer for a particular case only, and new cases required new computer runs. The method used avoids the usual fine net required by the singularity in the integrand. We achieve this by constructing a new quadrature formula which treats this singularity exactly. The then permitted coarse net makes possible an algebraic treatment rather than a numerical one.

ISSN:0148-0227    

DOI:10.1029/JZ069i021p04421

年代:1964

数据来源: WILEY

摘要:

Sea level neutron monitor latitude surveys carried out at the times of solar minimum and solar maximum are compared. The data, suitably normalized with reference to a high latitude neutron monitor, are used to arrive at the fractional decrease in primary flux between these periods as a function of magnetic rigidity up to 15 Gv.

ISSN:0148-0227    

DOI:10.1029/JZ069i021p04429

年代:1964

数据来源: WILEY

摘要:

The abundance of low energy deuterons and tritons has been determined in a nuclear emulsion stack exposed at Fort Churchill, Manitoba, Canada (geomagnetic latitude λ = 73°N), on August 4, 1962, under 4.2 g/cm2of residual atmosphere. Using the grain density versus residual range method for the identification of tracks produced by particles, the differential flux of deuterons and tritons has been determined. The results appear to be consistent with the absence of deuterons and tritons in the primary cosmic radiation. An upper limit has been placed on the amount of hydrogen traversed by low energy cosmic ray particle

ISSN:0148-0227    

DOI:10.1029/JZ069i021p04435

年代:1964

数据来源: WILEY

摘要:

A scale model laboratory experiment simulating the effect of the solar wind on the magnetosphere has been performed. On the basis of photographic and magnetic field measurements, two distinct types of interactions, depending on the properties of the solar wind, can be distinguished. The ‘standoff’ interaction shows a complete standoff of the impinging solar wind plasma at several earth radii away from the terrella. No visible injection of the ‘wind’ into the region of the terrella is observed. A very steep gradient of the magnetic field at the position of the standoff and the formation of discrete inner regions of plasma are found. The ‘injection’ interaction is characterized by the injection at high latitudes of plasma into the vicinity of the terrella merging into a single wake or tail. The visible plasma regions to windward generally exhibit considerable radial thickness and diffuse edges. Magnetic measurements show a much more gradual compression of the magnetic field and no discrete in

ISSN:0148-0227    

DOI:10.1029/JZ069i021p04441

年代:1964

数据来源: WILEY

摘要:

A computer study has been made of the efficiency of the IGY cosmic radiation neutron monitor and of the improved NM‐64 monitor intended for the IQSY. A reactor shielding program was used to calculate the probabilities of detecting evaporation and cascade neutrons of different energies which originated in the monitor. The probability of detecting nuclear disintegrations within the monitor has then been estimated using neutron multiplicities predicted by evaporation theory. The over‐all sensitivity and energy dependence are compared for the two monit

ISSN:0148-0227    

DOI:10.1029/JZ069i021p04451

年代:1964

数据来源: WILEY

摘要:

During three separate balloon flights made in the auroral zone, it was found that the precipitation of energetic electrons occurred by means of short, impulsive bursts having definite features. Since these bursts were found to have no substructure, they have been called microbursts. They are homogeneous with respect to rise time and duration; the decay time is less consistent. Periodic studies of microburst spacings have revealed no strong period, but a departure from purely random behavior can be shown. Some of the characteristic times of microbursts can be explained on the basis of electron motions on the auroral zone line of force.

