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The significance of recent experimental observations on the annealing defects in n-type silicon has been examined. The observed anomalous annealing temperatures of A and E centers and their impurity concentration dependence are explained by an interference between the two centers.
The photodissociation of molecular species such as oxygen, nitrogen, and water vapor in the upper atmosphere leads to the formation of a reservoir of chemical energy consisting of highly reactive atomic gases. The reactions of these with each other, and with the rest of the atmosphere, give a complex neutral chemistry involving many species and reactions. Local equilibrium can rarely be assumed for these reactions; transport by the horizontal and vertical mean flow, by eddy diffusion, and by molecular diffusion has quite different effects on the various constituents, depending on the time constants. The entire subject of the neutral chemistry in the D and E regions (between 50 and 160 km altitude) is reviewed, and related to existing experimental results. Needs for further research on the subject are indicated.
A comparison of ion-molecule reaction rates implied by E- and F-region chemistry and measured in the laboratory shows on the whole good agreement except that the ionospheric analysis demands stronger temperature dependences. In the daytime D region, it is claimed that the reconciliation of positive ion densities with production rates and laboratory rate constants would best be achieved if (1) ionization of O2(1 delta g) and hydration of O4(+) in competition with the reduction of O4(+) to O2(+) by O were the dominant source of hydrates between 85 and 77 km, (2) ionization of NO by solar Lyman alpha followed by hydration was the dominant source of hydrates below 77 km, and (3) for some reason, Lyman alpha did not ionize NO effectively at pressures below those prevailing at 75 km.
Fluxgate magnetometer data obtained by OGO-5 near perigee were used to establish the existence of large field depressions in the magnetosphere under conditions of varying degree of disturbance at distances ranging from 2.3 to 3.6 R sub E at all local times. The results also provide the average delta B at these distances when Dst, as being derived at present, is zero.
Reduced and analyzed data from the plasma wave detector on OGO E spacecraft are reported. The bibliography lists 74 publications in scientific books and journals which highlight the analysis program.
Solar radiation in the extreme ultraviolet, lambda less than 1216 A, and X-ray regions of the spectrum is deposited between 60 and 200 km producing free electrons and ions. Below 60 km cosmic radiation creates ion pairs. Energetic electron precipitation, as during auroral events, creates additional ionization as do protons originating from solar flares, which also enhance solar X-ray and extreme ultraviolet emission. At night scattered solar Lyman alpha (1216 A) and Lyman beta (1026 A) as well as He I (584 A) and He II (304 A) are present. These and other lesser known sources, for example cosmic X-ray and extreme ultraviolet radiation, contribute to the formation of the nocturnal D and E regions.
Examination of the perturbed continuity equation when the perturbations are the result of an internal atmospheric gravity wave in the E region. The transient response of the ionization is interpreted as the gradient instability and the values of the vertical and horizontal wave numbers that will induce it are plotted for various heights. Only in the presence of westward directed electric fields, which are believed to occur only at night, will the gravity waves induce the gradient instability. Approximate analytic expressions are obtained for the permitted wave numbers as well as for the instability growth times. In the course of this analysis it is shown that in the D region all irregularities, even those that are field-aligned, will tend to move with the ion velocity.
At night, internal atmospheric gravity waves are able to induce drift instabilities in the ionospheric plasma. Nighttime constant height type sporadic-E(Esc) may then be explained as an effect due to the combined effect of ionization movement due to the wind shear mechanism and due to the cross-field gradient drifts. This combined concept provides a qualitative explanation of the rocket observed nighttime electron density profiles, of the speeds of the Esc irregularities and of the variations of Esc with latitude and electric field strength.-
This paper briefly describes the cylindrical electrostatic probes to be used on the new Atmosphere Explorer-C, -D, and -E, and outlines the methods to be employed to analyze the experimental data in terms of electron temperature and ion and electron concentration. Two independent cylindrical sensors and partially redundant electronic systems permit greater reliability in measurements. Measurements are made at 1-sec and 2-sec intervals along the orbit. The sensors themselves have been modified from previous applications to cope with the lower electron temperature expected in these low-altitude orbits and to counter possible surface contamination caused by the hydrazine engines used for orbit adjustments.
