摘要:

From an analysis of the data from the worldwide network of neutron monitor stations, the general characteristics of the yearly mean semi‐diurnal component of cosmic radiation are derived. The mean semi‐diurnal component in the energy range 1–200 Gev can be represented as [ΔJ(R)/J(R)] = 4 × 10−5Rcos² Λ, forR200 Gv. The semi‐diurnal component has a maximum along a direction perpendicular to the direction of the mean interplanetary field vector, varies as the first power of rigidity, and varies as cos² Λ where Λ is declination. The phase and the amplitudes of the semi‐diurnal component also seem to be practically invariant with time during the period 1958‐1968. The mean properties of the semi‐diurnal anisotropy are consistent with the hypothesis of a positive density gradient of cosmic ray intensity in a direction perpendicular t

ISSN:0148-0227    

DOI:10.1029/JA075i013p02391

年代:1970

数据来源: WILEY

摘要:

A 2‐fluid model for the solar wind is discussed, in which the electrons, at constant temperature, are treated hydrodynamically and the protons are assumed to become collisionless, at a distance from the sun at which they are already supersonic. A radial magnetic field is included, with radial gravitational and electric fields; the electric field arises from the condition of quasi‐neutrality and is an important feature of the model. Quantities such as bulk velocity, concentration, and proton temperatures parallel and perpendicular to the magnetic field are discussed directly in terms of the proton distribution function; viscosity and heat conduction are thus automatically included. The principle result is that if the electron temperature in the vicinity of the point where the electrons become collisionless (10–20 solar radii from the sun) is of the order 106°K, the flow velocity at the orbit of the earth is in excess of 300 km/sec, and the average proton temperature is of the order of 10,000 °K. Both of these figures are higher than those obtained by the 2‐fluid hydrodynamical model. The velocity far from the base of the model varies asTe1/2and is relatively insensitive to temperature or velocity at the base or to the location of the base. The thermal anisotropy of the protons,T∥/T⊥, is predicted t

ISSN:0148-0227    

DOI:10.1029/JA075i013p02403

年代:1970

数据来源: WILEY

摘要:

A steady state axially symmetrical model for the flow of the solar wind near the equatorial plane is developed. The radial motion is regarded as known, and the azimuthal motion is investigated, allowing for magnetic forces, viscosity (as modified by the magnetic field), and anisotropic pressure. We show that to obtain a smooth continuous solution the constant of integration has to be determined, not from a boundary condition at the sun, but by the behavior of the solution near the critical radiusrA, where the radial Mach number is unity. The viscosity considerably increases the tendency toward corotation in the region between five solar radii and 1 AU. The azimuthal velocity predicted near the earth is of the order of 6 km/sec for what may be regarded as typical conditions (temperature of 2× 05°K and a radial wind velocity of 400 km/sec), whereas the velocity is 1 km/sec for a nonviscous isotropic mode

ISSN:0148-0227    

DOI:10.1029/JA075i013p02419

年代:1970

数据来源: WILEY

摘要:

Measurements of the magnetosheath plasma made by the MIT plasma experiment during the outbound passage of Pioneer 6 in the dusk meridian (December 16, 1965) are presented and compared with theoretical predictions and other simultaneous experimental measurements for the same region. Though comparison with theory indicates that the plasma flow around the earth agrees in many ways with a gasdynamic model, observed discrepancies in the density ratio across the bow shock and the non‐Maxwellian velocity distribution in the magnetosheath warrant further explanation. Proton observations in the magnetosheath next to the bow shock indicate that the non‐Maxwellian high‐energy tail of the proton velocity distribution may be due in part to an effect that is independent of the main flow. Magnetosphere and magnetosheath low‐energy electron measurements indicate a region of anisotropic flux in the magnetosphere near the magne

ISSN:0148-0227    

DOI:10.1029/JA075i013p02429

年代:1970

数据来源: WILEY

摘要:

The existence of an equilibrium layer between a magnetic field and a field‐free stream of cold plasma, moving perpendicularly to the field, was shown many years ago by Ferraro. Recently, Parker treated the interaction of a plasma stream and a magnetic field under somewhat different assumptions. It was assumed that the plasma stream has a velocity component parallel to the confining magnetic field, and that no potential difference can exist within the layer. From these assumptions, the conclusion was drawn that no equilibrium exists. In the present paper we show that a layer without any potential difference cannot be part of a self‐consistent model. It is shown that at the outer border of the layer there must be a potential barrier, retarding the ions and accelerating the electrons in such a way that there is an overall charge neutrality of thestreamparticles within the layer. The charge neutrality of the layer will automatically ensure the equilibrium of a layer between a cold plasma stream and a magnetic fi

ISSN:0148-0227    

DOI:10.1029/JA075i013p02438

年代:1970

数据来源: WILEY

摘要:

The analysis is based on 5.46‐min magnetic field averages measured by the IMP 3 satellite. The effect of the inclination χ of the earth's magnetic axis with respect to theY,Z‐plane of solar magnetospheric coordinates (perpendicular to the earth‐sun line) is studied in detail, and a thick sheet of magnetic field depression is shown to exist around the neutral sheet at distances of 30 to 38REin the antisolar direction. The location of the region of magnetic field depression varies with the value of χ; the thickness of the depression region is about 10REin the central parts of the tail,Y≈0, and is probably higher forY>10RE. The region of magnetic field depression is identified with the plasma sheet. The sheet of magnetic field depression is characterized by very large, long time‐scale fluctuations parallel to the average local magnetic field. A ‘flapping motion’ of the neutral sheet may be responsible for the large values of some of these fluctuations. The fluctuations perpendicular to local magnetic field are nearly independent of position in the magnetotail. Both types of fluctuations are enhanced during and/or after sudden storm commencements (ssc) and sudden impulses (si) observed at ground stations. The effect is more clearly seen in the perpendicular fluctuations. The information from the interaction between the magnetosphere and a discontinuity in the interplanetary medium is transferred mainly along the

ISSN:0148-0227    

DOI:10.1029/JA075i013p02449

年代:1970

数据来源: WILEY

摘要:

By using a simple model with constant convection electric field and a dipole magnetic field, plasma flow patterns are calculated with the convection fields as scale factors. Unlike other particle trajectories, the flow patterns for protons with certain relative magnetic moments show double forbidden regions: one is composed of orbits that circle the earth; the other is composed of orbits that do not circle the earth. These protons can penetrate very close to the earth through the space between the two forbidden regions. The calculations based on the model of constant electric field with charge exchange as a loss mechanism indicate that protons of a few hundred electron volts convected in from the tail toL= 3–4 could be responsible for the storm‐time ring curre

ISSN:0148-0227    

DOI:10.1029/JA075i013p02458

年代:1970

数据来源: WILEY

摘要:

Observations of the energy fluxes of ≳5‐kev electrons at low altitudes (∼525–2500 km) over the northern auroral regions have been made by the nearly polar orbiting Injun 4 satellite, from February 1965 through July 1966, during a period of minimum solar activity. Results of the first detailed survey of the percentages of occurrence of the energy fluxes of ≳5‐kev electrons (with pitch angles ∼40°±15°) in the outer radiation/auroral zone, as a function of magnetic local time and invariant latitude, are graphically displayed for various energy flux thresholds. The greatest occurrences of these energy fluxes were observed in the night‐dawn‐morning hours of local time, at latitudes from ∼65° to ∼70°, with median energy fluxes as great as 0.1 ergs(cm² sec sr)−1. The spatial distributions of these contours are compared with those for the occurrences of optical auroras. Limited simultaneous observations of these energy fluxes at pitch angles of ∼40° and ∼90° have shown that the ratios of these energy fluxes are typically greater than 0.1, with a condition of isotropy occurring for

ISSN:0148-0227    

DOI:10.1029/JA075i013p02468

年代:1970

数据来源: WILEY

摘要:

Direct measurements of the distributions of the thermal positive ions H+and He+in the magnetosphere reveal a distinct variability in the position and structure of the plasmapause. Such variability is observed to be most pronounced in the afternoon‐dusk local time sector and is indicative of magnetospheric irregularities in the same region. As the OGO 3 satellite made progressive duskside (1500–1900 LT) and nightside (2200–0100 LT) passes during June–July 1966, the duskside plasmasphere was observed to exhibit an outward expansion or bulge, accompanied in some cases by considerable fine structure. In particular, the plasmapause was observed atLpositions as distant asL= 7–8 in the afternoon‐dusk sector, in contrast to positions nearL= 5–6 observed near midnight on the same day and at comparable levels of moderate magnetic activity (Kp≤3). Within the bulge and just above the initial plasmapause, structured plasma recoveries are observed, whereinn(H+) returns to concentrations of the order of 50–100 ions/cm³ over intervals of 0.5–1.5L. Both the duskside bulge and fine structure are observed to persist during periods of enhanced magnetic activity (Kp= 4–6). The above variability is superimposed on an average diurnal distribution of the plasmapause that is similar in shape to that deduced from whistler data during 1963, although the 1966–1967 results place the plasmapause at a position generally more

ISSN:0148-0227    

DOI:10.1029/JA075i013p02481

年代:1970

数据来源: WILEY

摘要:

Data from a VLF electric field antenna on board the spacecraft OV3‐3 show that the antenna response depends upon the local plasma density. Antenna impedances, calculated on the basis of a cold, magnetized plasma model and a warm, nonmagnetized, collisionless plasma sheath model, are compared with the data, showing that the sheath model is more appropriate. The response of the electric field antenna to constant onboard sources of electromagnetic interference is used with the antenna sheath impedance model to calculate plasma densities. The resulting densities are similar to those obtained from OGO 2 plasma density data scaled to the OV3‐3 orbital parameters. The impedance of the TRW Systems Group VLF electric field antenna, also on board OV3‐3, is calculated and compared with the data. It is shown that the sheath antenna impedance model applies equally well to both antennas even though they were quite dissimilar. Much of the signal variation observed by the Aerospace and TRW electric field antennas is caused by antenna impedance changes as a function of local plasma de

ISSN:0148-0227    

DOI:10.1029/JA075i013p02490

年代:1970

数据来源: WILEY