ISSN:0148-0227    

DOI:10.1029/JZ069i021p04457

年代:1964

数据来源: WILEY

摘要:

A study has been made of eight separate solar cosmic ray events that occurred during 1960 using (a) observations above the atmosphere by satellite Explorer 7 of the integral omnidirectional intensity of particlesJ0(E>E0), whereE0is 30 Mev for protons and 120 Mev for α particles; and (b) corresponding riometer values of atmospheric absorptionAof cosmic radio noise at 27.6 Mc/s from College and Thule stations. The quantitiesA/J01/2andJ0/A2are calculated as functions of kinetic energyEfor monoenergetic beams of pure protons and pure α particles. Using these results, we show that certain specified ranges of the experimental parameterH(E0) = J0(E>E0)/A2for actual solar cosmic ray beams lead uniquely to one of the following conclusions: The atmospheric absorption is due primarily to particles of energy (a) less thanE0, (b)approximately equal toE0, or (c) greater thanE0. Observed values ofHare quite different for different events during 1960, covering the range 40 to less than 10−2(db2cm2sec)−1. During a given event the prevailing tendency is forHto remain approximately constant or to decrease (sometimes markedly) butnotto increase with increasing time. It is concluded that atmospheric absorption over the polar caps is often due predominantly to protons of energy less than 30 Mev and/or to α particles of energy less than 120 Mev and that the spectral form in the vicinity of these values of energy varies greatly from event to event and tends to remain about the same or to become steeper (softer) with increasing time during a given

ISSN:0148-0227    

DOI:10.1029/JZ069i021p04481

年代:1964

数据来源: WILEY

摘要:

A simultaneous study of radio wave absorption and luminous aurora at College, Alaska, using narrow beam antennas, 5577 A photometers, and all‐sky cameras resulted in the conclusion that the nighttime radio wave absorption observed at College falls into the following two main categories. The absorption belonging to category 1 is observed at any time between 2000 and 0200h, correlates well with the intensity fluctuations of 5577 A, and is limited to luminous regions of the sky. Included in this category is the absorption associated with the quiet as well as bright and active phases of the display. The absorption belonging to category 2 is observed only in the postmidnight hours, does not correlate with the intensity fluctuations of 5577 A and, most probably, is not limited to luminous regions of the sky. With the absorption making a transition from category 1 to category 2, a 10‐ to 100‐fold increase takes place in the ratio of absorption to 5577 A intensity. The close association between radio wave absorption and luminous aurora during absorption events of category 1 suggests that the primary particles are approximately in the energy range 10–20 kev. It is shown that the absorption associated with the quiet phase of the display is easily explained by a flux of 107–108electrons cm−2sec−1in the range 10–20 kev. It is also shown that the transition from the quiet phase to the bright and active phase can be explained by a momentary 10‐ to 100‐fold increase in the flux of low energy electrons. The lack of correlation between absorption and 5577 A intensity fluctuations and the pronounced increase in the ratio of absorption to 5577 A intensity observed during absorption events of category 2 are indicative of a hardening of primary particle energy spectrum, possibly because of injection of a large number of electrons in the energy range 30–100 kev. It is estimated that a flux of 106–107electrons cm−2sec−1in the above energy range can adequately account for the observed absorption

ISSN:0148-0227    

DOI:10.1029/JZ069i021p04493

年代:1964

数据来源: WILEY

摘要:

The transfer of energy between whistler‐mode signals and energetic charged particles is examined. Resonance conditions are derived, leading to a classification of the mechanisms previously suggested for the generation of VLF emissions. The relationship between change in energy and change in pitch angle of the particles is derived for the transverse resonance interaction with longitudinal whistler‐mode waves. Features of the transverse resonance plasma instabilities and the anomalous Doppler effect are clarif

ISSN:0148-0227    

DOI:10.1029/JZ069i021p04515

年代:1964

数据来源: WILEY

摘要:

Measurements of the amplitude and phase of VLF radio waves over long paths are discussed. A system that permits the simultaneous measurement of phase and amplitude of VLF signals over complementary great circle paths is described. Phase and amplitude measurements of NAA VLF transmissions (18.6 kc/s) obtained simultaneously at San Diego over the two great circle paths are shown. A simple preliminary analysis of the data is used to show that the difference in the magnitudes of the amplitude over the two paths is in good agreement with that predicted by previously published attenuation rates. A change in long path amplitude during sunset at the transmitter is attributed to an excitation factor change, and it appears to be in good agreement with theory.

ISSN:0148-0227    

DOI:10.1029/JZ069i021p04523

年代:1964

数据来源: WILEY