A search of the 3- to 30-keV data from the NRL proportional counter detector on the Orbiting Geophysical Observatory-5 (OGO-5) satellite has yielded several events which may be nearly completely nonthermal in the e greater than 3 and less than 10 keV range. In each case an impulsive hard X-ray burst accompained by an impulsive microwave burst was associated with a low energy X-ray burst whose profile was a simple rise and fall. The lack of a two component nature in the low energy range argues that the low energy X-ray flux is due to a single physical mechanism, in this case nonthermal bremsstrahlung from accelerated electrons. However, the spectra and time profiles are quite consistent with a thermal interpretation. Polarization measurements are probably necessary to resolve the physical origin of such bursts.
Auroral zone E region neutral winds have been derived from simultaneous measurements of ion drift velocities at different altitudes by the incoherent scatter radar facility at Chatanika, Alaska. The wind derived for quiet and moderately disturbed days shows a consistent pattern during the daytime and appears to be that expected from a day-night pressure asymmetry. In the nighttime, however, the winds are much more variable, apparently responding to the momentum transfer and heating effects of ion drag when sizable electric fields and electron densities are present.
Auroral zone E-region neutral winds have been derived from simultaneous measurements of ion drift velocities in different altitudes by the incoherent radar facility at Chatanika, Alaska, on a quiet day before and during the great magnetospheric storm of Aug. 3-9, 1972. The neutral wind expected for a day-night pressure asymmetry appears to be strongly opposed by ion drag and local pressure gradients in the auroral oval.
Background conditions for detecting (gamma e)-diffusion are discussed with reference to the utilization of a hodoscope system consisting of wide area flat Geiger counters connected for coincidence and of a controllable spark chamber. When calculating the background, any organic compounds synthesized from C, O2 and H2 with radioactive admixtures is presumed to be the preferrable material for the construction of the detector. The number of background events simulating the effect sought is estimated by analyzing the spectrum of the organic glass gamma radiation caused by disintegration and fission of long lived isotopes and by nuclear reactions with the participation of alpha particles and neutrons.
Electron temperatures and electron densities measured on four rocket flights have been used to deduce electron heating rates in the E and lower F regions. Above 150 km, heating rates at midday are found to be in good agreement with calculated values. Anomalies are found in the heating rates at sunrise which are attributed to a source, such as joule heating, which does not produce ionization.
A theory of electron-molecule scattering is developed which is a synthesis of close-coupling and adiabatic-nuclei theories. Specifically, the theory is close-coupling with respect to vibrational degrees of freedom and adiabatic-nuclei with respect to rotation. It can be applied to any number of partial waves required; the remaining ones can be calculated purely in one or the other approximation. A theoretical criterion based on fixed-nuclei calculations is given which indicates those partial waves and energy domains requiring the various approximations. The theory allows all cross sections (pure rotational, vibrational, simultaneous vibration-rotation, differential, and total) to be calculated, and explicit formulas for all these cross sections are given. The theory is applied to low-energy e-N2 scattering. The fixed-nuclei results are such that the criterion shows clearly that vibrational close coupling is necessary, but only for the Pi sub g partial wave. It is found that the close-coupling calculation for this wave gives rise to the substructure as well as the gross structure of the 2.4-eV resonance and that vibrational excitation cross sections are about twice as large as previously inferred.
By using rocket-borne Langmuir probes, electron temperature profiles have been obtained in five mid-latitude sporadic E layers. The data show the electron temperature within the layers to be lower than the electron temperature at the adjacent altitudes. This is consistent with the layers' being maintained by a vertical redistribution of ionization. The magnitude of the observed electron temperature variation is, however, larger than expected.
Observations of the electron density profile and flux of energetic electrons obtained in two rocket flights at Wallops Island near midnight are presented. The ionization rates of the upper E region deduced from the electron density profiles are found to support the dependence on Kp established in previous observation. Calculations of the ionization rates using the observed electron fluxes show agreement with the values derived from the electron density profiles.
Vibrational excitation cross sections of N2 by electron impact are tabulated. Integrated cross sections are given for transitions v yields v prime where o=or v=or 8 in the energy range 0.1 eV=or E=or 10 eV. The energy grid is chosen to be most dense in the resonance region (2 to 4 eV) so that the substructure is present in the numerical results. Coefficients in the angular distribution formula (differential scattering cross section) for transitions v=0 yields v prime = or 8 are also numerically given over the same grid of energies. Simultaneous rotation-vibration coefficients are also given for transitions v=o,j=o; 1 yields v prime=o, j=o,2,4; 1,3,5. All results are obtained from the hybrid theory.